W&T Wetenschap & Technologie
Een plek om te discussiëren over wetenschappelijke onderwerpen, wetenschappelijke problemen, technologische projecten en grootse uitvindingen.
01-06-2015
Verloren herinneringen kunnen terug opgehaald worden via
© thinkstock.
Herinneringen die 'kwijt' lijken te zijn, zitten toch nog ergens in de hersenen opgeslagen. Via een techniek met licht kunnen ze bovendien terug opgehaald worden, dat ontdekten wetenschappers bij een experiment met muizen. De bevinding is vooral interessant voor de behandeling van patiënten met amnesie of geheugenverlies.
In een experiment met muizen dat gepubliceerd werd in het tijdschrift 'Science' deden enkele onderzoekers een opmerkelijke bevinding. Ze slaagden er namelijk in om herinneringen terug te activeren, die voordien niet meer herinnerd konden worden door de onderzochte muizen. Het enige wat ze daarvoor nodig hadden, was licht. De onderzoekers gebruikten een speciale techniek die zenuwen in de hersenen kan stimuleren door lichtflitsen.
En zo blijkt er dus toch hoop te zijn voor mensen die lijden aan amnesie. Hun onvermogen om herinneringen op te halen, blijkt volgens het experiment een heel andere oorzaak te hebben dan gedacht. Dat kan het onderzoek naar de ziekte en ook de behandeling van de patiënten meer doeltreffend maken.
Geheugenverlies
Amnesie of geheugenverlies kan optreden na een ernstig ongeval of kan veroorzaakt worden door een ziekte, zoals Alzheimer. De overgrote meerderheid van wetenschappers meenden dat in dergelijke gevallen de cellen in de hersenen waren aangetast, waardoor een herinnering niet meer correct opgeslagen kon worden en bijgevolg ook niet meer kon opgehaald worden. Dat lijkt nu dus tegengesproken te worden in huidig onderzoek.
"We hebben kunnen aantonen in ons experiment dat de theorie rond amnesie, die wereldwijd als de meest aannemelijke werd beschouwd, waarschijnlijk niet klopt. We konden namelijk vaststellen dat de muizen herinneringen konden terughalen, die eerder verloren leken te zijn. Dat betekent dat amnesiepatiënten nog wel degelijk herinneringen correct kunnen opslaan en dat het echte probleem dus ligt bij het ophalen ervan", verklaart Susumu Tonegawa, professor aan de faculteit Technologie in Cambridge.
(HLN)
Verloren herinneringen kunnen terug opgehaald worden via
© thinkstock.
Herinneringen die 'kwijt' lijken te zijn, zitten toch nog ergens in de hersenen opgeslagen. Via een techniek met licht kunnen ze bovendien terug opgehaald worden, dat ontdekten wetenschappers bij een experiment met muizen. De bevinding is vooral interessant voor de behandeling van patiënten met amnesie of geheugenverlies.
In een experiment met muizen dat gepubliceerd werd in het tijdschrift 'Science' deden enkele onderzoekers een opmerkelijke bevinding. Ze slaagden er namelijk in om herinneringen terug te activeren, die voordien niet meer herinnerd konden worden door de onderzochte muizen. Het enige wat ze daarvoor nodig hadden, was licht. De onderzoekers gebruikten een speciale techniek die zenuwen in de hersenen kan stimuleren door lichtflitsen.
En zo blijkt er dus toch hoop te zijn voor mensen die lijden aan amnesie. Hun onvermogen om herinneringen op te halen, blijkt volgens het experiment een heel andere oorzaak te hebben dan gedacht. Dat kan het onderzoek naar de ziekte en ook de behandeling van de patiënten meer doeltreffend maken.
Geheugenverlies
Amnesie of geheugenverlies kan optreden na een ernstig ongeval of kan veroorzaakt worden door een ziekte, zoals Alzheimer. De overgrote meerderheid van wetenschappers meenden dat in dergelijke gevallen de cellen in de hersenen waren aangetast, waardoor een herinnering niet meer correct opgeslagen kon worden en bijgevolg ook niet meer kon opgehaald worden. Dat lijkt nu dus tegengesproken te worden in huidig onderzoek.
"We hebben kunnen aantonen in ons experiment dat de theorie rond amnesie, die wereldwijd als de meest aannemelijke werd beschouwd, waarschijnlijk niet klopt. We konden namelijk vaststellen dat de muizen herinneringen konden terughalen, die eerder verloren leken te zijn. Dat betekent dat amnesiepatiënten nog wel degelijk herinneringen correct kunnen opslaan en dat het echte probleem dus ligt bij het ophalen ervan", verklaart Susumu Tonegawa, professor aan de faculteit Technologie in Cambridge.
(HLN)
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
HERE'S WHAT HAPPENS TO YOUR BRAIN ON THE WAY TO MARS
Early studies suggest it's probably nothing good.
AMY THOMPSON 6 JUN 2015
NASA plans to send a crewed mission to Mars within the next 20 years, but a recent study indicates that the trip might be more hazardous than previously thought. New data has shown that exposure to cosmic rays could severely impair an astronaut’s cognitive functions over the course of a long-duration, deep space mission.
In a laboratory setting, researchers from the University of California, Irvine in the US simulated the harsh conditions of deep space by subjecting a group of mice to blasts of accelerated particles, similar to cosmic rays. The results indicated that the irradiated mice had slower response times, were forgetful, and even confused.
"This is not positive news for astronauts deployed on a two- to three-year round trip to Mars," one of the team Charles Limoli, a professor of radiation oncology, said in a press release. "Performance decrements, memory deficits, and loss of awareness and focus during spaceflight may affect mission-critical activities, and exposure to these particles may have long-term adverse consequences to cognition throughout life."
Cosmic rays - the by-product of galactic explosions such as supernovae - are high-energy charged particles speeding through space. They can penetrate the hull of a spacecraft and human bones with ease, causing significant damage to the body’s central nervous system.
On Earth, the magnetosphere acts as a protective bubble, shielding us from the damaging effects of these rays, but the tenuous Martian atmosphere offers no such protection. Our magnetosphere extends 56,000 kilometres (35,000 miles) above Earth’s surface, and as such, even the astronauts on board the International Space Station are protected against these harmful rays.
In the study, published in Science Advances and conducted at NASA’s Space Radiation Laboratory at the Brookhaven National Laboratory in New York, a group of genetically altered mice were blasted with beams of oxygen and titanium ions accelerated to two-thirds the speed of light - the same type of ions found in galactic cosmic rays. The mice were genetically altered to have glowing fluorescent neurons, making it easier for scientists to study changes in their brains.
Six weeks after exposure, the irradiated mice had 30 to 40 percent fewer dendrites - the branches between neurons that carry electrical signals - than the control group. Exposure to the blasts of cosmic rays triggered the degradation of the dendrites and persisted over time. This loss of dendrites is associated with the mental decline seen patients who suffer from Alzheimer’s and similar neurological diseases.
Both groups of mice were then put through a battery of cognitive tests designed to test their learning and memory functions. New objects were placed among familiar objects and the team watched as the irradiated mice became confused more easily and lacked curiosity when compared with the control group. If the same changes were to occur in astronauts while in space, their ability to react quickly or to recall information would be affected.
With Mars missions expected to last between two and three years, any effect from cosmic ray exposure would have ample time to manifest. Astronauts’ ability to carry out mission duties, such as multitasking and conducting research experiments, as well as their overall cognitive health, could be compromised. Limoli and his team do not think the level of impairment would be so severe that an astronaut would wreck a spaceship; however, they could easily ruin an experiment.
The brain is a complex system and longer-term studies are required before we understand the full effects of cosmic rays, and can determine if the structural and behavioral changes seen in the mice are permanent.
http://www.sciencealert.c(...)n-on-the-way-to-mars
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
NEW STUDY CLAIMS TO FIND GENETIC LINK BETWEEN CREATIVITY AND MENTAL ILLNESS
Results imply creative people are 25% more likely to carry genes that raise risk of bipolar disorder and schizophrenia. But others argue the evidence is flimsy
A detail from Vincent van Gogh’s Self-portrait with Bandaged Ear, 1889. The artist himself expressed dismay at the impact his mental illness had on his work. Photograph: Peter Barritt/Getty Images/SuperStock RM
The ancient Greeks were first to make the point. Shakespeare raised the prospect too. But Lord Byron was, perhaps, the most direct of them all: “We of the craft are all crazy,” he told the Countess of Blessington, casting a wary eye over his fellow poets.
The notion of the tortured artist is a stubborn meme. Creativity, it states, is fuelled by the demons that artists wrestle in their darkest hours. The idea is fanciful to many scientists. But a new study claims the link may be well-founded after all, and written into the twisted molecules of our DNA.
In a large study published on Monday, scientists in Iceland report that genetic factors that raise the risk of bipolar disorder and schizophrenia are found more often in people in creative professions. Painters, musicians, writers and dancers were, on average, 25% more likely to carry the gene variants than professions the scientists judged to be less creative, among which were farmers, manual labourers and salespeople.
Kari Stefansson, founder and CEO of deCODE, a genetics company based in Reykjavik, said the findings, described in the journal Nature Neuroscience, point to a common biology for some mental disorders and creativity. “To be creative, you have to think differently,” he told the Guardian. “And when we are different, we have a tendency to be labelled strange, crazy and even insane.”
The scientists drew on genetic and medical information from 86,000 Icelanders to find genetic variants that doubled the average risk of schizophrenia, and raised the risk of bipolar disorder by more than a third. When they looked at how common these variants were in members of national arts societies, they found a 17% increase compared with non-members.
The researchers went on to check their findings in large medical databases held in the Netherlands and Sweden. Among these 35,000 people, those deemed to be creative (by profession or through answers to a questionnaire) were nearly 25% more likely to carry the mental disorder variants.
Stefansson believes that scores of genes increase the risk of schizophrenia and bipolar disorder. These may alter the ways in which many people think, but in most people do nothing very harmful. But for 1% of the population, genetic factors, life experiences and other influences can culminate in problems, and a diagnosis of mental illness.
“Often, when people are creating something new, they end up straddling between sanity and insanity,” said Stefansson. “I think these results support the old concept of the mad genius. Creativity is a quality that has given us Mozart, Bach, Van Gogh. It’s a quality that is very important for our society. But it comes at a risk to the individual, and 1% of the population pays the price for it.”
Stefansson concedes that his study found only a weak link between the genetic variants for mental illness and creativity. And it is this that other scientists pick up on. The genetic factors that raise the risk of mental problems explained only about 0.25% of the variation in peoples’ artistic ability, the study found. David Cutler, a geneticist at Emory University in Atlanta, puts that number in perspective: “If the distance between me, the least artistic person you are going to meet, and an actual artist is one mile, these variants appear to collectively explain 13 feet of the distance,” he said.
Most of the artist’s creative flair, then, is down to different genetic factors, or to other influences altogether, such as life experiences, that set them on their creative journey.
For Stefansson, even a small overlap between the biology of mental illness and creativity is fascinating. “It means that a lot of the good things we get in life, through creativity, come at a price. It tells me that when it comes to our biology, we have to understand that everything is in some way good and in some way bad,” he said.
But Albert Rothenberg, professor of psychiatry at Harvard University is not convinced. He believes that there is no good evidence for a link between mental illness and creativity. “It’s the romantic notion of the 19th century, that the artist is the struggler, aberrant from society, and wrestling with inner demons,” he said. “But take Van Gogh. He just happened to be mentally ill as well as creative. For me, the reverse is more interesting: creative people are generally not mentally ill, but they use thought processes that are of course creative and different.”
If Van Gogh’s illness was a blessing, the artist certainly failed to see it that way. In one of his last letters, he voiced his dismay at the disorder he fought for so much of his life: “Oh, if I could have worked without this accursed disease - what things I might have done.”
In 2014, Rothernberg published a book, “Flight of Wonder: an investigation of scientific creativity”, in which he interviewed 45 science Nobel laureates about their creative strategies. He found no evidence of mental illness in any of them. He suspects that studies which find links between creativity and mental illness might be picking up on something rather different.
“The problem is that the criteria for being creative is never anything very creative. Belonging to an artistic society, or working in art or literature, does not prove a person is creative. But the fact is that many people who have mental illness do try to work in jobs that have to do with art and literature, not because they are good at it, but because they’re attracted to it. And that can skew the data,” he said. “Nearly all mental hospitals use art therapy, and so when patients come out, many are attracted to artistic positions and artistic pursuits.”
http://www.theguardian.co(...)y-and-mental-illness
Results imply creative people are 25% more likely to carry genes that raise risk of bipolar disorder and schizophrenia. But others argue the evidence is flimsy
A detail from Vincent van Gogh’s Self-portrait with Bandaged Ear, 1889. The artist himself expressed dismay at the impact his mental illness had on his work. Photograph: Peter Barritt/Getty Images/SuperStock RM
The ancient Greeks were first to make the point. Shakespeare raised the prospect too. But Lord Byron was, perhaps, the most direct of them all: “We of the craft are all crazy,” he told the Countess of Blessington, casting a wary eye over his fellow poets.
The notion of the tortured artist is a stubborn meme. Creativity, it states, is fuelled by the demons that artists wrestle in their darkest hours. The idea is fanciful to many scientists. But a new study claims the link may be well-founded after all, and written into the twisted molecules of our DNA.
In a large study published on Monday, scientists in Iceland report that genetic factors that raise the risk of bipolar disorder and schizophrenia are found more often in people in creative professions. Painters, musicians, writers and dancers were, on average, 25% more likely to carry the gene variants than professions the scientists judged to be less creative, among which were farmers, manual labourers and salespeople.
Kari Stefansson, founder and CEO of deCODE, a genetics company based in Reykjavik, said the findings, described in the journal Nature Neuroscience, point to a common biology for some mental disorders and creativity. “To be creative, you have to think differently,” he told the Guardian. “And when we are different, we have a tendency to be labelled strange, crazy and even insane.”
The scientists drew on genetic and medical information from 86,000 Icelanders to find genetic variants that doubled the average risk of schizophrenia, and raised the risk of bipolar disorder by more than a third. When they looked at how common these variants were in members of national arts societies, they found a 17% increase compared with non-members.
The researchers went on to check their findings in large medical databases held in the Netherlands and Sweden. Among these 35,000 people, those deemed to be creative (by profession or through answers to a questionnaire) were nearly 25% more likely to carry the mental disorder variants.
Stefansson believes that scores of genes increase the risk of schizophrenia and bipolar disorder. These may alter the ways in which many people think, but in most people do nothing very harmful. But for 1% of the population, genetic factors, life experiences and other influences can culminate in problems, and a diagnosis of mental illness.
“Often, when people are creating something new, they end up straddling between sanity and insanity,” said Stefansson. “I think these results support the old concept of the mad genius. Creativity is a quality that has given us Mozart, Bach, Van Gogh. It’s a quality that is very important for our society. But it comes at a risk to the individual, and 1% of the population pays the price for it.”
Stefansson concedes that his study found only a weak link between the genetic variants for mental illness and creativity. And it is this that other scientists pick up on. The genetic factors that raise the risk of mental problems explained only about 0.25% of the variation in peoples’ artistic ability, the study found. David Cutler, a geneticist at Emory University in Atlanta, puts that number in perspective: “If the distance between me, the least artistic person you are going to meet, and an actual artist is one mile, these variants appear to collectively explain 13 feet of the distance,” he said.
Most of the artist’s creative flair, then, is down to different genetic factors, or to other influences altogether, such as life experiences, that set them on their creative journey.
For Stefansson, even a small overlap between the biology of mental illness and creativity is fascinating. “It means that a lot of the good things we get in life, through creativity, come at a price. It tells me that when it comes to our biology, we have to understand that everything is in some way good and in some way bad,” he said.
But Albert Rothenberg, professor of psychiatry at Harvard University is not convinced. He believes that there is no good evidence for a link between mental illness and creativity. “It’s the romantic notion of the 19th century, that the artist is the struggler, aberrant from society, and wrestling with inner demons,” he said. “But take Van Gogh. He just happened to be mentally ill as well as creative. For me, the reverse is more interesting: creative people are generally not mentally ill, but they use thought processes that are of course creative and different.”
If Van Gogh’s illness was a blessing, the artist certainly failed to see it that way. In one of his last letters, he voiced his dismay at the disorder he fought for so much of his life: “Oh, if I could have worked without this accursed disease - what things I might have done.”
In 2014, Rothernberg published a book, “Flight of Wonder: an investigation of scientific creativity”, in which he interviewed 45 science Nobel laureates about their creative strategies. He found no evidence of mental illness in any of them. He suspects that studies which find links between creativity and mental illness might be picking up on something rather different.
“The problem is that the criteria for being creative is never anything very creative. Belonging to an artistic society, or working in art or literature, does not prove a person is creative. But the fact is that many people who have mental illness do try to work in jobs that have to do with art and literature, not because they are good at it, but because they’re attracted to it. And that can skew the data,” he said. “Nearly all mental hospitals use art therapy, and so when patients come out, many are attracted to artistic positions and artistic pursuits.”
http://www.theguardian.co(...)y-and-mental-illness
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
05-06-2015
Google-topman: "In 2030 zullen mensen hybride kunnen denken"
© thinkstock.
Technologie In de (nabije) toekomst zullen niet alleen robots, maar ook mensen over artificiële intelligentie beschikken, zo voorspelt Ray Kurzweil, ingenieur en innovatief denker bij Google. "In 2030 zullen we onze hersenen op the cloud kunnen aansluiten", zegt hij.
Volgens Google-topman Ray Kurzweil zullen ook mensen over een vijftiental jaar over de geneugten van artificiële intelligentie kunnen beschikken. "In 2030 zullen we onze hersenen rechtstreeks op de cloud kunnen aansluiten", zegt hij. In die cloud bevinden zich duizenden computers. Het gigantische volume aan kennis en digitaal opslagvermogen dat zich daar schuilhoudt, zal ervoor zorgen dat onze intelligentie een enorme sprong vooruit zal maken.
Hoe onze menselijke hersenen de verbinding met de digitale wereld precies zullen leggen? Met behulp van minuscule nanorobots, gemaakt van strengen uit het menselijk DNA.
Artificiële intelligentie
"Op die manier zal ons denken een combinatie worden van biologische en niet-biologische activiteiten", verklaart Kurzweil. Hoe groter en complexer de cloud zal worden, hoe geavanceerder ook ons denken. Volgens Kurzweil zal het digitale denken tegen 2040 zelfs zo ver gevorderd zijn dat het de gebruikelijke biologische vormen ervan nagenoeg volledig verdrongen heeft.
Back-up van onze hersenen
'Het voortdurend overschrijden van onze eigen grenzen, dat maakt volgens mij de essentie van ons menszijn uit'
Ray Kurzweil, ingenieur bij Google
Een van de grote voordelen van de biologische digitalisering is dat we - net zoals we dat vandaag doen bij onze laptop en computer - in de toekomst ook een back-up van onze hersenen zullen kunnen maken. Op die manier loopt ook onze persoonlijke kennis voortaan geen enkel risico meer om in rook op te gaan. "Door middel van technologische evolutie gaan we onszelf hoe langer hoe meer met het digitale laten samensmelten, en zullen we onszelf ook voortdurend verbeteren", merkt Kurzweil op. Volgens de futuroloog maakt die continue neiging om onze eigen grenzen te verleggen dan ook de essentie van ons menszijn uit.
Voorspellingen
Het is overigens niet de eerste keer dat de innovatieve Kurzweil dit soort voorspellingen over de toekomst doet. In de jaren '90 lijstte hij zo 147 verwachtingen voor 2009 op. In 2010 maakte hij de balans van die prognose op: ongeveer 86 procent van de voorziene evoluties waren werkelijkheid geworden. Zo voorspelde hij onder meer dat mensen in 2009 vooral gebruik zouden maken van draagbare computers, dat kabels nagenoeg verdwenen zouden zijn en dat er zelfs computerschermen in brilglazen zouden worden ingebouwd.
(HLN)
Google-topman: "In 2030 zullen mensen hybride kunnen denken"
© thinkstock.
Technologie In de (nabije) toekomst zullen niet alleen robots, maar ook mensen over artificiële intelligentie beschikken, zo voorspelt Ray Kurzweil, ingenieur en innovatief denker bij Google. "In 2030 zullen we onze hersenen op the cloud kunnen aansluiten", zegt hij.
Volgens Google-topman Ray Kurzweil zullen ook mensen over een vijftiental jaar over de geneugten van artificiële intelligentie kunnen beschikken. "In 2030 zullen we onze hersenen rechtstreeks op de cloud kunnen aansluiten", zegt hij. In die cloud bevinden zich duizenden computers. Het gigantische volume aan kennis en digitaal opslagvermogen dat zich daar schuilhoudt, zal ervoor zorgen dat onze intelligentie een enorme sprong vooruit zal maken.
Hoe onze menselijke hersenen de verbinding met de digitale wereld precies zullen leggen? Met behulp van minuscule nanorobots, gemaakt van strengen uit het menselijk DNA.
Artificiële intelligentie
"Op die manier zal ons denken een combinatie worden van biologische en niet-biologische activiteiten", verklaart Kurzweil. Hoe groter en complexer de cloud zal worden, hoe geavanceerder ook ons denken. Volgens Kurzweil zal het digitale denken tegen 2040 zelfs zo ver gevorderd zijn dat het de gebruikelijke biologische vormen ervan nagenoeg volledig verdrongen heeft.
Back-up van onze hersenen
'Het voortdurend overschrijden van onze eigen grenzen, dat maakt volgens mij de essentie van ons menszijn uit'
Ray Kurzweil, ingenieur bij Google
Een van de grote voordelen van de biologische digitalisering is dat we - net zoals we dat vandaag doen bij onze laptop en computer - in de toekomst ook een back-up van onze hersenen zullen kunnen maken. Op die manier loopt ook onze persoonlijke kennis voortaan geen enkel risico meer om in rook op te gaan. "Door middel van technologische evolutie gaan we onszelf hoe langer hoe meer met het digitale laten samensmelten, en zullen we onszelf ook voortdurend verbeteren", merkt Kurzweil op. Volgens de futuroloog maakt die continue neiging om onze eigen grenzen te verleggen dan ook de essentie van ons menszijn uit.
Voorspellingen
Het is overigens niet de eerste keer dat de innovatieve Kurzweil dit soort voorspellingen over de toekomst doet. In de jaren '90 lijstte hij zo 147 verwachtingen voor 2009 op. In 2010 maakte hij de balans van die prognose op: ongeveer 86 procent van de voorziene evoluties waren werkelijkheid geworden. Zo voorspelde hij onder meer dat mensen in 2009 vooral gebruik zouden maken van draagbare computers, dat kabels nagenoeg verdwenen zouden zijn en dat er zelfs computerschermen in brilglazen zouden worden ingebouwd.
(HLN)
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
09-06-2015
Bloed gevonden in fossielen van dinosauriërs
Geschreven door Tim Kraaijvanger op 9 juni 2015 om 19:17 uur
Wetenschappers hebben rode bloedcellen en proteïnen gevonden in de gefossiliseerde botten van dinosauriërs. Het is fascinerend dat bloed en andere cellen 75 miljoen jaar bewaard zijn gebleven.
De onderzoekers analyseerden acht botten van dino’s die in het Krijt leefden. Ze gebruikten een rasterelektronenmicroscoop om structuren op celniveau te bestuderen. In de klauw van een theropoda-dino vonden de wetenschappers ronde structuren: bloedcellen. Daarnaast troffen zij in vier andere fossielen vezels aan, die lijken op het eiwit collageen in botten van vogels.
Vervolgens gebruikten onderzoekers Sergio Bertazzo en Susie Maidment een ionstraal om bepaalde lagen één voor één weg te snijden. Ze ontdekten toen een interne structuur in de rode bloedcellen, die – op basis van de grootte en de vorm – vrijwel zeker een kern is. Ook spotte het duo aminozuren (de bouwstenen van proteïnen) die identiek zijn aan de aminozuren in levende emoes.
Collageen
Proteïnen gaan lang mee
Het is opvallend dat er proteïnen zijn gevonden, want uit eerder onderzoek is gebleken dat proteïnen niet langer dan vier miljoen jaar bewaard blijven. Deze ontdekking laat zien dat proteïnen veel langer meegaan. Een uitgebreid paper naar aanleiding van deze ontdekking is deze week te lezen in het wetenschappelijke blad Nature Communications.
En DNA?
De prangende vraag die veel mensen momenteel bezighoudt: is er ook DNA gevonden? Nee, de rode bloedcellen bevatten geen DNA en dat is jammer, want dankzij DNA zou een dino in de toekomst gekloond kunnen worden. Maar onderzoekers geven de moed niet op. “Het is niet uitgesloten dat er ergens ter wereld een goed bewaard dinobot ligt met DNA-fragmenten”, vertelt Maidment. Er is dus nog hoop voor fans van Jurassic Park.
Bijzondere vondsten
De afgelopen 25 jaar zijn wetenschappers steeds meer te weten gekomen over dinosaurussen. Zo zijn er resten gevonden van huid, gekleurde veren, kleurige organellen en zelfs spiervezels.
(scientias.nl)
Bloed gevonden in fossielen van dinosauriërs
Geschreven door Tim Kraaijvanger op 9 juni 2015 om 19:17 uur
Wetenschappers hebben rode bloedcellen en proteïnen gevonden in de gefossiliseerde botten van dinosauriërs. Het is fascinerend dat bloed en andere cellen 75 miljoen jaar bewaard zijn gebleven.
De onderzoekers analyseerden acht botten van dino’s die in het Krijt leefden. Ze gebruikten een rasterelektronenmicroscoop om structuren op celniveau te bestuderen. In de klauw van een theropoda-dino vonden de wetenschappers ronde structuren: bloedcellen. Daarnaast troffen zij in vier andere fossielen vezels aan, die lijken op het eiwit collageen in botten van vogels.
Vervolgens gebruikten onderzoekers Sergio Bertazzo en Susie Maidment een ionstraal om bepaalde lagen één voor één weg te snijden. Ze ontdekten toen een interne structuur in de rode bloedcellen, die – op basis van de grootte en de vorm – vrijwel zeker een kern is. Ook spotte het duo aminozuren (de bouwstenen van proteïnen) die identiek zijn aan de aminozuren in levende emoes.
Collageen
Proteïnen gaan lang mee
Het is opvallend dat er proteïnen zijn gevonden, want uit eerder onderzoek is gebleken dat proteïnen niet langer dan vier miljoen jaar bewaard blijven. Deze ontdekking laat zien dat proteïnen veel langer meegaan. Een uitgebreid paper naar aanleiding van deze ontdekking is deze week te lezen in het wetenschappelijke blad Nature Communications.
En DNA?
De prangende vraag die veel mensen momenteel bezighoudt: is er ook DNA gevonden? Nee, de rode bloedcellen bevatten geen DNA en dat is jammer, want dankzij DNA zou een dino in de toekomst gekloond kunnen worden. Maar onderzoekers geven de moed niet op. “Het is niet uitgesloten dat er ergens ter wereld een goed bewaard dinobot ligt met DNA-fragmenten”, vertelt Maidment. Er is dus nog hoop voor fans van Jurassic Park.
Bijzondere vondsten
De afgelopen 25 jaar zijn wetenschappers steeds meer te weten gekomen over dinosaurussen. Zo zijn er resten gevonden van huid, gekleurde veren, kleurige organellen en zelfs spiervezels.
(scientias.nl)
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
THE UNSEEN WOMEN SCIENTISTS BEHIND TIM HUNT'S NOBEL PRIZE
Women in science are either anonymous or reduced to stock pictures. We need to do more than condemn negative comments: we need to actively project positive portrayals. Photograph: DCPhoto /Alamy
This week, Professor Tim Hunt shocked the scientific community, and pretty much everyone else, with his outrageous comments about his “trouble with girls” and his backwards endorsement of gender-segregated laboratories, which are apparently needed because women are impossibly attracted to him. Understandably, commenters have slammed both his sexist comments and his apology. But the most important people in the story have been drowned out: the women scientists who are living proof of just how wrong Hunt is.
The field Hunt partly created, as well as his own scientific career, have both flourished due to his intellectual collaborations with women, as well as countless other academic partnerships between men and women, notably in the lab of Sir Paul Nurse. Tracing Hunt’s own history, his outburst seems even more astounding.
Hunt’s key breakthrough about the cell cycle, the discovery cyclins, centred on his experiments with sea urchins and clams in the Marine Biology Laboratory, Woods Hole. It was here that he worked extensively with Joan Ruderman, a period he later said “opened up new horizons, not only in learning to deal with new systems, but in the breadth of approaches and interests of scientists who passed through Woods Hole”. In his Nobel lecture, Hunt lauded the simple, but brilliant, experiments of Ruderman and Katherine Swenson, who were the first to show that cyclins bring about cell division. He described their experiments as “electrifying”, saying the women produced a “spectacular result” that “made people sit up and take note”. Admittedly, there are shamefully few women in Hunt’s personal “cell cycle story”, but he clearly respects their scientific insights and has directly benefitted from their input, making it extremely hard to understand why he thinks working with women is a waste of his time.
Tim Hunt shared that prestigious stage in Stockholm with Sir Paul Nurse, and they both could not have claimed place on that platform without the tireless efforts of women colleagues. As a member of Nurse’s lab, Melanie Lee proved that his work in yeast was applicable to humans, a revelation that captured the attention of the medical community. Nurse described it as “a major step forward, all the more so because she persevered with a project that many argued was highly unlikely to succeed”. Writing in the journal Cell, Professor Kim Nasmyth, FRS, praised Lee’s contribution as a “tour de force” that had “an immediate and electrifying impact”.
It’s no surprise that the Royal Society, headed by Nurse, so rapidly denounced Hunt’s sexist ramblings: their own figurehead’s career was launched into the stratosphere by a woman, and he enjoyed excellent working relationships with several women. Nurse’s first graduate student, Jacky Hayles, had been working in his laboratory for twenty years by the time he received his Nobel Prize. Nurse credited her numerous contributions to his science in his Nobel lecture, as well as the seminal work of Kathy Gould, who helped define the regulatory events triggering cell division.
Hunt calls women scientists “girls”, as though they are immature, and incapable of forwarding academia in any serious way. He suggests they disturb serious, hard-working men in their scientific pursuit. Yet Hunt knows women who have bolstered to his own success. He is obviously aware of the ground-breaking research women are doing in science; he is certainly more aware than any member of the public, and many of those criticising him. Is it that only some women are distractions, or maybe he thinks he would have won several Nobel Prizes if there were no women around?
It is obvious that his comments were sexist, but few people could recognise the names or faces of the women he has so thoughtlessly brushed aside. Even in his inadequate apology, he neglected to mention any women scientists who have impressed him during his career, choosing instead to justify himself with unsolicited details about his love life. Many have railed against Hunt’s casual chauvinism, without questioning why positive remarks about women are still missing. Would such comments be irrelevant? Unless we acknowledge the stories of women he has forgotten, a negative portrayal of women once again takes centre stage.
This is the mentality that breeds sexism in science, and indeed, everywhere. Hunt has become a symbol of a widespread problem; criticising him may galvanise feminists, but unless we project positive attitudes about women, sexism will remain the status quo. At the moment, stock pictures of teenagers holding test tubes, or maybe a picture of Rosalind Franklin, are our best representations of “women in science”. Women are either anonymous, or have only made headlines because they were ignored. This, of course, has to change, and not just in science.
In male-dominated fields, these changes will require leadership from both men as well as women. Men must help to empower their female colleagues, especially when the world is watching. This is perhaps the most depressing part of Hunt’s public downfall. He is in a unique position to call for progress on social attitudes in science, but has proved completely incapable of doing so.
http://www.theguardian.co(...)ts-nobel-prize#img-1
Women in science are either anonymous or reduced to stock pictures. We need to do more than condemn negative comments: we need to actively project positive portrayals. Photograph: DCPhoto /Alamy
This week, Professor Tim Hunt shocked the scientific community, and pretty much everyone else, with his outrageous comments about his “trouble with girls” and his backwards endorsement of gender-segregated laboratories, which are apparently needed because women are impossibly attracted to him. Understandably, commenters have slammed both his sexist comments and his apology. But the most important people in the story have been drowned out: the women scientists who are living proof of just how wrong Hunt is.
The field Hunt partly created, as well as his own scientific career, have both flourished due to his intellectual collaborations with women, as well as countless other academic partnerships between men and women, notably in the lab of Sir Paul Nurse. Tracing Hunt’s own history, his outburst seems even more astounding.
Hunt’s key breakthrough about the cell cycle, the discovery cyclins, centred on his experiments with sea urchins and clams in the Marine Biology Laboratory, Woods Hole. It was here that he worked extensively with Joan Ruderman, a period he later said “opened up new horizons, not only in learning to deal with new systems, but in the breadth of approaches and interests of scientists who passed through Woods Hole”. In his Nobel lecture, Hunt lauded the simple, but brilliant, experiments of Ruderman and Katherine Swenson, who were the first to show that cyclins bring about cell division. He described their experiments as “electrifying”, saying the women produced a “spectacular result” that “made people sit up and take note”. Admittedly, there are shamefully few women in Hunt’s personal “cell cycle story”, but he clearly respects their scientific insights and has directly benefitted from their input, making it extremely hard to understand why he thinks working with women is a waste of his time.
Tim Hunt shared that prestigious stage in Stockholm with Sir Paul Nurse, and they both could not have claimed place on that platform without the tireless efforts of women colleagues. As a member of Nurse’s lab, Melanie Lee proved that his work in yeast was applicable to humans, a revelation that captured the attention of the medical community. Nurse described it as “a major step forward, all the more so because she persevered with a project that many argued was highly unlikely to succeed”. Writing in the journal Cell, Professor Kim Nasmyth, FRS, praised Lee’s contribution as a “tour de force” that had “an immediate and electrifying impact”.
It’s no surprise that the Royal Society, headed by Nurse, so rapidly denounced Hunt’s sexist ramblings: their own figurehead’s career was launched into the stratosphere by a woman, and he enjoyed excellent working relationships with several women. Nurse’s first graduate student, Jacky Hayles, had been working in his laboratory for twenty years by the time he received his Nobel Prize. Nurse credited her numerous contributions to his science in his Nobel lecture, as well as the seminal work of Kathy Gould, who helped define the regulatory events triggering cell division.
Hunt calls women scientists “girls”, as though they are immature, and incapable of forwarding academia in any serious way. He suggests they disturb serious, hard-working men in their scientific pursuit. Yet Hunt knows women who have bolstered to his own success. He is obviously aware of the ground-breaking research women are doing in science; he is certainly more aware than any member of the public, and many of those criticising him. Is it that only some women are distractions, or maybe he thinks he would have won several Nobel Prizes if there were no women around?
It is obvious that his comments were sexist, but few people could recognise the names or faces of the women he has so thoughtlessly brushed aside. Even in his inadequate apology, he neglected to mention any women scientists who have impressed him during his career, choosing instead to justify himself with unsolicited details about his love life. Many have railed against Hunt’s casual chauvinism, without questioning why positive remarks about women are still missing. Would such comments be irrelevant? Unless we acknowledge the stories of women he has forgotten, a negative portrayal of women once again takes centre stage.
This is the mentality that breeds sexism in science, and indeed, everywhere. Hunt has become a symbol of a widespread problem; criticising him may galvanise feminists, but unless we project positive attitudes about women, sexism will remain the status quo. At the moment, stock pictures of teenagers holding test tubes, or maybe a picture of Rosalind Franklin, are our best representations of “women in science”. Women are either anonymous, or have only made headlines because they were ignored. This, of course, has to change, and not just in science.
In male-dominated fields, these changes will require leadership from both men as well as women. Men must help to empower their female colleagues, especially when the world is watching. This is perhaps the most depressing part of Hunt’s public downfall. He is in a unique position to call for progress on social attitudes in science, but has proved completely incapable of doing so.
http://www.theguardian.co(...)ts-nobel-prize#img-1
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
June 10, 2015
ANCIENT DNA REVEALS HOW EUROPEANS DEVELOPED LIGHT SKIN AND LACTOSE TOLERANCE
Slurp and thank the Yamnaya.
Food intolerance is often dismissed as a modern invention and a “first-world problem”. However, a study analysing the genomes of 101 Bronze-Age Eurasians reveals that around 90% were lactose intolerant.
The research also sheds light on how modern Europeans came to look the way they do – and that these various traits may originate in different ancient populations. Blue eyes, it suggests, could come from hunter gatherers in Mesolithic Europe (10,000 to 5,000 BC), while other characteristics arrived later with newcomers from the East.
About 40,000 years ago, after modern humans spread from Africa, one group moved north and came to populate Europe as well as north, west and central Asia. Today their descendants are still there and are recognisable by some very distinctive characteristics. They have light skin, a range of eye and hair colours and nearly all can happily drink milk.
However, exactly when and where these characteristics came together has been anyone’s guess. Until now.
CLASH OF CULTURES
Throughout history, there has been a pattern of cultures rising, evolving and being superseded. Greek, Roman and Byzantine cultures each famously had their 15 minutes as top dog. And archaeologists have defined a succession of less familiar cultures that rose and fell before that, during the Bronze Age. So far it has been difficult to work out which of these cultures gave rise to which – and eventually to today’s populations.
The Bronze Age (around 3,000–1,000 BC) was a time of major advances, and whenever one culture developed a particularly advantageous set of technologies, they become able to support a larger population and to dominate their neighbours. The study found that the geographical distributions of genetic variations at the beginning of the Bronze Age looked very different to today’s, but by the end it looked pretty similar, suggesting a level of migration and replacement of peoples not seen in western Eurasia since.
One people that was particularly important in the spread of both early Bronze-Age technologies and genetics were the Yamnaya. With a package of technologies including the horse and the wheel, they exploded out of the Russian and Ukrainian Steppe into Europe, where they met the local Neolithic farmers.
Yamnaya skull
By comparing DNA from various Bronze-Age European cultures to that of both Yamnaya and the Neolithic farmers, researchers found that most had a mixture of the two backgrounds. However the proportions varied, with the Corded Ware people of northern Europe having the highest proportion of Yamnaya ancestry.
And it appears that the Yamnaya also moved east. The Afanasievo culture of the Altai-Sayan region in central Asia seemed to be genetically indistinguishable from the Yamnaya, suggesting a colonisation with little or no interbreeding with pre-existing populations.
MUTATIONS TRACED
So how have traits that were rare or non-existent in our African ancestors come to be so common in western Eurasia?
The DNA of several hunter gatherers living in Europe long before the Bronze Age was also tested. It showed that they probably had a combination of features quite striking to the modern eye: dark skin with blue eyes.
The blue eyes of these people – and of the many modern Europeans who have them – are thanks to a specific mutation near a gene called OCA2. As none of the Yamnaya samples have this mutation, it seems likely that modern Europeans owe this trait to their ancestry from these European hunter gatherers of the Mesolithic (10,000-5,000 BC).
Reconstruction of a Yamnaya person from the Caspian steppe in Russia about 5,000-4,800 BC.
Two mutations responsible for light skin, however, tell quite a different story. Both seem to have been rare in the Mesolithic, but present in a large majority by the Bronze Age (3,000 years later), both in Europe and the steppe. As both areas received a significant influx of Middle Eastern farmers during this time, one might speculate that the mutations arose in the Middle East. They were probably then driven to high levels by natural selection, as they allowed the production of sufficient vitamin D further north despite relatively little sunlight, and/or better suited people to the new diet associated with farming.
Another trait that is nearly universal in modern Europeans (but not around the world) is the ability to digest the lactose in milk into adulthood. As cattle and other livestock have been farmed in western Eurasia since long before, one might expect such a mutation to already be widespread by the Bronze Age. However the study revealed that the mutation was found in around 10% of their Bronze Age samples.
Interestingly, the cultures with the most individuals with this mutation were the Yamnaya and their descendents. These results suggest that the mutation may have originated on the steppe and entered Europe with the Yamnaya. A combination of natural selection working on this advantageous trait and the advantageous Yamnaya culture passed down alongside it could then have helped it spread, although this process still had far to go during the bronze age.
This significant study has left us with a much more detailed picture of Bronze Age Europeans: they had the light skin and range of eye colours we know today. And although most would have got terrible belly ache from drinking milk, the seeds for future lactose tolerance were sown and growing.
https://theconversation.c(...)tose-tolerance-43078
ANCIENT DNA REVEALS HOW EUROPEANS DEVELOPED LIGHT SKIN AND LACTOSE TOLERANCE
Slurp and thank the Yamnaya.
Food intolerance is often dismissed as a modern invention and a “first-world problem”. However, a study analysing the genomes of 101 Bronze-Age Eurasians reveals that around 90% were lactose intolerant.
The research also sheds light on how modern Europeans came to look the way they do – and that these various traits may originate in different ancient populations. Blue eyes, it suggests, could come from hunter gatherers in Mesolithic Europe (10,000 to 5,000 BC), while other characteristics arrived later with newcomers from the East.
About 40,000 years ago, after modern humans spread from Africa, one group moved north and came to populate Europe as well as north, west and central Asia. Today their descendants are still there and are recognisable by some very distinctive characteristics. They have light skin, a range of eye and hair colours and nearly all can happily drink milk.
However, exactly when and where these characteristics came together has been anyone’s guess. Until now.
CLASH OF CULTURES
Throughout history, there has been a pattern of cultures rising, evolving and being superseded. Greek, Roman and Byzantine cultures each famously had their 15 minutes as top dog. And archaeologists have defined a succession of less familiar cultures that rose and fell before that, during the Bronze Age. So far it has been difficult to work out which of these cultures gave rise to which – and eventually to today’s populations.
The Bronze Age (around 3,000–1,000 BC) was a time of major advances, and whenever one culture developed a particularly advantageous set of technologies, they become able to support a larger population and to dominate their neighbours. The study found that the geographical distributions of genetic variations at the beginning of the Bronze Age looked very different to today’s, but by the end it looked pretty similar, suggesting a level of migration and replacement of peoples not seen in western Eurasia since.
One people that was particularly important in the spread of both early Bronze-Age technologies and genetics were the Yamnaya. With a package of technologies including the horse and the wheel, they exploded out of the Russian and Ukrainian Steppe into Europe, where they met the local Neolithic farmers.
Yamnaya skull
By comparing DNA from various Bronze-Age European cultures to that of both Yamnaya and the Neolithic farmers, researchers found that most had a mixture of the two backgrounds. However the proportions varied, with the Corded Ware people of northern Europe having the highest proportion of Yamnaya ancestry.
And it appears that the Yamnaya also moved east. The Afanasievo culture of the Altai-Sayan region in central Asia seemed to be genetically indistinguishable from the Yamnaya, suggesting a colonisation with little or no interbreeding with pre-existing populations.
MUTATIONS TRACED
So how have traits that were rare or non-existent in our African ancestors come to be so common in western Eurasia?
The DNA of several hunter gatherers living in Europe long before the Bronze Age was also tested. It showed that they probably had a combination of features quite striking to the modern eye: dark skin with blue eyes.
The blue eyes of these people – and of the many modern Europeans who have them – are thanks to a specific mutation near a gene called OCA2. As none of the Yamnaya samples have this mutation, it seems likely that modern Europeans owe this trait to their ancestry from these European hunter gatherers of the Mesolithic (10,000-5,000 BC).
Reconstruction of a Yamnaya person from the Caspian steppe in Russia about 5,000-4,800 BC.
Two mutations responsible for light skin, however, tell quite a different story. Both seem to have been rare in the Mesolithic, but present in a large majority by the Bronze Age (3,000 years later), both in Europe and the steppe. As both areas received a significant influx of Middle Eastern farmers during this time, one might speculate that the mutations arose in the Middle East. They were probably then driven to high levels by natural selection, as they allowed the production of sufficient vitamin D further north despite relatively little sunlight, and/or better suited people to the new diet associated with farming.
Another trait that is nearly universal in modern Europeans (but not around the world) is the ability to digest the lactose in milk into adulthood. As cattle and other livestock have been farmed in western Eurasia since long before, one might expect such a mutation to already be widespread by the Bronze Age. However the study revealed that the mutation was found in around 10% of their Bronze Age samples.
Interestingly, the cultures with the most individuals with this mutation were the Yamnaya and their descendents. These results suggest that the mutation may have originated on the steppe and entered Europe with the Yamnaya. A combination of natural selection working on this advantageous trait and the advantageous Yamnaya culture passed down alongside it could then have helped it spread, although this process still had far to go during the bronze age.
This significant study has left us with a much more detailed picture of Bronze Age Europeans: they had the light skin and range of eye colours we know today. And although most would have got terrible belly ache from drinking milk, the seeds for future lactose tolerance were sown and growing.
https://theconversation.c(...)tose-tolerance-43078
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
MICROSOFT IS BUILDING A DRONE ARMY TO CATCH MOSQUITOES AND STOP EPIDEMICS
It could predict new diseases before they infect humans.
DAVID NIELD 16 JUN 2015
One potential use for drones that you might not have thought about is preventing the spread of disease. Microsoft has just launched an initiative called Project Premonition, with the aim of detecting viruses before they infect a significant number of people using a fleet of Unmanned Aerial Vehicles (or UAVs).
In remote areas where dengue fever or malaria can take hold, the impact of drone technology and number of saved lives could be huge. The key is in catching mosquitoes and analysing the diseases they're carrying: "The mosquito is the most dangerous animal on the planet, because it carries so many pathogens," Microsoft researcher Ethan Jackson, who is leading Project Premonition, told Allison Linn over on the company's blog. "What we want to do is to be able to catch that mosquito efficiently, at scale and at low cost."
Right now, scientists attempt to do this by using traps hung from trees that must be collected by hand. But Microsoft's new plan could greatly speed up this process and make it a lot cheaper, by sending out portable drones that are able to cover far more distance and come back to base with bigger samples.
This would allow scientists to not only monitor the spread of known diseases carried by mosquitoes, but also detect emerging viruses and epidemics before they begin to spread. To do this, they're developing software that will be able to quickly and accurately process genetic data collected by their mosquito-hunting UAV fleet, giving researchers a better idea of the viruses that are out there and how they're spreading.
It all sounds a little far fetched, but Microsoft carried out a feasibility study in Grenada in the Caribbean in March, and presented its findings at the Microsoft Innovation TechFair in Washington, DC last week. The company now says it's working with academic partners across multiple disciplines to make Project Premonition a reality within the next five years.
Getting advance warning of a potential epidemic is crucial in stopping or limiting it. Vaccines and health clinics can be up and running earlier, and any necessary travelling restrictions can be put in place before the situation worsens. "The ability to predict an epidemic would be huge," Douglas Norris, a professor of molecular microbiology and immunology at Johns Hopkins Bloomberg School of Public Health in Maryland, told Linn.
As part of his work, Norris often finds himself working in remote areas using mosquito traps that haven't changed much since the 1950s or 60s. They use expensive batteries and chemicals that are difficult to source, and indiscriminately collect plenty other bugs besides mosquitoes - there's huge room for improvement in terms of the technology and its efficiency, and that's where Project Premonition comes in.
In order for the scheme to be a success, the drones will need to operate semi-autonomously as well as being directed by a human pilot: having the ability to navigate environments on their own ensures they can travel greater distances and cover more land. All that extra functionality requires more research and programming of course, but the Project Premonition team is optimistic about its chances. Mirosoft is also developing these mosquito traps, which will be attached to the drones:
What's more, thanks to the latest advancements in molecular biology and genetic sequencing, samples can be processed faster and more cheaply than ever - they can even spot viruses that haven't been classified yet. By developing cloud databases and algorithms to store all of this data, the researchers behind Project Premonition hope to build a robust system capable of spotting dangers to humans and wildlife alike in the future.
http://www.sciencealert.c(...)s-and-stop-epidemics
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
SCIENTISTS DISCOVER FUNDAMENTAL PROPERTY OF LIGHT
And here's how we can harness it.
CLIVE EMARY, THE CONVERSATION 2 JUL 2015
This article was written by Clive Emary from the University of Hull, and was originally published by The Conversation.
Light plays a vital role in our everyday lives and technologies based on light are all around us. So we might expect that our understanding of light is pretty settled. But scientists have just uncovered a new fundamental property of light that gives new insight into the 150-year-old classical theory of electromagnetism and which could lead to applications manipulating light at the nanoscale.
It is unusual for a pure-theory physics paper to make it into the journal Science. So when one does, it’s worth a closer look. In the new study, researchers bring together one of physics' most venerable set of equations - those of James Clerk’s Maxwell’s famous theory of light - with one of the hot topics in modern solid-state physics: the quantum spin Hall effect and topological insulators.
To understand what the fuss is about, let’s first consider the behaviour of electrons in the quantum spin Hall effect. Electrons possess an intrinsic spin as if they were tiny spinning-tops, constantly rotating about their axis. This spin is a quantum-mechanical property, however, and special rules apply - the electron has only two options open to it: it can either spin clockwise or anticlockwise (conventionally called spin-up or spin-down), but the magnitude of the spin is always fixed.
In certain materials, the spin of the electron can have a big effect on the way electrons move. This effect is called "spin-orbit coupling" and we can get an idea of how it works with a footballing analogy. By hitting a freekick with spin, a footballer can make the ball deviate to the left or the right as it travels through the air. The direction of the movement depends on which way the ball is spinning.
Spin-orbit coupling causes electrons to experience an analogous spin-dependent deflection as they travel, although the effect arises not from the Magnus effect as in the case for the football, but from electric fields within the material.
A normal electrical current consists of an equal mixture of moving spin-up and spin-down electrons. Due to the spin-orbit effect, spin-up electrons will be deflected one way, while spin-down electrons will be deflected the other. Eventually the deflected electrons will reach the edges of the material and be able to travel no further. The spin-orbit coupling thus leads to an accumulation of electrons with different spins on opposite sides of the sample.
This effect is known as the classical spin Hall effect, and quantum mechanics adds a dramatic twist on top. The quantum-mechanical wave nature of the travelling electrons organises them into neat channels along the edges of the sample. In the bulk of the material, there is no net spin. But at each edge, there form exactly two electron-carrying channels, one for spin-up electrons and one for spin-down. These edge channels possess a further remarkable property: the electrons that move in them are impervious to the disorder and imperfections that usually cause resistance and energy loss.
This precise ordering of the electrons into spin-separated, perfectly conducting channels is known as the quantum spin Hall effect, which is a classic example of a “topological insulator”– a material that is an electrical insulator on the inside but that can conduct electricity on its surface. Such materials represent a fundamentally distinct organisation of matter and promise much in the way of spintronic applications. Read heads of hard drives based on this technology are currently used in industry.
BEGINNING TO SEE THE LIGHT
Now, the new study suggests that the seeds of this seemingly exotic quantum spin Hall effect are actually all around us. And it is not to electrons that we should look to find them, but rather to light itself.
In modern physics, matter can be described either as a wave or a particle. In Maxwell’s theory, light is an electromagnetic wave. This means it travels as a synchronised oscillation of electric and magnetic fields. By considering the way in which these fields rotate as the wave propagates, the researchers were able to define a property of the wave, the "transverse spin", that plays the role of the electron spin in the quantum spin Hall effect.
In a homogeneous medium, like air, this spin is exactly zero. However, at the interface between two media (air and gold, for example), the character of the waves change dramatically and a transverse spin develops. Furthermore, the direction of this spin is precisely locked to the direction of travel of the light wave at the interface. Thus, when viewed in the correct way, we see that the basic topological ingredients of the quantum spin Hall effect that we know for electrons are shared by light waves.
This is important because there has been an array of high-profile experiments demonstrating coupling between the spin of light and its direction of propagation at surfaces. This new work gives a integrative interpretation of these experiments as revealing light’s intrinsic quantum spin Hall effect. It also points to a certain universality in the behaviour of waves at surfaces, be they quantum-mechanical electron waves or Maxwell’s classical waves of light.
Harnessing the spin-orbit effect will open new possibilities for controlling light at the nanoscale. Optical connections, for example, are seen as a way of increasing computer performance, and in this context, the spin-orbit effect could be used to rapidly reroute optical signals based on their spin. With applications proposed in optical communications, metrology, and quantum information processing, it will be interesting to see how the impact of this new twist on an old theory unfolds.
Clive Emary is lecturer in physics at University of Hull.
http://www.sciencealert.c(...)al-property-of-light
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
THIS IS THE WAY THE WORLD ENDS: NOT WITH A BANG, BUT WITH A BIG RIP
New model suggests that as the universe expands everything from galaxies to space-time itself will be torn apart - but not for about 22 billion years
The end of the world (and indeed the universe) as we know it won’t be an explosion but a separation of the constituents of all matter, say scientists at Vanderbilt University. Photograph: Ace Stock Limited/Alamy
Everything we know, and everything else besides, burst into existence at the Big Bang. Now scientists have concluded that we could be heading for an equally dramatic cosmic finale: the Big Rip.
A new theoretical model suggests that as the universe expands, everything, from galaxies, planets and atomic particles to space-time itself, will eventually be torn apart before vanishing from view.
There’s no need for immediate alarm, however: the extreme sequence of events is predicted for around 22 billion years from now.
Dr Marcelo Disconzi, the mathematician who led the work at Vanderbilt University in Tennessee, said: “The idea of the Big Rip is that eventually even the constituents of matter would start separating from each other. You’d be seeing all the atoms being ripped apart ... it’s fair to say that it’s a dramatic scenario.”
Scientists are now fairly convinced that the universe began with the Big Bang, around 13.8 billion years ago – starting at a pinpoint of incredibly high density and expanding to what we have today.
But our ultimate cosmic destiny is still the subject of intense debate.
“The only thing we definitely know is that the universe is expanding and that the rate is accelerating,” said Disconzi. “That’s about the only thing we know for sure.”
The latest work suggests that this acceleration may become faster and faster until every point in space itself is moving apart at an infinite rate – at which point the Big Rip occurs.
The timeline of the universe, from Big Bang to Big Rip, according to the new theory. Photograph: Jeremy Teaford, Vanderbilt University
“Mathematically we know what this means,” said Disconzi. “But what it actually means in physical terms is hard to fathom.”
The evidence for an accelerating expansion comes from observations of distant supernovae. The further away they are the redder they appear, because the light has been stretched out as it travels through space to reach us.
To explain this increasing rate of expansion, scientists have come up with a cosmological placeholder, known as dark energy, which is believed to make up about 70% of the content of the universe.
“It’s the physicists’ way to hide their ignorance by giving it a mysterious name,” said Professor Carlos Frenk, a cosmologist at the University of Durham. “We don’t have any physically compelling way to explain it.”
Whether the universe’s expansion continues to speed up or gradually eases off comes down to a sort of gladiatorial battle between two opposing cosmic forces.
“You have this competition between dark energy, that tries to expand the universe, and gravity, that tends to make it collapse again,” said Disconzi. The question is who wins?”
Under the gravity wins scenario, known as the Big Crunch, the expansion eventually slows down and a kind of reverse of the Big Bang occurs.
But scientists have been shifting in favour of a situation called the Big Freeze where the universe continues to expand, eventually growing so vast that supplies of gas become too thin for new stars to form and a thin soup of radiation is left. Eventually this cools down to the point where time loses any meaning because nothing happens any more.
The latest work suggests that we could be heading for less a gentle finale, and predicts that dark energy wins out in the most dramatic possible fashion.
The paper, published in the journal Physical Review D, refines current models by finding a more consistent way to account for a property called bulk viscosity, a measure of a fluid’s ability to expand or contract. In this case, the fluid is the universe itself.
Previously, according to Disconzi, viscosity had been included in the equations but in a way that predicted that under certain conditions fluids could travel faster than light.
“This is disastrously wrong, since it is well-proven that nothing can travel faster than the speed of light,” said Disconzi.
The latest formulation gets rid of this inconsistency, but also gives a revised prediction of where the Universe is heading, suggesting that eventually the expansion of the universe will accelerate at an infinite rate.
“A Big Rip scenario is a natural consequence of the equations,” said Disconzi.
One way to think of the lead-up to the event, is a speeding car that goes 10mph faster for every mile it travels. But the rate of acceleration gradually increases until it goes 10mph faster for every half mile, and then every quarter of a mile and eventually every foot. Ultimately, the front and the back bumpers tear apart from each other and then rip apart themselves.
Whether this occurs in the cosmic version depends on how dark energy behaves in the distant future - a question that Frenk describes as the realm of pure speculation.
“Under the rip scenario, dark energy gets stronger and you get this wild expansion that essentially rips space-time apart,” he added. “The universe would vanish in front of your eyes. Basically, you don’t want to be around for it.”
http://www.theguardian.co(...)world-will-end#img-2
New model suggests that as the universe expands everything from galaxies to space-time itself will be torn apart - but not for about 22 billion years
The end of the world (and indeed the universe) as we know it won’t be an explosion but a separation of the constituents of all matter, say scientists at Vanderbilt University. Photograph: Ace Stock Limited/Alamy
Everything we know, and everything else besides, burst into existence at the Big Bang. Now scientists have concluded that we could be heading for an equally dramatic cosmic finale: the Big Rip.
A new theoretical model suggests that as the universe expands, everything, from galaxies, planets and atomic particles to space-time itself, will eventually be torn apart before vanishing from view.
There’s no need for immediate alarm, however: the extreme sequence of events is predicted for around 22 billion years from now.
Dr Marcelo Disconzi, the mathematician who led the work at Vanderbilt University in Tennessee, said: “The idea of the Big Rip is that eventually even the constituents of matter would start separating from each other. You’d be seeing all the atoms being ripped apart ... it’s fair to say that it’s a dramatic scenario.”
Scientists are now fairly convinced that the universe began with the Big Bang, around 13.8 billion years ago – starting at a pinpoint of incredibly high density and expanding to what we have today.
But our ultimate cosmic destiny is still the subject of intense debate.
“The only thing we definitely know is that the universe is expanding and that the rate is accelerating,” said Disconzi. “That’s about the only thing we know for sure.”
The latest work suggests that this acceleration may become faster and faster until every point in space itself is moving apart at an infinite rate – at which point the Big Rip occurs.
The timeline of the universe, from Big Bang to Big Rip, according to the new theory. Photograph: Jeremy Teaford, Vanderbilt University
“Mathematically we know what this means,” said Disconzi. “But what it actually means in physical terms is hard to fathom.”
The evidence for an accelerating expansion comes from observations of distant supernovae. The further away they are the redder they appear, because the light has been stretched out as it travels through space to reach us.
To explain this increasing rate of expansion, scientists have come up with a cosmological placeholder, known as dark energy, which is believed to make up about 70% of the content of the universe.
“It’s the physicists’ way to hide their ignorance by giving it a mysterious name,” said Professor Carlos Frenk, a cosmologist at the University of Durham. “We don’t have any physically compelling way to explain it.”
Whether the universe’s expansion continues to speed up or gradually eases off comes down to a sort of gladiatorial battle between two opposing cosmic forces.
“You have this competition between dark energy, that tries to expand the universe, and gravity, that tends to make it collapse again,” said Disconzi. The question is who wins?”
Under the gravity wins scenario, known as the Big Crunch, the expansion eventually slows down and a kind of reverse of the Big Bang occurs.
But scientists have been shifting in favour of a situation called the Big Freeze where the universe continues to expand, eventually growing so vast that supplies of gas become too thin for new stars to form and a thin soup of radiation is left. Eventually this cools down to the point where time loses any meaning because nothing happens any more.
The latest work suggests that we could be heading for less a gentle finale, and predicts that dark energy wins out in the most dramatic possible fashion.
The paper, published in the journal Physical Review D, refines current models by finding a more consistent way to account for a property called bulk viscosity, a measure of a fluid’s ability to expand or contract. In this case, the fluid is the universe itself.
Previously, according to Disconzi, viscosity had been included in the equations but in a way that predicted that under certain conditions fluids could travel faster than light.
“This is disastrously wrong, since it is well-proven that nothing can travel faster than the speed of light,” said Disconzi.
The latest formulation gets rid of this inconsistency, but also gives a revised prediction of where the Universe is heading, suggesting that eventually the expansion of the universe will accelerate at an infinite rate.
“A Big Rip scenario is a natural consequence of the equations,” said Disconzi.
One way to think of the lead-up to the event, is a speeding car that goes 10mph faster for every mile it travels. But the rate of acceleration gradually increases until it goes 10mph faster for every half mile, and then every quarter of a mile and eventually every foot. Ultimately, the front and the back bumpers tear apart from each other and then rip apart themselves.
Whether this occurs in the cosmic version depends on how dark energy behaves in the distant future - a question that Frenk describes as the realm of pure speculation.
“Under the rip scenario, dark energy gets stronger and you get this wild expansion that essentially rips space-time apart,” he added. “The universe would vanish in front of your eyes. Basically, you don’t want to be around for it.”
http://www.theguardian.co(...)world-will-end#img-2
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
A BLACK HOLE HAS BEEN CAUGHT BURPING OUT X-RAYS
Astronomers have spotted short bursts of X-rays coming from a black hole, suggesting it has become more active
Black holes are hungry. They grow bigger as they gobble up cosmic debris from nearby stars. Anything too close can get sucked in.
They are the remains of massive stars, scrunched up on themselves until they become infinitely dense. Anything that gets too close gets trapped by their powerful gravity. Even light cannot escape once it passes a critical point, the "event horizon".
That makes them hard to spot. Often the best way is to monitor the movements of nearby stars.
However, one black hole has recently made itself thoroughly conspicuous. After lying dormant for 26 years, it has begun emitting a series of bright cosmic burps.
We don't know what's inside a black hole (Credit: NASA/JPL-Caltech)
The first of these "X-ray novas" was observed two weeks ago. Astronomers monitoring the Swift telescope noticed that a strange new bright object had appeared in the sky.
At first the team didn't know what these bright flashes were. They alerted their colleagues, and several other telescopes began monitoring the flares. Some lasted several minutes, others went on for hours.
The astronomers have now found that the flares are coming from an intensely hot disk around the black hole.
This is happening because the black hole is consuming gas and dust from a nearby star, but not all of this stuff is going in. Instead, some of the material forms a ring around the black hole, called an accretion disk. You can see a simulation of this below.
This ring builds up over time, says Swift's director of mission operations John Nousek of Penn State University in Philadelphia, US.
"When it builds up enough material, you get a condition that looks very similar to when a hydrogen bomb has exploded," says Nousek. "A lot of hydrogen under intense pressure and heat makes an explosion that looks like a new star."
This blast is so powerful, it blows away all of the material that had been resting near the black hole.
The black hole pulls matter from its neighbouring star (Credit: NASA/CXC/M.Weiss)
These types of eruptions are rarely observed.
"Some kind of hiccup happened a couple of weeks ago and suddenly the star has started spewing gas onto the black hole," says Neil Gehrels of NASA's Goddard Space Flight Center in Maryland, US.
Observing these explosions helps researchers learn more about how black holes change over time.
They don't have long. As quickly as the eruptions began, they have now stopped. The black hole has gone back to sleep and we don't know when it will wake up again.
http://www.bbc.com/earth/(...)hole-has-cosmic-burp
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
MONKEY 'BRAIN NET' RAISES PROSPECT OF HUMAN BRAIN-TO-BRAIN CONNECTION
In two separate experiments, scientists have formed a network from the brains of monkeys and rats, allowing them to co-operate and learn as a “superbrain”
Although science fiction hive minds are often terrifying, as The Borg in Star Trek, the scientists behind the “brain net” experiments believe it has many positive applications. Photograph: Cinetext/Sportsphoto Ltd./Allstar
Scientists have linked together the brains of three monkeys, allowing the animals to join forces and control an avatar arm, in research that raises the prospect of direct brain-to-brain interfaces in humans.
In a second experiment, the brains of four rats were wired together in a “brain net”, enabling the rodents to synchronise their neuronal activity and collaboratively solve a simple weather forecasting problem that individual rats struggled to complete.
The experiments, which have echoes of the Borg, a sinister alien collective in Star Trek, challenge the notion that our minds will always be ultimately isolated from those of others.
Miguel Nicolelis, the Duke University scientist behind the work, has previously pioneered the development of brain-machine interfaces that could allow amputees and paralysed people to directly control prosthetic limbs and exoskeletons. His latest advance may have clinical benefits in brain rehabilitation, he predicts, but could also pave the way for “organic computers” - collectives of animal brains linked together to solve problems.
“Essentially we created a super-brain,” he said. “A collective brain created from three monkey brains. Nobody has ever done that before.”
He dismissed comparisons with science fiction plots, however, saying: “We’re conditioned by movies and Hollywood to think that everything related to science is dangerous and scary. These scary scenarios never crossed my mind and I’m the one doing the experiments.”
Anders Sandberg, a neuroethics researcher at the University of Oxford, said the work was the most convincing demonstration yet that brains can be linked together in direct communication. “People have claimed digital telepathy in various cool demos, but it’s mostly been total hype,” he said. “I’m quite impressed by this. It has a high ‘gosh’ factor.”
In the first study, scientists fitted three rhesus macaque monkeys with arrays that could record electrical activity from hundreds of neurons in the motor region of the brain.
The monkeys learnt, independently, to control the 3D movements of an avatar arm shown on a digital display in front of them, just by imagining moving it. The monkeys were then given joint control of the arm, with each monkey able to control two out of three dimensions (for instance, along the x- and y-axis) and their activity made a 50% contribution to each.
Although their brains were not directly wired together, the monkeys intuitively started to synchronise their brain activity, allowing them to move the arm collaboratively to a reach for a virtual ball on the screen.
The system appeared to work, even if one of the three monkeys was temporarily distracted. “Even if one monkey dropped out in one trial, the brain net is resilient,” said Nicolelis. “Imagine if you had, not three, but a million. That would be extremely resilient.”
In a second paper, also published in the journal Scientific Reports, the scientists directly linked the brains of rats together via two-way electrical connections that allowed the scientists to both deliver stimulus to neurons and read out electrical activity.
In one experiment, an electrical impulse was delivered to the brain of one rat, and the other rats learnt to synchronise their brain activity, mimicking the first rat’s brain response. In a sense, they were experiencing what the first rat felt, second-hand.
In another demonstration, pulses of stimulation that increased or decreased were delivered to the brains of individual rats, representing temperature and barometric pressure information. The rats were able to combine the information to produce a collective output that predicted an increased or decreased chance of rain. Rats scored better on this task when they were linked as a “brain net”, than when individual rats tried to combine the two pieces of initial information – temperature and pressure – to perform the simple calculation alone.
The scientists said that in the future, the concept might be extended to produce neurally connected “swarms” of rats with collective intelligence.
Nicolelis said that in the long-term the work could have “tremendous benefits” for brain rehabilitation. After suffering a stroke, for instance, language abilities might be able to be restored more quickly if a patient’s brain was retrained by directly synchronising with the language regions of the brain of a healthy person. In humans, the link could potentially be made non-invasively using electrodes on the scalp, however.
But he added it was unlikely that humans would ever be able to directly share complex mental experiences. “You’re not going to share your emotions or personality to a brain-net,” he said. “These are not reducible to a digital algorithm. You can’t reproduce these individual human attributes.”
Ultimately, people may also decide that wiring themselves up with others is not entirely desirable. “There may be special instances where you’d want a long-term connection with someone – like a married couple or a military platoon,” said Sandberg. “But there’s no guarantee that brain-to-brain interfaces will be a sensible thing in practice. There’s something to be said for neural privacy.”
http://www.theguardian.co(...)ain-connection#img-1
In two separate experiments, scientists have formed a network from the brains of monkeys and rats, allowing them to co-operate and learn as a “superbrain”
Although science fiction hive minds are often terrifying, as The Borg in Star Trek, the scientists behind the “brain net” experiments believe it has many positive applications. Photograph: Cinetext/Sportsphoto Ltd./Allstar
Scientists have linked together the brains of three monkeys, allowing the animals to join forces and control an avatar arm, in research that raises the prospect of direct brain-to-brain interfaces in humans.
In a second experiment, the brains of four rats were wired together in a “brain net”, enabling the rodents to synchronise their neuronal activity and collaboratively solve a simple weather forecasting problem that individual rats struggled to complete.
The experiments, which have echoes of the Borg, a sinister alien collective in Star Trek, challenge the notion that our minds will always be ultimately isolated from those of others.
Miguel Nicolelis, the Duke University scientist behind the work, has previously pioneered the development of brain-machine interfaces that could allow amputees and paralysed people to directly control prosthetic limbs and exoskeletons. His latest advance may have clinical benefits in brain rehabilitation, he predicts, but could also pave the way for “organic computers” - collectives of animal brains linked together to solve problems.
“Essentially we created a super-brain,” he said. “A collective brain created from three monkey brains. Nobody has ever done that before.”
He dismissed comparisons with science fiction plots, however, saying: “We’re conditioned by movies and Hollywood to think that everything related to science is dangerous and scary. These scary scenarios never crossed my mind and I’m the one doing the experiments.”
Anders Sandberg, a neuroethics researcher at the University of Oxford, said the work was the most convincing demonstration yet that brains can be linked together in direct communication. “People have claimed digital telepathy in various cool demos, but it’s mostly been total hype,” he said. “I’m quite impressed by this. It has a high ‘gosh’ factor.”
In the first study, scientists fitted three rhesus macaque monkeys with arrays that could record electrical activity from hundreds of neurons in the motor region of the brain.
The monkeys learnt, independently, to control the 3D movements of an avatar arm shown on a digital display in front of them, just by imagining moving it. The monkeys were then given joint control of the arm, with each monkey able to control two out of three dimensions (for instance, along the x- and y-axis) and their activity made a 50% contribution to each.
Although their brains were not directly wired together, the monkeys intuitively started to synchronise their brain activity, allowing them to move the arm collaboratively to a reach for a virtual ball on the screen.
The system appeared to work, even if one of the three monkeys was temporarily distracted. “Even if one monkey dropped out in one trial, the brain net is resilient,” said Nicolelis. “Imagine if you had, not three, but a million. That would be extremely resilient.”
In a second paper, also published in the journal Scientific Reports, the scientists directly linked the brains of rats together via two-way electrical connections that allowed the scientists to both deliver stimulus to neurons and read out electrical activity.
In one experiment, an electrical impulse was delivered to the brain of one rat, and the other rats learnt to synchronise their brain activity, mimicking the first rat’s brain response. In a sense, they were experiencing what the first rat felt, second-hand.
In another demonstration, pulses of stimulation that increased or decreased were delivered to the brains of individual rats, representing temperature and barometric pressure information. The rats were able to combine the information to produce a collective output that predicted an increased or decreased chance of rain. Rats scored better on this task when they were linked as a “brain net”, than when individual rats tried to combine the two pieces of initial information – temperature and pressure – to perform the simple calculation alone.
The scientists said that in the future, the concept might be extended to produce neurally connected “swarms” of rats with collective intelligence.
Nicolelis said that in the long-term the work could have “tremendous benefits” for brain rehabilitation. After suffering a stroke, for instance, language abilities might be able to be restored more quickly if a patient’s brain was retrained by directly synchronising with the language regions of the brain of a healthy person. In humans, the link could potentially be made non-invasively using electrodes on the scalp, however.
But he added it was unlikely that humans would ever be able to directly share complex mental experiences. “You’re not going to share your emotions or personality to a brain-net,” he said. “These are not reducible to a digital algorithm. You can’t reproduce these individual human attributes.”
Ultimately, people may also decide that wiring themselves up with others is not entirely desirable. “There may be special instances where you’d want a long-term connection with someone – like a married couple or a military platoon,” said Sandberg. “But there’s no guarantee that brain-to-brain interfaces will be a sensible thing in practice. There’s something to be said for neural privacy.”
http://www.theguardian.co(...)ain-connection#img-1
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
LARGE HADRON COLLIDER SCIENTISTS DISCOVER NEW PARTICLES: PENTAQUARKS
Although long believed to be theoretically possible, new data from Cern has provided conclusive evidence for a new state of matter
The Large Hadron Collider, which was switched on again earlier this year, will give researchers a chance to study the new particles on more detail and look for other types of pentaquark. Photograph: Peter Macdiarmid/Getty
Scientists at the Large Hadron Collider near Geneva have discovered a previously unseen class of particles that demonstrate there is a new state of matter.
Researchers working on the collider’s LHCb detector spotted signals that are produced when five subatomic particles called quarks combine together to form pentaquarks.
“It is an important result,” said Sheldon Stone, professor of physics at Syracuse University in New York. “It shows that there is a new state of matter. Although pentaquark states were thought possible from the dawn of the quark model, the theory that explains the structure of baryons like the proton, they had never been seen before.”
The discovery was made from data collected before the Large Hadron Collider switched on again earlier this year after a planned upgrade which allowed it to run at higher energy.
Scientists’ understanding of the structure of matter was transformed in 1964 when the American physicist Murray Gell-Mann proposed that protons and neutrons were made up of three new types of particles called quarks. The work earned him the Nobel prize in 1969.
Researchers on the LHCb team found evidence for pentaquarks after studying the disintegration of an unstable ball of three quarks called a Lambda baryon. The exotic pentaquarks they observed are made up of two up quarks, one down quark, one charm quark and one anti-charm quark. Details of the finding are reported today and have been submitted to the journal Physical Review Letters.
Guy Wilkinson, LHCb spokesperson, said the discovery confirms a prediction made by Gell-Mann more than half a century ago. “It’s been a big big puzzle,” he said.
“One place where pentaquarks may be relevant is when stars collapse and form neutron stars, the final stage of collapse before some go on to make black holes.
“In that environment, it’s quite possible that pentaquarks are formed, and if that’s so, it could have significant consequences for what happens to the stars, what they look like and what is their ultimate fate.”
Running at a higher energy than ever, the Large Hadron Collider will give researchers a chance to study the particles in more detail, and to look for other varieties of pentaquark. “Having found one, it’s highly likely there are others out there,” said Wilkinson.
http://www.theguardian.co(...)articles-pentaquarks
Although long believed to be theoretically possible, new data from Cern has provided conclusive evidence for a new state of matter
The Large Hadron Collider, which was switched on again earlier this year, will give researchers a chance to study the new particles on more detail and look for other types of pentaquark. Photograph: Peter Macdiarmid/Getty
Scientists at the Large Hadron Collider near Geneva have discovered a previously unseen class of particles that demonstrate there is a new state of matter.
Researchers working on the collider’s LHCb detector spotted signals that are produced when five subatomic particles called quarks combine together to form pentaquarks.
“It is an important result,” said Sheldon Stone, professor of physics at Syracuse University in New York. “It shows that there is a new state of matter. Although pentaquark states were thought possible from the dawn of the quark model, the theory that explains the structure of baryons like the proton, they had never been seen before.”
The discovery was made from data collected before the Large Hadron Collider switched on again earlier this year after a planned upgrade which allowed it to run at higher energy.
Scientists’ understanding of the structure of matter was transformed in 1964 when the American physicist Murray Gell-Mann proposed that protons and neutrons were made up of three new types of particles called quarks. The work earned him the Nobel prize in 1969.
Researchers on the LHCb team found evidence for pentaquarks after studying the disintegration of an unstable ball of three quarks called a Lambda baryon. The exotic pentaquarks they observed are made up of two up quarks, one down quark, one charm quark and one anti-charm quark. Details of the finding are reported today and have been submitted to the journal Physical Review Letters.
Guy Wilkinson, LHCb spokesperson, said the discovery confirms a prediction made by Gell-Mann more than half a century ago. “It’s been a big big puzzle,” he said.
“One place where pentaquarks may be relevant is when stars collapse and form neutron stars, the final stage of collapse before some go on to make black holes.
“In that environment, it’s quite possible that pentaquarks are formed, and if that’s so, it could have significant consequences for what happens to the stars, what they look like and what is their ultimate fate.”
Running at a higher energy than ever, the Large Hadron Collider will give researchers a chance to study the particles in more detail, and to look for other varieties of pentaquark. “Having found one, it’s highly likely there are others out there,” said Wilkinson.
http://www.theguardian.co(...)articles-pentaquarks
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
W&T / De LHC deel 3: Collision day...quote:Op dinsdag 14 juli 2015 22:58 schreef Kijkertje het volgende:
LARGE HADRON COLLIDER SCIENTISTS DISCOVER NEW PARTICLES: PENTAQUARKS
Although long believed to be theoretically possible, new data from Cern has provided conclusive evidence for a new state of matter
[ afbeelding ]
The Large Hadron Collider, which was switched on again earlier this year, will give researchers a chance to study the new particles on more detail and look for other types of pentaquark. Photograph: Peter Macdiarmid/Getty
Scientists at the Large Hadron Collider near Geneva have discovered a previously unseen class of particles that demonstrate there is a new state of matter.
Researchers working on the collider’s LHCb detector spotted signals that are produced when five subatomic particles called quarks combine together to form pentaquarks.
“It is an important result,” said Sheldon Stone, professor of physics at Syracuse University in New York. “It shows that there is a new state of matter. Although pentaquark states were thought possible from the dawn of the quark model, the theory that explains the structure of baryons like the proton, they had never been seen before.”
The discovery was made from data collected before the Large Hadron Collider switched on again earlier this year after a planned upgrade which allowed it to run at higher energy.
Scientists’ understanding of the structure of matter was transformed in 1964 when the American physicist Murray Gell-Mann proposed that protons and neutrons were made up of three new types of particles called quarks. The work earned him the Nobel prize in 1969.
Researchers on the LHCb team found evidence for pentaquarks after studying the disintegration of an unstable ball of three quarks called a Lambda baryon. The exotic pentaquarks they observed are made up of two up quarks, one down quark, one charm quark and one anti-charm quark. Details of the finding are reported today and have been submitted to the journal Physical Review Letters.
Guy Wilkinson, LHCb spokesperson, said the discovery confirms a prediction made by Gell-Mann more than half a century ago. “It’s been a big big puzzle,” he said.
“One place where pentaquarks may be relevant is when stars collapse and form neutron stars, the final stage of collapse before some go on to make black holes.
“In that environment, it’s quite possible that pentaquarks are formed, and if that’s so, it could have significant consequences for what happens to the stars, what they look like and what is their ultimate fate.”
Running at a higher energy than ever, the Large Hadron Collider will give researchers a chance to study the particles in more detail, and to look for other varieties of pentaquark. “Having found one, it’s highly likely there are others out there,” said Wilkinson.
http://www.theguardian.co(...)articles-pentaquarks
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
GHOSTLY PARTICLE WITH NO MASS FINALLY CREATED IN THE LAB
by Tia Ghose, Senior Writer | July 16, 2015
A 2015 study created a long-sought particle in a crystal of tantalum-arsenide. A detector image (top) shows the telltale sign of Weyl fermions, with the plus and minus signs denoting fermions of opposite chirality or handedness. The bottom schematic shows that even Weyl fermions with opposite charge-like characteristics can still move independently of one another, making them more mobile than other charged particles.
Credit: Su-Yang Xu and M. Zahid Hasan
A long-sought particle with no mass proposed more than 85 years ago has finally been created in the lab.
The mysterious particle, called a Weyl fermion, emerged from a crystal of a material called a semi-metal. By bombarding the crystal with photons, the team produced a stream of electrons that collectively behaved like the elusive subatomic particles.
The new discovery not only sheds light on the behavior of one of the most elusive fundamental particles, it could pave the way for ultra-low-power electronics, said study co-author Su-Yang Xu, a physicist at Princeton University in New Jersey.
Long-sought particle
Mathematician Hermann Weyl first proposed the mysterious massless particle in 1929. The particles would have a spin, but would also have "chirality," meaning they would spin as they traveled through space in either a left- or right-handed orientation, Xu said. When a left- and right-handed Weyl fermion come into contact, they would annihilate each other.
According to the Standard Model, the reigning model that describes subatomic particles, two major types of particles exist: Bosons and fermions. Bosons carry force and fermions are the teensy constituents of matter. However, scientists have long thought that fermions came in three types: Dirac, Majorana and Weyl. So far, scientists have found evidence in particle accelerators of the first two, but no hint of the latter.
However, in a 2011 study in the journal Physical Review B, researchers proposed that a crystal lattice with certain properties could produce Weyl fermions under the right conditions. In order to produce the ghostly particles, the material would need a certain kind of asymmetry, and would also have to be a semi-metal, a material with properties between an insulator and a conductor. The catch was that nobody knew exactly which materials to try.
So Xu and his colleagues pored over a database containing nearly 1 million descriptions of crystal lattices. They decided that a lattice made up of tantalum and arsenic would be a promising place to look. So they bombarded a tantalum-arsenide lattice with a beam of photons (particles of light), which energize electrons in the material. The extra bump of energy provided by the photons kicked the electrons out of their normal positions in the lattice and sent them moving. By detecting these displaced electrons, the team could understand how they were moving through the lattice.
By analyzing those properties, the team found that the electrons were acting very strangely. "The electron quasi-particle behaves exactly like a Weyl fermion," Xu said.
Better than superconductor
The new find could pave the way for better electronics. Weyl fermions are very stable, and, just like light, will stay at the same speed on the same course unless they annihilate with other Weyl fermions of the opposite chirality. As a result, they can travel for long distances and carry a charge without getting scattered inside the crystal lattice and generating heat, as normal electrons do, Xu said.
That means the new material could theoretically carry current better than existing materials used in electronics, Xu said.
And unlike superconductors, which only work when bathed in ultra-cold liquid helium or nitrogen, the new material could operate at room temperatures, Xu added.
In addition, one of the quirks of Weyl fermions is that on the quantum scale, when they experience an electric or magnetic field, they can switch their chirality, Xu said.
That means they have a strange "teleportation" ability, meaning they can spontaneously switch from a left- to right-handed flavor, in essence transporting a fermion of one flavor to a different location, said Leon Balents, a physicist at the Kavli Institute for Theoretical Physics at the University of California Santa Barbara, who was not involved in the study.
But the new finding, though fascinating, doesn't make the odds any better that a Weyl fermion could be found at an atom smasher like the Large Hadron Collider, said Ashvin Vishwanath, a theoretical condensed matter physicist at the University of California at Berkeley, who authored the 2011 study first proposing the existence of Weyl semi-metals.
"This sheds no light whatsoever on whether there are Weyl fermions in terms of fundamental particles," Vishwanath, who was not involved in the current study, told Live Science.
Either way, creating analogies to the fundamental particles in crystals could reveal new insights into how those particles would behave in the real world, he added.
"It's certainly giving a deeper understanding of some of these ideas in particle physics because you have to think about them in a new context," Vishwanath said.
http://www.livescience.com/51584-weyl-fermions-created-lab.html
by Tia Ghose, Senior Writer | July 16, 2015
A 2015 study created a long-sought particle in a crystal of tantalum-arsenide. A detector image (top) shows the telltale sign of Weyl fermions, with the plus and minus signs denoting fermions of opposite chirality or handedness. The bottom schematic shows that even Weyl fermions with opposite charge-like characteristics can still move independently of one another, making them more mobile than other charged particles.
Credit: Su-Yang Xu and M. Zahid Hasan
A long-sought particle with no mass proposed more than 85 years ago has finally been created in the lab.
The mysterious particle, called a Weyl fermion, emerged from a crystal of a material called a semi-metal. By bombarding the crystal with photons, the team produced a stream of electrons that collectively behaved like the elusive subatomic particles.
The new discovery not only sheds light on the behavior of one of the most elusive fundamental particles, it could pave the way for ultra-low-power electronics, said study co-author Su-Yang Xu, a physicist at Princeton University in New Jersey.
Long-sought particle
Mathematician Hermann Weyl first proposed the mysterious massless particle in 1929. The particles would have a spin, but would also have "chirality," meaning they would spin as they traveled through space in either a left- or right-handed orientation, Xu said. When a left- and right-handed Weyl fermion come into contact, they would annihilate each other.
According to the Standard Model, the reigning model that describes subatomic particles, two major types of particles exist: Bosons and fermions. Bosons carry force and fermions are the teensy constituents of matter. However, scientists have long thought that fermions came in three types: Dirac, Majorana and Weyl. So far, scientists have found evidence in particle accelerators of the first two, but no hint of the latter.
However, in a 2011 study in the journal Physical Review B, researchers proposed that a crystal lattice with certain properties could produce Weyl fermions under the right conditions. In order to produce the ghostly particles, the material would need a certain kind of asymmetry, and would also have to be a semi-metal, a material with properties between an insulator and a conductor. The catch was that nobody knew exactly which materials to try.
So Xu and his colleagues pored over a database containing nearly 1 million descriptions of crystal lattices. They decided that a lattice made up of tantalum and arsenic would be a promising place to look. So they bombarded a tantalum-arsenide lattice with a beam of photons (particles of light), which energize electrons in the material. The extra bump of energy provided by the photons kicked the electrons out of their normal positions in the lattice and sent them moving. By detecting these displaced electrons, the team could understand how they were moving through the lattice.
By analyzing those properties, the team found that the electrons were acting very strangely. "The electron quasi-particle behaves exactly like a Weyl fermion," Xu said.
Better than superconductor
The new find could pave the way for better electronics. Weyl fermions are very stable, and, just like light, will stay at the same speed on the same course unless they annihilate with other Weyl fermions of the opposite chirality. As a result, they can travel for long distances and carry a charge without getting scattered inside the crystal lattice and generating heat, as normal electrons do, Xu said.
That means the new material could theoretically carry current better than existing materials used in electronics, Xu said.
And unlike superconductors, which only work when bathed in ultra-cold liquid helium or nitrogen, the new material could operate at room temperatures, Xu added.
In addition, one of the quirks of Weyl fermions is that on the quantum scale, when they experience an electric or magnetic field, they can switch their chirality, Xu said.
That means they have a strange "teleportation" ability, meaning they can spontaneously switch from a left- to right-handed flavor, in essence transporting a fermion of one flavor to a different location, said Leon Balents, a physicist at the Kavli Institute for Theoretical Physics at the University of California Santa Barbara, who was not involved in the study.
But the new finding, though fascinating, doesn't make the odds any better that a Weyl fermion could be found at an atom smasher like the Large Hadron Collider, said Ashvin Vishwanath, a theoretical condensed matter physicist at the University of California at Berkeley, who authored the 2011 study first proposing the existence of Weyl semi-metals.
"This sheds no light whatsoever on whether there are Weyl fermions in terms of fundamental particles," Vishwanath, who was not involved in the current study, told Live Science.
Either way, creating analogies to the fundamental particles in crystals could reveal new insights into how those particles would behave in the real world, he added.
"It's certainly giving a deeper understanding of some of these ideas in particle physics because you have to think about them in a new context," Vishwanath said.
http://www.livescience.com/51584-weyl-fermions-created-lab.html
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
HEAVY METAL UPGRADE TO DETECT ANTIMATTER
Ben Still describes new plans to upgrade a huge tank of water surrounded by light detectors, so that it can detect antineutrinos
Inside the huge neutrino detector Photograph: Kamioka Observatory, ICRR/University of Tokyo
Heavy metal is being added to one of the worlds largest particle physics experiments to allow it to see antimatter for the first time¹. For years the Super Kamiokande neutrino observatory has been a world leader in the field of neutrino particle physics. Last week the international collaboration of scientists who run the experiment announced that in 2016/2017, for the first time in over a decade, the experiments ultra sensitive detector will be shut down for an upgrade.
A common view among physicists is that a key piece of our Universe’s Big Bang creation story is locked up in our understanding of the tiny differences in behaviour of neutrinos and their antimatter version - antineutrinos. The upgraded Super Kamiokande detector will be able to distinguish between the interactions of these two particles inside the detector - something it has been incapable of until now. Because the experiment has been the largest and most successful neutrino experiment to date it is expected that we will soon be close to filling in the missing piece of the creation story puzzle.
Super-Kamiokande (Super-K)
Since construction completed in 1998 1996 Super-K has opened its doors just twice for upgrades and repairs, last time in 2006. It is one of the most beautiful man made structures on this planet.
Super-K detects neutrino particles via their interaction with water. Too small to interact directly with the water molecules, neutrinos interact with neutrons in the nucleus of the Hydrogen and Oxygen atoms from which water is made. The interaction of neutrino and neutron produces a proton and a second charged particle. The second charged particle that is produced depends upon the type of neutrino interacting: an electron-neutrino produces and electron; a muon-neutrino produces a Muon (which is simply a heavier version of an electron).
νe + n → e- + p
(electron-neutrino + neutron → electron + proton)
νμ + n → μ- + p
(muon-neutrino + neutron → muon + proton)
The charged particle produced alongside the proton has enough energy that it is born travelling faster than the speed of light in water. You may have heard that nothing can travel faster than light, and this is true for light in empty space. But when light travels through water, glass, or indeed anything other than empty space, then the electrons in surrounding atoms slow the light down. Light travels through water at roughly 75% of the speed with which it travels through empty space. This means it is not against the laws of physics for a charged particle to travel faster than light within water. If this happens a blue light known as Cherenkov radiation is emitted. This Cherenkov radiation is picked up by almost 12,000 light sensitive detectors surrounding the water, which turn it into electrical signal to be interpreted by computers.
Cherenkov radiation from an electron in Super-K Photograph: Super-K/Super-K
If an antineutrino interacts it interacts with a proton in the nucleus of Hydrogen or Oxygen atoms. In this interaction a neutron and charged antiparticle are produced. The antiparticle that is produced again depends upon the antineutrino interacting: an electron-antineutrino produces an anti-electron (positron); a muon-antineutrino produces a anti-muon (which is simply a heavier version of an positron). While these antiparticles have a different sign electric charge to their mirror particle cousins, they still create Cherenkov radiation in exactly the same way because the size of the charge (and their mass) is the same. Super-K can therefore not distinguish if it is particles of antiparticles producing the Cherenkov radiation. This leads then to Super-K scientists not being able to tell if it was a neutrino or antineutrino interaction they witnessed.
anti-νe + p → e+ + p
(electron-antineutrino + proton → positron + neutron)
anti-νμ + p → μ+ + p
(muon-antineutrino + proton → antimuon + neutron)
Cherenkov radiation from a muon seen by Super-K Photograph: Super-K/Super-K
Gadolinium
The addition of Gadolinium, by dissolving small amounts of Gadolinium salts, changes the game plan. Gadolinium is great at capturing neutrons, sucking them right into its nucleus. Just as a ball rolling to the bottom of a hill loses gravitational energy, a neutron falling into, and being captured by, a nucleus also loses energy. The ball transfers gravitational energy into movement (kinetic energy); a captured neutron gives all of its energy to the nucleus it is captured by. The now excited nucleus need to lose energy and does this by emitting light.
The speed of a ball at the bottom of a hill depends on the height of the hill. The amount of energy given to the nucleus by the neutron and then emitted as light when captured depends upon the atom it is captured by. Some atoms require neutrons to lose more energy than others; each atom has a unique energy of light emitted during neutron capture. If neutrons are captured only by Gadolinium atoms then the light they emit will be at a definite and singular energy.
A neutron falls into a gadolinium nucleus, and excites it. Photograph: Ben Still/Ben Still
The tiny quantities of Gadolinium does not effect the production of Cherenkov radiation, so just looking at this we would be in the same situation. What the Gadolinium does allow us to do, however, is to know when a neutron was produced. If the upgraded Super-K sees Cherenkov light followed by additional light of the right energy then we can say with confidence that a neutron was produced in that interaction. As it is only the antineutrino interaction that produces a neutron then we now have a way of distinguishing if the preceding Cherenkov light came from an interaction of a neutrino or antineutrino.
Imbalance and Creation
Neutrinos and antineutrinos display strange behaviour where they can change from one type to another over a journey of kilometres. This change is known as oscillation and it is a field of research where Super-K has found the most success. Just last year, as an integral part of the T2K experiment, it helped detect the last predicted oscillation from a muon-neutrino to electron-neutrino.
Neutrino detectors are in the midst of a change of form from discovery to precision measurement machines. The next generation of experiment will be probing the difference between the way in which neutrinos and antineutrinos oscillate. The difference they hope to find is essential to scientific understanding of the creation of our Universe. If Nature were perfectly balanced then nothing of ‘solid’ substance would exist; equal amount of matter and antimatter would have annihilate one another and our universe could only be filled with light. At some level in the laws of nature matter and antimatter behave differently, if they did not then we would not be here. Efforts of researchers in this field of science continues toward discovery by uncovering the secrets of the most secretive neutrino, in this is the beginning of a new era.
http://www.theguardian.co(...)ect-antimatter#img-1
[ Bericht 0% gewijzigd door Kijkertje op 21-07-2015 14:09:46 ]
Ben Still describes new plans to upgrade a huge tank of water surrounded by light detectors, so that it can detect antineutrinos
Inside the huge neutrino detector Photograph: Kamioka Observatory, ICRR/University of Tokyo
Heavy metal is being added to one of the worlds largest particle physics experiments to allow it to see antimatter for the first time¹. For years the Super Kamiokande neutrino observatory has been a world leader in the field of neutrino particle physics. Last week the international collaboration of scientists who run the experiment announced that in 2016/2017, for the first time in over a decade, the experiments ultra sensitive detector will be shut down for an upgrade.
A common view among physicists is that a key piece of our Universe’s Big Bang creation story is locked up in our understanding of the tiny differences in behaviour of neutrinos and their antimatter version - antineutrinos. The upgraded Super Kamiokande detector will be able to distinguish between the interactions of these two particles inside the detector - something it has been incapable of until now. Because the experiment has been the largest and most successful neutrino experiment to date it is expected that we will soon be close to filling in the missing piece of the creation story puzzle.
Super-Kamiokande (Super-K)
Since construction completed in 1998 1996 Super-K has opened its doors just twice for upgrades and repairs, last time in 2006. It is one of the most beautiful man made structures on this planet.
Super-K detects neutrino particles via their interaction with water. Too small to interact directly with the water molecules, neutrinos interact with neutrons in the nucleus of the Hydrogen and Oxygen atoms from which water is made. The interaction of neutrino and neutron produces a proton and a second charged particle. The second charged particle that is produced depends upon the type of neutrino interacting: an electron-neutrino produces and electron; a muon-neutrino produces a Muon (which is simply a heavier version of an electron).
νe + n → e- + p
(electron-neutrino + neutron → electron + proton)
νμ + n → μ- + p
(muon-neutrino + neutron → muon + proton)
The charged particle produced alongside the proton has enough energy that it is born travelling faster than the speed of light in water. You may have heard that nothing can travel faster than light, and this is true for light in empty space. But when light travels through water, glass, or indeed anything other than empty space, then the electrons in surrounding atoms slow the light down. Light travels through water at roughly 75% of the speed with which it travels through empty space. This means it is not against the laws of physics for a charged particle to travel faster than light within water. If this happens a blue light known as Cherenkov radiation is emitted. This Cherenkov radiation is picked up by almost 12,000 light sensitive detectors surrounding the water, which turn it into electrical signal to be interpreted by computers.
Cherenkov radiation from an electron in Super-K Photograph: Super-K/Super-K
If an antineutrino interacts it interacts with a proton in the nucleus of Hydrogen or Oxygen atoms. In this interaction a neutron and charged antiparticle are produced. The antiparticle that is produced again depends upon the antineutrino interacting: an electron-antineutrino produces an anti-electron (positron); a muon-antineutrino produces a anti-muon (which is simply a heavier version of an positron). While these antiparticles have a different sign electric charge to their mirror particle cousins, they still create Cherenkov radiation in exactly the same way because the size of the charge (and their mass) is the same. Super-K can therefore not distinguish if it is particles of antiparticles producing the Cherenkov radiation. This leads then to Super-K scientists not being able to tell if it was a neutrino or antineutrino interaction they witnessed.
anti-νe + p → e+ + p
(electron-antineutrino + proton → positron + neutron)
anti-νμ + p → μ+ + p
(muon-antineutrino + proton → antimuon + neutron)
Cherenkov radiation from a muon seen by Super-K Photograph: Super-K/Super-K
Gadolinium
The addition of Gadolinium, by dissolving small amounts of Gadolinium salts, changes the game plan. Gadolinium is great at capturing neutrons, sucking them right into its nucleus. Just as a ball rolling to the bottom of a hill loses gravitational energy, a neutron falling into, and being captured by, a nucleus also loses energy. The ball transfers gravitational energy into movement (kinetic energy); a captured neutron gives all of its energy to the nucleus it is captured by. The now excited nucleus need to lose energy and does this by emitting light.
The speed of a ball at the bottom of a hill depends on the height of the hill. The amount of energy given to the nucleus by the neutron and then emitted as light when captured depends upon the atom it is captured by. Some atoms require neutrons to lose more energy than others; each atom has a unique energy of light emitted during neutron capture. If neutrons are captured only by Gadolinium atoms then the light they emit will be at a definite and singular energy.
A neutron falls into a gadolinium nucleus, and excites it. Photograph: Ben Still/Ben Still
The tiny quantities of Gadolinium does not effect the production of Cherenkov radiation, so just looking at this we would be in the same situation. What the Gadolinium does allow us to do, however, is to know when a neutron was produced. If the upgraded Super-K sees Cherenkov light followed by additional light of the right energy then we can say with confidence that a neutron was produced in that interaction. As it is only the antineutrino interaction that produces a neutron then we now have a way of distinguishing if the preceding Cherenkov light came from an interaction of a neutrino or antineutrino.
Imbalance and Creation
Neutrinos and antineutrinos display strange behaviour where they can change from one type to another over a journey of kilometres. This change is known as oscillation and it is a field of research where Super-K has found the most success. Just last year, as an integral part of the T2K experiment, it helped detect the last predicted oscillation from a muon-neutrino to electron-neutrino.
Neutrino detectors are in the midst of a change of form from discovery to precision measurement machines. The next generation of experiment will be probing the difference between the way in which neutrinos and antineutrinos oscillate. The difference they hope to find is essential to scientific understanding of the creation of our Universe. If Nature were perfectly balanced then nothing of ‘solid’ substance would exist; equal amount of matter and antimatter would have annihilate one another and our universe could only be filled with light. At some level in the laws of nature matter and antimatter behave differently, if they did not then we would not be here. Efforts of researchers in this field of science continues toward discovery by uncovering the secrets of the most secretive neutrino, in this is the beginning of a new era.
http://www.theguardian.co(...)ect-antimatter#img-1
[ Bericht 0% gewijzigd door Kijkertje op 21-07-2015 14:09:46 ]
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
AT THE LIMIT OF MOORE'S LAW: SCIENTISTS DEVELOP MOLECULE-SIZED TRANSISTORS
Researchers find transistors can be produced consisting of atoms 600,000 times thinner than a human hair – paving way for atom-scale chips
A strand of DNA is 15 times larger than indium atoms which make up the transistor. Photograph: Mopic/Alamy
Scientists have created a transistor made up of a single molecule. Surrounded by just 12 atoms, it is likely to be the smallest possible size for a transistor – and the hard limit for Moore’s law.
The transistor is made of a single molecule of phthalocyanine surrounded by ring of 12 positively charged indium atoms placed on an indium arsenide crystal, as revealed in the scientific journal Nature Physics.
Each indium atom is 167 picometres in diameter, which makes them 0.167nm wide or 42 times smaller than the very smallest circuits currently possible, as recently revealed by IBM.
For comparison a strand of human hair, at 100,000nm thick, is about 600,000 times wider than the atoms surrounding the new transistor. A red blood cell is a 36,000 times bigger, at 6,000nm in diameter. Even a strand of DNA is 15 times bigger at 2.5nm wide.
Phthalocyanine molecule in centre of transistor is surrounded by 12 positively charged indium atoms. Photograph: US Naval Research Laboratory
The transistor represents a big step forward toward quantum computing, and was made possible using a scanning tunnelling electron microscope to place atoms in exact positions and control the electron flow through the gate.
Typically scientists working to this atomic scale have struggled to reliably control the flow of electrons, which are difficult to contain and can jump outside of the transistor, rendering it useless.
The international team of researchers from Paul-Drude-Institut für Festkörperelektronik and the Freie Universität Berlin, Germany, the NTT Basic Research Laboratories, Japan, and the US Naval Research Laboratory also discovered unexpected behaviour from the transistor. The orientation of the molecule of phthalocyanine – an organic molecule typically used in dyes – at the heart of the transistor is affected by charge.
A red blood cell is around 6,000nm in diameter, meaning around 7,200 of the new transistors could fit on a single cell. Photograph: Ikon Images/Rex Shutterstock
Its orientation could be changed by altering its charge, leading to more than a simple on-off switch-like state as seen in traditional transistors.
The work proves that precise control of atoms to create a transistor smaller than any other quantum system available is possible and opens the door to further research into harnessing these tiny transistors for computers and systems with orders of magnitude more processing power than today’s machines.
Chip manufacturers have struggled to maintain Moore’s law, which dictates that processing power will double every 18 to 24 months, primarily through the doubling of the number of transistors they can fit on a chip. The more transistors that can fit on a chip, the more powerful it can be.
Chips used in computers are currently made at the 14nm scale, but going smaller has proven difficult, with 7nm the latest breakthrough. While single-molecule transistors are nowhere near being ready to put into a chip, this new research will help bring about quantum computing, widely considered to be the next stage in the evolution of computers.
http://www.theguardian.co(...)rs-atoms-chips#img-1
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
Image: Andrew Pontzen, University College London
NEW MODEL SUGGESTS NEW MODEL ACTS UNCANNILY LIKE PARTICLES FOUND IN THE 1930S
We might be looking for dark matter in all the wrong places.
According to new study, dark matter may not be as exotic as we’ve been led to believe. In fact, it may act remarkably similar to ‘pions’ - subatomic particles that were discovered back in the 1930s - and knowing this may finally help us detect the mysterious matter, which accounts for 85 percent of the Universe’s mass.
Despite the fact that dark matter is predicted to be pretty much everywhere, scientists have never been able to directly observe it. This is because it’s long been assumed to not interact with anything other than gravity, allowing it to travel through the Universe unnoticed, effectively in its own dimension - hence the name ‘dark’. But a team of physicists led by the University of Tokyo in Japan has come up with a new hypothesis that suggests this might not be the case.
"We have seen this kind of particle before," one of the lead researchers, Hitoshi Murayama, said in a press release. "It has the same properties - same type of mass, the same type of interactions, in the same type of theory of strong interactions that gave forth the ordinary pions."
Put simply, their model suggests that dark matter does actually interact with something - itself. And if it’s doing this within galaxies and galaxy clusters, it changes the predicted mass distributions of dark matter, and could explain why we haven’t been able to detect it yet.
"It can resolve outstanding discrepancies between data and computer simulations," said on of the team, Eric Kuflik, a physicist from Cornell University in the US.
This isn’t the first time that scientists have suggested that dark matter may not be so ‘dark’. The hypothesis is backed up by a study that came out in April, which provided the first ever evidence that dark matter was interacting with itself. But the new model will help us figure out how the elusive particles could be detected in future, and how to recognise them if we do.
"The key differences in these properties between this new class of dark matter theories and previous ideas have profound implications on how dark matter can be discovered in upcoming experimental searches," said Yonit Hotchberg, a team member from the University of California, Berkeley.
Take for example the artist’s impression below of dark matter distribution (white) within a galaxy. The image on the left shows all the dark matter condensed in the centre of the galaxy, as is predicted by traditional models, while the image on the right shows dark matter distributed throughout the galaxy, due to its interactions with itself:
Kavli IPMU & NASA/STScI
The next step is to put the predictions from the model to the test using real experiments, such as the Large Hadron Collider, Japan's SuperKEKB electron-positron collider, or the proposed Search for Hidden Particles (SHiP) experiment at CERN.
Understanding exactly how dark matter works is so important to scientists, because it's key to understanding how the Universe came to be - dark matter is crucial in forming not only galaxies, stars and solar systems, but also keeping our own bodies intact.
"It is incredibly exciting that we may finally understand why we came to exist," said Murayama. We couldn’t agree more.
http://www.sciencealert.c(...)s-found-in-the-1930s
Image: Andrew Pontzen, University College London NEW MODEL SUGGESTS NEW MODEL ACTS UNCANNILY LIKE PARTICLES FOUND IN THE 1930S
We might be looking for dark matter in all the wrong places.
According to new study, dark matter may not be as exotic as we’ve been led to believe. In fact, it may act remarkably similar to ‘pions’ - subatomic particles that were discovered back in the 1930s - and knowing this may finally help us detect the mysterious matter, which accounts for 85 percent of the Universe’s mass.
Despite the fact that dark matter is predicted to be pretty much everywhere, scientists have never been able to directly observe it. This is because it’s long been assumed to not interact with anything other than gravity, allowing it to travel through the Universe unnoticed, effectively in its own dimension - hence the name ‘dark’. But a team of physicists led by the University of Tokyo in Japan has come up with a new hypothesis that suggests this might not be the case.
"We have seen this kind of particle before," one of the lead researchers, Hitoshi Murayama, said in a press release. "It has the same properties - same type of mass, the same type of interactions, in the same type of theory of strong interactions that gave forth the ordinary pions."
Put simply, their model suggests that dark matter does actually interact with something - itself. And if it’s doing this within galaxies and galaxy clusters, it changes the predicted mass distributions of dark matter, and could explain why we haven’t been able to detect it yet.
"It can resolve outstanding discrepancies between data and computer simulations," said on of the team, Eric Kuflik, a physicist from Cornell University in the US.
This isn’t the first time that scientists have suggested that dark matter may not be so ‘dark’. The hypothesis is backed up by a study that came out in April, which provided the first ever evidence that dark matter was interacting with itself. But the new model will help us figure out how the elusive particles could be detected in future, and how to recognise them if we do.
"The key differences in these properties between this new class of dark matter theories and previous ideas have profound implications on how dark matter can be discovered in upcoming experimental searches," said Yonit Hotchberg, a team member from the University of California, Berkeley.
Take for example the artist’s impression below of dark matter distribution (white) within a galaxy. The image on the left shows all the dark matter condensed in the centre of the galaxy, as is predicted by traditional models, while the image on the right shows dark matter distributed throughout the galaxy, due to its interactions with itself:
Kavli IPMU & NASA/STScI
The next step is to put the predictions from the model to the test using real experiments, such as the Large Hadron Collider, Japan's SuperKEKB electron-positron collider, or the proposed Search for Hidden Particles (SHiP) experiment at CERN.
Understanding exactly how dark matter works is so important to scientists, because it's key to understanding how the Universe came to be - dark matter is crucial in forming not only galaxies, stars and solar systems, but also keeping our own bodies intact.
"It is incredibly exciting that we may finally understand why we came to exist," said Murayama. We couldn’t agree more.
http://www.sciencealert.c(...)s-found-in-the-1930s
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
INDEPENDANT EXPERT CONFIRMS THAT THE "IMPOSSIBLE" EM DRIVE ACTUALLY WORKS
It's the propulsion system that just won't quit.
Over the past year, there's been a whole lot of excitement about the electromagnetic propulsion drive, or EM Drive - a scientifically impossible engine that's defied pretty much everyone's expectations by continuing to stand up to experimental scrutiny.
The drive is so exciting because it produces huge amounts of propulsion that could theoretically blast us to Mars in just 70 days, without the need for heavy and expensive rocket fuel. Instead, it's apparently propelled forward by microwaves bouncing back and forth inside an enclosed chamber, and this is what makes the drive so powerful, and at the same time so controversial.
As efficient as this type of propulsion may sound, it defies one of the fundamental concepts of physics - the conservation of momentum, which states that for something to be propelled forward, some kind of propellant needs to be pushed out in the opposite direction.
For that reason, the drive was widely laughed at and ignored when it was invented by English researcher Roger Shawyer in the early 2000s. But a few years later, a team of Chinese scientists decided to build their own version, and to everyone's surprise, it actually worked. Then an American inventor did the same, and convinced NASA's Eagleworks Laboratories, headed up by Harold 'Sonny' White, to test it.
The real excitement began when those Eagleworks researchers admitted back in March that, despite more than a year of trying to poke holes in the EM Drive, it just kept on working - even inside a vacuum. This debunked some of their most common theories about what might be causing the anomaly.
Now Martin Tajmar, a professor and chair for Space Systems at Dresden University of Technology in Germany, has played around with his own EM Drive, and has once again shown that it produces thrust - albeit for reasons he can't explain.
Tajmar presented his results at the 2015 American Institute for Aeronautics and Astronautics' Propulsion and Energy Forum and Exposition in Florida on 27 July, and you can read his paper here. He has a long history of experimentally testing (and debunking) breakthrough propulsion systems, so his results are a pretty big deal for those looking for outside verification of the EM Drive.
To top it off, his system produced a similar amount of thrust as was originally predicted by Shawyer, which is several thousand times greater than a standard photon rocket.
"Our test campaign cannot confirm or refute the claims of the EM Drive but intends to independently assess possible side-effects in the measurements [sic] methods used so far," Tajmar and graduate student Georg Fiedler write in their conference abstract. "Nevertheless, we do observe thrust close to the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena."
So where does all of this leave us with the EM Drive? While it's fun to speculate about just how revolutionary it could be for humanity, what we really need now are results published in a peer-reviewed journal - which is something that Shawyer claims he is just a few months away from doing, as David Hambling reports for Wired.
But even then, until we can figure out exactly how the EM Drive works, it's unlikely that the idea is going to be taken seriously by the scientific community. For now, all scientists can do is keep testing the system in a range of different environments and try to work out what's causing this "impossible" thrust.
It might turn out that we need to rewrite some of our laws of physics in order to explain how the drive works. But if that opens up the possibility of human travel throughout the Solar System - and, more importantly, beyond - then it's a sacrifice we're definitely willing to make. Bring on the next set of tests.
http://www.sciencealert.c(...)rive-produces-thrust
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
30-07-2015
Harvard-wetenschappers maken miniatuurlasers uit cellen
© thinkstock.
Wetenschap Wetenschappers zijn erin geslaagd cellen om te vormen tot miniatuurlasers. Dat schrijft het Amerikaanse nieuwsmedium Quartz.
Een laser kan tot stand komen door kleurstof in een gesloten, weerspiegelende omgeving aan te brengen en het licht vervolgens te weerkaatsen. Wat dan zichtbaar wordt is een geconcentreerde, monochromatische straal: laserlicht.
Een team van wetenschappers aan Harvard Medical School, onder leiding van Seok Hyun Yun en Matja¸ Humar, heeft gebruik gemaakt van datzelfde principe. Door levende cellen te vullen met kleurstof, slaagden ze erin om binnenin kleine lasers te construeren.
Hun methode zou gebruikt kunnen worden om individuele cellen, bijvoorbeeld kankercellen, te markeren en hun bewegingen doorheen het menselijk lichaam te volgen. Het team publiceerde een gedetailleerd verslag in het wetenschappelijke tijdschrift Nature Photonics.
Drie methoden
Yun en Humar gebruikten drie verschillende methoden om hun microlasers te creëren. Voor een eerste methode injecteerden ze olie in menselijke cellen en vulden ze de oliedruppeltjes met fluorescerende kleurstof. Wanneer ze de cellen vervolgens belichtten, produceerden de kleurstofatomen in de cellen een gefocuste lichtstraal.
Voor een tweede methode lieten de onderzoekers macrofagen - een specifiek type witte bloedcellen dat lichaamsvreemde deeltjes kan opnemen - met kleurstof gevulde polystyreenkorreltjes opeten. Ook zij zonden laserstralen uit toen ze beschenen werden met niet-laserlicht.
Voor de laatste methode gebruikten de wetenschappers vetcellen uit varkenshuid. Net zoals bij de twee vorige methoden werd kleurstof in de cellen geïnjecteerd. Ook hier produceerden de cellen een laserstraal wanneer ze beschenen werden doorheen onderhuids glasvezel. Licht projecteren op de huid was in dit geval niet voldoende, omdat de vetcellen onder het huidoppervlak zitten.
Toekomstig onderzoek
De ontdekking kan veel betekenen voor toekomstig onderzoek. Wetenschappers maken nu al gebruik van kleurstoffen om cellen te markeren, maar de huidige techniek laat niet toe om cellen duidelijk van elkaar te onderscheiden. Lasers werken veel nauwkeuriger, waardoor het voor onderzoekers theoretisch mogelijk wordt om elke cel een individuele lasermarkering te geven.
"De meest interessante toepassing is waarschijnlijk celmarkering", vertelt Humar in Quartz. Tot nu toe hebben de wetenschappers hun cellen alleen gemarkeerd in petrischaaltjes, maar volgens Humar is er geen enkele reden waarom de techniek niet zou werken in het menselijk lichaam. "In principe zou het mogelijk moeten zijn om elke individuele cel te markeren en te volgen doorheen het hele lichaam."
Ooit zouden de lasers zelfs kunnen helpen bepalen waarvan een kankercel gemaakt is, menen de wetenschappers. Dokters zouden dan niet langer een biopsie moeten uitvoeren - daarbij wordt een stukje weefsel uit het lichaam gehaald - maar zouden de inhoud van de cel kunnen analyseren met behulp van een laser.
(HLN)
Harvard-wetenschappers maken miniatuurlasers uit cellen
© thinkstock.
Wetenschap Wetenschappers zijn erin geslaagd cellen om te vormen tot miniatuurlasers. Dat schrijft het Amerikaanse nieuwsmedium Quartz.
Een laser kan tot stand komen door kleurstof in een gesloten, weerspiegelende omgeving aan te brengen en het licht vervolgens te weerkaatsen. Wat dan zichtbaar wordt is een geconcentreerde, monochromatische straal: laserlicht.
Een team van wetenschappers aan Harvard Medical School, onder leiding van Seok Hyun Yun en Matja¸ Humar, heeft gebruik gemaakt van datzelfde principe. Door levende cellen te vullen met kleurstof, slaagden ze erin om binnenin kleine lasers te construeren.
Hun methode zou gebruikt kunnen worden om individuele cellen, bijvoorbeeld kankercellen, te markeren en hun bewegingen doorheen het menselijk lichaam te volgen. Het team publiceerde een gedetailleerd verslag in het wetenschappelijke tijdschrift Nature Photonics.
Drie methoden
Yun en Humar gebruikten drie verschillende methoden om hun microlasers te creëren. Voor een eerste methode injecteerden ze olie in menselijke cellen en vulden ze de oliedruppeltjes met fluorescerende kleurstof. Wanneer ze de cellen vervolgens belichtten, produceerden de kleurstofatomen in de cellen een gefocuste lichtstraal.
Voor een tweede methode lieten de onderzoekers macrofagen - een specifiek type witte bloedcellen dat lichaamsvreemde deeltjes kan opnemen - met kleurstof gevulde polystyreenkorreltjes opeten. Ook zij zonden laserstralen uit toen ze beschenen werden met niet-laserlicht.
Voor de laatste methode gebruikten de wetenschappers vetcellen uit varkenshuid. Net zoals bij de twee vorige methoden werd kleurstof in de cellen geïnjecteerd. Ook hier produceerden de cellen een laserstraal wanneer ze beschenen werden doorheen onderhuids glasvezel. Licht projecteren op de huid was in dit geval niet voldoende, omdat de vetcellen onder het huidoppervlak zitten.
Toekomstig onderzoek
De ontdekking kan veel betekenen voor toekomstig onderzoek. Wetenschappers maken nu al gebruik van kleurstoffen om cellen te markeren, maar de huidige techniek laat niet toe om cellen duidelijk van elkaar te onderscheiden. Lasers werken veel nauwkeuriger, waardoor het voor onderzoekers theoretisch mogelijk wordt om elke cel een individuele lasermarkering te geven.
"De meest interessante toepassing is waarschijnlijk celmarkering", vertelt Humar in Quartz. Tot nu toe hebben de wetenschappers hun cellen alleen gemarkeerd in petrischaaltjes, maar volgens Humar is er geen enkele reden waarom de techniek niet zou werken in het menselijk lichaam. "In principe zou het mogelijk moeten zijn om elke individuele cel te markeren en te volgen doorheen het hele lichaam."
Ooit zouden de lasers zelfs kunnen helpen bepalen waarvan een kankercel gemaakt is, menen de wetenschappers. Dokters zouden dan niet langer een biopsie moeten uitvoeren - daarbij wordt een stukje weefsel uit het lichaam gehaald - maar zouden de inhoud van de cel kunnen analyseren met behulp van een laser.
(HLN)
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
Image: A representation of the evolution of the universe over 13.77 billion years. NASA / WMAP Science Team
DON'T PANIC, BUT THE UNIVERSE IS SLOWLY DYING
But as long as you know where your towel is, you should be fine.
We know that our Universe has already lived through great number of exciting phases. But new research released overnight shows the Universe has long passed its peak and is slowly but surely dying. The research was presented at the year’s largest gathering of astronomers at the International Astronomical Union’s General Assembly in Hawaii. But before we start writing any obituaries, let’s have a quick recap of the good times.
When the Universe was less than a second old and more than a billion degrees Celsius, it was hot enough for exotic particles to freely pop in and out of existence. As the Universe expanded, it cooled and was no longer able to produce hugely energetic particles. After a few seconds, the Universe was a sea of protons and neutrons, and after a few minutes it was mostly a dense fog of hydrogen and helium. In terms of building more complex matter, that was pretty much the end of the action for 400,000 years.
Then, quite suddenly, matter and radiation were decoupled and photons of light were able to free-stream across the Universe for the first time. This is all very exciting for cosmology, but something important had also happened to the hydrogen and helium: it could now hold onto electrons and create neutral atoms.
When the Universe was less than a second old and more than a billion degrees Celsius, it was hot enough for exotic particles to freely pop in and out of existence. As the Universe expanded, it cooled and was no longer able to produce hugely energetic particles. After a few seconds, the Universe was a sea of protons and neutrons, and after a few minutes it was mostly a dense fog of hydrogen and helium. In terms of building more complex matter, that was pretty much the end of the action for 400,000 years.
Then, quite suddenly, matter and radiation were decoupled and photons of light were able to free-stream across the Universe for the first time. This is all very exciting for cosmology, but something important had also happened to the hydrogen and helium: it could now hold onto electrons and create neutral atoms.
Early building blocks of life
This is another step on the path to making you and me: we need neutral hydrogen in order to form molecular hydrogen, we need this to efficiently cool pockets of gas that collapse rapidly to form the first stars, and we need stars to form the heavy elements such as carbon and oxygen that are the building blocks of life.
By this stage the Universe was a few hundred million years old, and it was now busy heating itself back up as these first stars irradiated the surrounding material. These stars were blowing themselves apart and dumping large quantities of heavy atomic species into space, producing many of the heavier elements we see today. Some of them may also have collapsed into black holes, sowing the seeds of some of the most massive galaxies that exist in the present day Universe.
After this early phase of forming the first stars, we began to see the first structures that resemble modern galaxies, but in a very messy and violent form. For the next few billion years galaxies smashed together to form more massive systems and star formation was rapidly turned on and off. This activity continued until the Universe was about 3 billion years old, a period we know as the peak of cosmic star formation. So the u=Universe got most of the exciting stuff out of the way really early on.
What has it been doing since then? It is slowly but steadily dying. It is still producing new stars every now and again, but the rate at which old stars are fading outstrips these bright young things.
A top down view of the major 3D redshift surveys of the local Universe with Earth at the centre. Each dot represents a single galaxy, and the direction shows their location on the sky. The distance from the centre shows the light travel time from Earth. Here we see the most recent 5 billion years of the Universe, which has taken thousands of nights of observing on some of the most massive telescopes to construct. ICRAR/GAMA
Enter the dark stuff
To exacerbate things even further, about 3 billion years ago a mysterious (and much studied) entity called dark energy began to dominate the energy contents of the Universe and accelerate everything apart (measuring this acceleration won Australian researcher Brian Schmidt and others a Nobel prize). The Universe had already started cooling off by this stage, so dark energy arriving on the scene really twisted the knife.
How do we know all of this? Well, we have been building the evidence for a while and careful models of galaxy evolution have already suggested that the Universe is fading, but we wanted to directly observe this effect over many billions of years.
In the past few years a large Australian led project called the Galaxy And Mass Assembly (GAMA) survey invested huge effort into measuring most of the energy output from stars. We had to observe nearby galaxies from the far-ultraviolet (where young stars produce much of their light) through the optical and the near-infrared (where most stars peak in energy output) all the way into the far-infrared (where star light absorbed by dust is re-emitted).
GAMA has been able to measure this huge span of radiation over the past 5 billion years for almost 200,000 galaxies, categorically establishing that the energy output of stars in the Universe is winding down.
A galaxy from the GAMA survey observed at different wavelengths from the far ultraviolet to the far infrared. The inset graph shows how much energy is being generated at different wavelengths. ICRAR/GAMA, CC BY-NC
The good news is that the stars made to date will still last many billions of years yet (including our own sun). Some of the smaller stars should keep shining for longer than the current age of the Universe. There are questions over what exactly the dominance of dark energy will mean in the long term, with some of more exotic theories speculating that it could tear everything apart in a 'Big Rip':
Less dramatic, and more likely given our current knowledge, is the theory that the Universe will continue to cool forever, and non gravitationally bound structures will steadily move apart from each other. After trillions of years we will only be able to see our own galaxy as the others will have raced too far away. After hundreds of trillions of years no new stars will be made anywhere at all.
Next our galaxy will eject most of its remaining stars into the cosmic void, and what is left will collapse into our central black hole. All matter as we know it will eventually decay, the black holes will evaporate and what is left will be a very lonely and empty place.
The Universe will have ceased converting mass into light, and it will be left in almost total darkness. Every once in a while the remaining photons, electrons, positrons and neutrinos will meet and dance, but they will soon continue their solitary journeys. The Universe, in any sense that we know it today, will be over.
The phase we are in now could be considered to be the slow death throes of the universe. But on a more upbeat note, this is its Indian summer. After those hectic early days I think we can all agree that it deserves a good rest.
http://www.sciencealert.c(...)erse-is-slowly-dying
Image: A representation of the evolution of the universe over 13.77 billion years. NASA / WMAP Science TeamDON'T PANIC, BUT THE UNIVERSE IS SLOWLY DYING
But as long as you know where your towel is, you should be fine.
We know that our Universe has already lived through great number of exciting phases. But new research released overnight shows the Universe has long passed its peak and is slowly but surely dying. The research was presented at the year’s largest gathering of astronomers at the International Astronomical Union’s General Assembly in Hawaii. But before we start writing any obituaries, let’s have a quick recap of the good times.
When the Universe was less than a second old and more than a billion degrees Celsius, it was hot enough for exotic particles to freely pop in and out of existence. As the Universe expanded, it cooled and was no longer able to produce hugely energetic particles. After a few seconds, the Universe was a sea of protons and neutrons, and after a few minutes it was mostly a dense fog of hydrogen and helium. In terms of building more complex matter, that was pretty much the end of the action for 400,000 years.
Then, quite suddenly, matter and radiation were decoupled and photons of light were able to free-stream across the Universe for the first time. This is all very exciting for cosmology, but something important had also happened to the hydrogen and helium: it could now hold onto electrons and create neutral atoms.
When the Universe was less than a second old and more than a billion degrees Celsius, it was hot enough for exotic particles to freely pop in and out of existence. As the Universe expanded, it cooled and was no longer able to produce hugely energetic particles. After a few seconds, the Universe was a sea of protons and neutrons, and after a few minutes it was mostly a dense fog of hydrogen and helium. In terms of building more complex matter, that was pretty much the end of the action for 400,000 years.
Then, quite suddenly, matter and radiation were decoupled and photons of light were able to free-stream across the Universe for the first time. This is all very exciting for cosmology, but something important had also happened to the hydrogen and helium: it could now hold onto electrons and create neutral atoms.
Early building blocks of life
This is another step on the path to making you and me: we need neutral hydrogen in order to form molecular hydrogen, we need this to efficiently cool pockets of gas that collapse rapidly to form the first stars, and we need stars to form the heavy elements such as carbon and oxygen that are the building blocks of life.
By this stage the Universe was a few hundred million years old, and it was now busy heating itself back up as these first stars irradiated the surrounding material. These stars were blowing themselves apart and dumping large quantities of heavy atomic species into space, producing many of the heavier elements we see today. Some of them may also have collapsed into black holes, sowing the seeds of some of the most massive galaxies that exist in the present day Universe.
After this early phase of forming the first stars, we began to see the first structures that resemble modern galaxies, but in a very messy and violent form. For the next few billion years galaxies smashed together to form more massive systems and star formation was rapidly turned on and off. This activity continued until the Universe was about 3 billion years old, a period we know as the peak of cosmic star formation. So the u=Universe got most of the exciting stuff out of the way really early on.
What has it been doing since then? It is slowly but steadily dying. It is still producing new stars every now and again, but the rate at which old stars are fading outstrips these bright young things.
A top down view of the major 3D redshift surveys of the local Universe with Earth at the centre. Each dot represents a single galaxy, and the direction shows their location on the sky. The distance from the centre shows the light travel time from Earth. Here we see the most recent 5 billion years of the Universe, which has taken thousands of nights of observing on some of the most massive telescopes to construct. ICRAR/GAMA
A top down view of the major 3D redshift surveys of the local Universe with Earth at the centre. Each dot represents a single galaxy, and the direction shows their location on the sky. The distance from the centre shows the light travel time from Earth. Here we see the most recent 5 billion years of the Universe, which has taken thousands of nights of observing on some of the most massive telescopes to construct. ICRAR/GAMAEnter the dark stuff
To exacerbate things even further, about 3 billion years ago a mysterious (and much studied) entity called dark energy began to dominate the energy contents of the Universe and accelerate everything apart (measuring this acceleration won Australian researcher Brian Schmidt and others a Nobel prize). The Universe had already started cooling off by this stage, so dark energy arriving on the scene really twisted the knife.
How do we know all of this? Well, we have been building the evidence for a while and careful models of galaxy evolution have already suggested that the Universe is fading, but we wanted to directly observe this effect over many billions of years.
In the past few years a large Australian led project called the Galaxy And Mass Assembly (GAMA) survey invested huge effort into measuring most of the energy output from stars. We had to observe nearby galaxies from the far-ultraviolet (where young stars produce much of their light) through the optical and the near-infrared (where most stars peak in energy output) all the way into the far-infrared (where star light absorbed by dust is re-emitted).
GAMA has been able to measure this huge span of radiation over the past 5 billion years for almost 200,000 galaxies, categorically establishing that the energy output of stars in the Universe is winding down.
A galaxy from the GAMA survey observed at different wavelengths from the far ultraviolet to the far infrared. The inset graph shows how much energy is being generated at different wavelengths. ICRAR/GAMA, CC BY-NC
A galaxy from the GAMA survey observed at different wavelengths from the far ultraviolet to the far infrared. The inset graph shows how much energy is being generated at different wavelengths. ICRAR/GAMA, CC BY-NCThe good news is that the stars made to date will still last many billions of years yet (including our own sun). Some of the smaller stars should keep shining for longer than the current age of the Universe. There are questions over what exactly the dominance of dark energy will mean in the long term, with some of more exotic theories speculating that it could tear everything apart in a 'Big Rip':
Less dramatic, and more likely given our current knowledge, is the theory that the Universe will continue to cool forever, and non gravitationally bound structures will steadily move apart from each other. After trillions of years we will only be able to see our own galaxy as the others will have raced too far away. After hundreds of trillions of years no new stars will be made anywhere at all.
Next our galaxy will eject most of its remaining stars into the cosmic void, and what is left will collapse into our central black hole. All matter as we know it will eventually decay, the black holes will evaporate and what is left will be a very lonely and empty place.
The Universe will have ceased converting mass into light, and it will be left in almost total darkness. Every once in a while the remaining photons, electrons, positrons and neutrinos will meet and dance, but they will soon continue their solitary journeys. The Universe, in any sense that we know it today, will be over.
The phase we are in now could be considered to be the slow death throes of the universe. But on a more upbeat note, this is its Indian summer. After those hectic early days I think we can all agree that it deserves a good rest.
http://www.sciencealert.c(...)erse-is-slowly-dying
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt.”— Bertrand Russell
Jongen vindt in Gelderland botten van prehistorische grottenleeuw
De nu tienjarige Enzo Smink uit het Gelderse dorp Wekerom heeft een volstrekt unieke vondst gedaan. Op een afgelegen strandje in de buurt heeft hij de onderkaak gevonden van een zeldzame prehistorische grottenleeuw.
Dat heeft oertijdmuseum De Groene Poort in Boxtel zondag gemeld.
Smink deed de ontdekking al in de zomer van 2012, maar niemand besefte toen wat de knul had gevonden. De restanten belandden in een doosje bij zijn oma.
Pas toen de jongen eerder dit jaar de botjes weer tevoorschijn haalde voor een spreekbeurt, besloot zijn moeder een foto ervan naar specialisten te sturen.
"Een prehistorische vondst van dit formaat wordt vermoedelijk eens in de twintig jaar gedaan", stelt directeur René Fraaije van het museum tegenover NU.nl. "Grottenleeuwen waren in die tijd al zeldzaam, laat staan dat er tienduizend jaar later nog vaak botten worden gevonden."
Grottekeningen
De grottenleeuw was het grootste roofdier uit de tijd van de mammoeten. Het dier kwam toen voor in het grootste deel van het huidige Europa. De naam verwijst niet naar de leefwijze van de enorme katachtige, maar naar de plek waar de meeste restanten van de leeuw gevonden zijn.
Het dier stierf uit aan het einde van de laatste ijstijd, pakweg tienduizend jaar geleden. Dit kwam door het veranderde klimaat en het uitsterven van de prooidieren waar de leeuw zich mee voedde. De meeste informatie over het uiterlijk van de grottenleeuw is afgeleid van prehistorische grottekeningen.
Enzo Smink draagt de vondst maandag officieel over aan het oertijdmuseum. Daar krijgt de onderkaak een speciale ereplek in de collectie.
Bron: nu.nl
Zie ook: Panthera Leo Spelaea.
De nu tienjarige Enzo Smink uit het Gelderse dorp Wekerom heeft een volstrekt unieke vondst gedaan. Op een afgelegen strandje in de buurt heeft hij de onderkaak gevonden van een zeldzame prehistorische grottenleeuw.
Dat heeft oertijdmuseum De Groene Poort in Boxtel zondag gemeld.
Smink deed de ontdekking al in de zomer van 2012, maar niemand besefte toen wat de knul had gevonden. De restanten belandden in een doosje bij zijn oma.
Pas toen de jongen eerder dit jaar de botjes weer tevoorschijn haalde voor een spreekbeurt, besloot zijn moeder een foto ervan naar specialisten te sturen.
"Een prehistorische vondst van dit formaat wordt vermoedelijk eens in de twintig jaar gedaan", stelt directeur René Fraaije van het museum tegenover NU.nl. "Grottenleeuwen waren in die tijd al zeldzaam, laat staan dat er tienduizend jaar later nog vaak botten worden gevonden."
Grottekeningen
De grottenleeuw was het grootste roofdier uit de tijd van de mammoeten. Het dier kwam toen voor in het grootste deel van het huidige Europa. De naam verwijst niet naar de leefwijze van de enorme katachtige, maar naar de plek waar de meeste restanten van de leeuw gevonden zijn.
Het dier stierf uit aan het einde van de laatste ijstijd, pakweg tienduizend jaar geleden. Dit kwam door het veranderde klimaat en het uitsterven van de prooidieren waar de leeuw zich mee voedde. De meeste informatie over het uiterlijk van de grottenleeuw is afgeleid van prehistorische grottekeningen.
Enzo Smink draagt de vondst maandag officieel over aan het oertijdmuseum. Daar krijgt de onderkaak een speciale ereplek in de collectie.
Bron: nu.nl
Zie ook: Panthera Leo Spelaea.
Niet meer aanwezig in dit forum.
Braziliaan maakt motorfiets die op water loopt.
500 KM op 1 liter water.
http://www.zie.nl/video/o(...)n-WATER/keizq26fpikg
Kan en wil iemand me kort en in simpele termen uitleggen hoe dat ongeveer werkt ?
[ Bericht 38% gewijzigd door mannenkokengewoonbeter op 25-08-2015 13:45:22 ]
500 KM op 1 liter water.
http://www.zie.nl/video/o(...)n-WATER/keizq26fpikg
Kan en wil iemand me kort en in simpele termen uitleggen hoe dat ongeveer werkt ?
[ Bericht 38% gewijzigd door mannenkokengewoonbeter op 25-08-2015 13:45:22 ]
bivd kijkt met u mee.
28-08-2015
Quantumteleportatie verwijst bezwaren Einstein naar prullenbak
Het is een mooie dag voor liefhebbers van quantumfysica in z’n meest zuivere vorm. Een nieuw experiment aan de TU Delft, uitgevoerd door de onderzoeksgroep van Ronald Hanson aan het QuTech-lab, heeft bewezen dat een van de meest contra-intuïtieve eigenschappen van de beroemde theorie echt is.
.
De qubit die Ronald Hanson gebruikt bij zijn experimenten heeft een schaal van enkele tientallen micrometers. Bron: TU Delft
Hanson en collega’s deden dat door te bewijzen dat twee deeltjes die 1,3 kilometer uit elkaar zaten, elkaars eigenschappen deelden. Dat meldt Nature News deze ochtend op basis van een voorpublicatie van het resultaat op de wetenschappelijke voorpublicatiesite Arxiv.
Bizarre eigenschappen
De test die de onderzoekers deden, vormt een eerste stap richting teleportatie van quantuminformatie over grote afstanden. Bij dat soort teleportatie zijn twee bizarre eigenschappen van de quantumfysica van belang. De eerste daarvan is verstrengeling, het idee dat de eigenschappen van twee deeltjes onlosmakelijk met elkaar verbonden kunnen raken en vervolgens elkaar eigenschappen delen. Dat hangt echter samen met een tweede gekkigheid van de quantummechanica die bekendstaat onder de term ‘superpositie’, het bijzondere gegeven dat twee deeltjes tegelijk meerdere eigenschappen kunnen hebben die elkaar klassiek uitsluiten. Zo kunnen quantumdeeltjes rustig op twee plaatsen tegelijkertijd zijn en kunnen qubits, de quantumversies van de klassieke nullen en enen van digitale informatie, tegelijkertijd nul én één zijn.
Die superpositie blijft gelden totdat je een deeltje meet – dan kiest het één van de opties, bijvoorbeeld een enkele positie of alleen de waarde nul of een. Wanneer twee quantumdeeltjes dan bovendien ook nog verstrengeld zijn, zorgt zo’n meting aan het ene deeltje ook direct voor een reactie in de ander. Meet je het ene deeltje als nul, dan is het andere daarna bijvoorbeeld ineens 1.
Teleporteren
Dat gegeven zorgt ervoor dat je een quantumtoestand kunt teleporteren, een term die bewust verwijst naar het verplaatsen van mensen van en naar planeten en ruimteschepen in de sciencefictionserie Star Trek. Bij quantumteleportatie verplaats je alleen geen mensen, maar informatie. Deze gaat daarbij direct – zonder dat er tijd voorbij gaat – van de ene plek naar de andere. Op die manier kun je informatie in theorie zelfs sneller verplaatsen dan het licht, een gegeven waar Einstein openbaar grote twijfels over uitte.
In 2014 lukte het Hanson en collega’s al om de informatie in een qubit over een afstand van 3 meter te teleporteren, destijds een wereldrecord. In plaats daarvan hebben zij quantuminformatie nu verstrengeld over 1,3 kilometer en metingen gedaan via kabels die onder het terrein van de TU Delft doorliepen. Dat is de belangrijkste eerste stap op weg naar echte quantumteleportatie.
Einsteins ongelijk
Ronald Hanson is één van de genomineerden in onze top 25 grootste wetenschappelijke talenten van de lage landen. Bekijk hier de complete lijst.
Die sprong voorwaarts is niet alleen groot nieuws omdat het teleportatie over grote afstanden dichterbij brengt, iets dat tot nog toe technisch moeilijk te realiseren was. Veel belangrijker is dat het ervoor zorgt dat verstrengeling nu loophole free is. Dat wil zeggen: er is niet stiekem iets anders aan de hand, zoals Einstein dacht. Verstrengeling bestaat echt.
Over kortere afstanden speelt bijvoorbeeld de zogeheten communication loop hole onderzoekers nog parten wanneer zij hun resultaten willen interpreteren. Omdat metingen doen tijd kost, zou het meten van het ene deeltje soms best op de een of andere manier het resultaat van de andere meting kunnen beïnvloeden, zonder dat de lichtsnelheid wordt verbroken. Bij de afstand van 1,3 kilometer waar Hanson en collega’s dit onderzoek op deden, is daar echter geen sprake meer van. Alleen daadwerkelijke verstrengeling waarbij de twee deeltjes samen één geheel vormen, zelfs als ze een grote afstand uit elkaar zitten, lijkt nu nog een verklaring voor het gevonden resultaat te bieden.
Overigens vormen de resultaten van dit experiment ook een mooie stap vooruit naar een echt quantuminternet, een voor hackers onkraakbaar communicatiesysteem. In de toekomst zullen quantumcomputers op dat internet kunnen inloggen en zo hun quantuminformatie kunnen uitwisselen. De bij dit onderzoek betrokken qubits en verbindingen moeten in de toekomst de bouwblokken van zo’n quantuminternet worden.
Nobelprijs
Leo Kouwenhoven, initiatiefnemer van het QuTech-lab waaraan deze ontdekking werd gedaan, spreekt op ons top-25 evenement uitgebreid over de quantumcomputer (tickets hier).
Op dit moment wil Hanson zelf nog niet reageren op zijn resultaten, laat hij via de mail weten. De publicatie op Arxiv is een voorpublicatie die nog niet door vakcollega’s aan de standaard wetenschappelijke controle is onderworpen. Zodra zij hebben bevestigd dat het team van Hanson inderdaad heeft gevonden wat ze in hun voorpublicatie stellen, volgt een echte publicatie en mogen de onderzoekers hun resultaten ook verder toelichten.
Toch is het enthousiasme onder quantumfysici over dit eerste resultaat nu al groot. ‘Het zou mij niet verbazen als we de komende jaren een van de auteurs van dit artikel, samen met die van wat oudere experimenten zoals die van Aspect, terugzien bij de nominaties voor de Nobelprijzen’, zei quantumfysicus Matthew Leifer tegen Nature News. ‘Zo spannend is dit.’
Edit: per abuis werd in een vorige versie van dit bericht gemeld dat de onderzoekers al daadwerkelijk informatie over 1,3 kilometer hadden geteleporteerd. In plaats daarvan hebben zij een voorstadium van teleportatie bereikt, waarbij zij (zoals in de eerste versie ook al stond) bewezen dat de deeltjes verstrengeld waren.
Altijd op de hoogte blijven van het laatste wetenschapsnieuws? Meld je nu aan voor de New Scientist nieuwsbrief.
(newscientist.nl)
Quantumteleportatie verwijst bezwaren Einstein naar prullenbak
Het is een mooie dag voor liefhebbers van quantumfysica in z’n meest zuivere vorm. Een nieuw experiment aan de TU Delft, uitgevoerd door de onderzoeksgroep van Ronald Hanson aan het QuTech-lab, heeft bewezen dat een van de meest contra-intuïtieve eigenschappen van de beroemde theorie echt is.
.
De qubit die Ronald Hanson gebruikt bij zijn experimenten heeft een schaal van enkele tientallen micrometers. Bron: TU Delft
Hanson en collega’s deden dat door te bewijzen dat twee deeltjes die 1,3 kilometer uit elkaar zaten, elkaars eigenschappen deelden. Dat meldt Nature News deze ochtend op basis van een voorpublicatie van het resultaat op de wetenschappelijke voorpublicatiesite Arxiv.
Bizarre eigenschappen
De test die de onderzoekers deden, vormt een eerste stap richting teleportatie van quantuminformatie over grote afstanden. Bij dat soort teleportatie zijn twee bizarre eigenschappen van de quantumfysica van belang. De eerste daarvan is verstrengeling, het idee dat de eigenschappen van twee deeltjes onlosmakelijk met elkaar verbonden kunnen raken en vervolgens elkaar eigenschappen delen. Dat hangt echter samen met een tweede gekkigheid van de quantummechanica die bekendstaat onder de term ‘superpositie’, het bijzondere gegeven dat twee deeltjes tegelijk meerdere eigenschappen kunnen hebben die elkaar klassiek uitsluiten. Zo kunnen quantumdeeltjes rustig op twee plaatsen tegelijkertijd zijn en kunnen qubits, de quantumversies van de klassieke nullen en enen van digitale informatie, tegelijkertijd nul én één zijn.
Die superpositie blijft gelden totdat je een deeltje meet – dan kiest het één van de opties, bijvoorbeeld een enkele positie of alleen de waarde nul of een. Wanneer twee quantumdeeltjes dan bovendien ook nog verstrengeld zijn, zorgt zo’n meting aan het ene deeltje ook direct voor een reactie in de ander. Meet je het ene deeltje als nul, dan is het andere daarna bijvoorbeeld ineens 1.
Teleporteren
Dat gegeven zorgt ervoor dat je een quantumtoestand kunt teleporteren, een term die bewust verwijst naar het verplaatsen van mensen van en naar planeten en ruimteschepen in de sciencefictionserie Star Trek. Bij quantumteleportatie verplaats je alleen geen mensen, maar informatie. Deze gaat daarbij direct – zonder dat er tijd voorbij gaat – van de ene plek naar de andere. Op die manier kun je informatie in theorie zelfs sneller verplaatsen dan het licht, een gegeven waar Einstein openbaar grote twijfels over uitte.
In 2014 lukte het Hanson en collega’s al om de informatie in een qubit over een afstand van 3 meter te teleporteren, destijds een wereldrecord. In plaats daarvan hebben zij quantuminformatie nu verstrengeld over 1,3 kilometer en metingen gedaan via kabels die onder het terrein van de TU Delft doorliepen. Dat is de belangrijkste eerste stap op weg naar echte quantumteleportatie.
Einsteins ongelijk
Ronald Hanson is één van de genomineerden in onze top 25 grootste wetenschappelijke talenten van de lage landen. Bekijk hier de complete lijst.
Die sprong voorwaarts is niet alleen groot nieuws omdat het teleportatie over grote afstanden dichterbij brengt, iets dat tot nog toe technisch moeilijk te realiseren was. Veel belangrijker is dat het ervoor zorgt dat verstrengeling nu loophole free is. Dat wil zeggen: er is niet stiekem iets anders aan de hand, zoals Einstein dacht. Verstrengeling bestaat echt.
Over kortere afstanden speelt bijvoorbeeld de zogeheten communication loop hole onderzoekers nog parten wanneer zij hun resultaten willen interpreteren. Omdat metingen doen tijd kost, zou het meten van het ene deeltje soms best op de een of andere manier het resultaat van de andere meting kunnen beïnvloeden, zonder dat de lichtsnelheid wordt verbroken. Bij de afstand van 1,3 kilometer waar Hanson en collega’s dit onderzoek op deden, is daar echter geen sprake meer van. Alleen daadwerkelijke verstrengeling waarbij de twee deeltjes samen één geheel vormen, zelfs als ze een grote afstand uit elkaar zitten, lijkt nu nog een verklaring voor het gevonden resultaat te bieden.
Overigens vormen de resultaten van dit experiment ook een mooie stap vooruit naar een echt quantuminternet, een voor hackers onkraakbaar communicatiesysteem. In de toekomst zullen quantumcomputers op dat internet kunnen inloggen en zo hun quantuminformatie kunnen uitwisselen. De bij dit onderzoek betrokken qubits en verbindingen moeten in de toekomst de bouwblokken van zo’n quantuminternet worden.
Nobelprijs
Leo Kouwenhoven, initiatiefnemer van het QuTech-lab waaraan deze ontdekking werd gedaan, spreekt op ons top-25 evenement uitgebreid over de quantumcomputer (tickets hier).
Op dit moment wil Hanson zelf nog niet reageren op zijn resultaten, laat hij via de mail weten. De publicatie op Arxiv is een voorpublicatie die nog niet door vakcollega’s aan de standaard wetenschappelijke controle is onderworpen. Zodra zij hebben bevestigd dat het team van Hanson inderdaad heeft gevonden wat ze in hun voorpublicatie stellen, volgt een echte publicatie en mogen de onderzoekers hun resultaten ook verder toelichten.
Toch is het enthousiasme onder quantumfysici over dit eerste resultaat nu al groot. ‘Het zou mij niet verbazen als we de komende jaren een van de auteurs van dit artikel, samen met die van wat oudere experimenten zoals die van Aspect, terugzien bij de nominaties voor de Nobelprijzen’, zei quantumfysicus Matthew Leifer tegen Nature News. ‘Zo spannend is dit.’
Edit: per abuis werd in een vorige versie van dit bericht gemeld dat de onderzoekers al daadwerkelijk informatie over 1,3 kilometer hadden geteleporteerd. In plaats daarvan hebben zij een voorstadium van teleportatie bereikt, waarbij zij (zoals in de eerste versie ook al stond) bewezen dat de deeltjes verstrengeld waren.
Altijd op de hoogte blijven van het laatste wetenschapsnieuws? Meld je nu aan voor de New Scientist nieuwsbrief.
(newscientist.nl)
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
03-09-2015
Quantumverstrengeling slaagt voor ultieme test
Delfts experiment beslecht discussie van bijna een eeuw oud
Albert Einstein vond het helemaal niks. Volgens de quantummechanica kunnen twee verstrengelde deeltjes ogenblikkelijk elkaars invloed voelen op grote afstand, waarbij ze schijnbaar de lichtsnelheid doorbreken. Een Delfts experiment laat nu zien dat verstrengeling echt die ‘spookachtige interactie’ is die Einstein voor onmogelijk hield.
Je moet heel wat uit de kast halen om te bewijzen dat Albert Einstein ongelijk had. Maar het is wetenschappers van de Technische Universiteit Delft na bijna een eeuw gelukt. Ze hebben voor het eerst een experiment uitgevoerd dat geen enkele twijfel laat bestaan: er is daadwerkelijk een door Einstein gevreesde spukhaften Fernwirkung (spookachtige interactie op afstand).
In het experiment onder leiding van hoogleraar Ronald Hanson (TU Delft) ging het om de interactie tussen twee elektronen in verschillende labs op 1280 meter afstand. Deze deeltjes werden in het experiment met elkaar verstrengeld. Dat betekent dat de draairichting van beide elektronen onlosmakelijk met elkaar verbonden wordt. Als het ene elektron bijvoorbeeld linksom draait dan draait het andere volgens de quantummechanica onherroepelijk rechtsom.
Ronald Hanson bij een opstelling waarmee eerder twee elektronen werden verstrengeld over een afstand van drie meter. Dat experiment is nu herhaald over een afstand van 1,3 kilometer.
TU Delft/Kavli-instituut
De gekoppelde draairichtingen van beide elektronen zijn volgens de quantummechanica volledig willekeurig en worden pas bepaald op het moment dat ze worden gemeten. Met juist dat laatste had Einstein moeite. Hij hield vol dat elektronen in zo’n experiment van te voren al moeten ‘weten’ wat hun uitkomst wordt, óf dat ze stiekem toch met elkaar communiceren. Het Delftse experiment veegt zo’n ‘verborgen mechanisme’ nu echter van tafel.
De resultaten van het experiment werden vorige week online gepubliceerd in een voorpublicatie. Het artikel moet dus nog officieel gepubliceerd worden, maar dat lijkt slechts een kwestie van tijd. Het nieuws werd accuut opgepikt door Nature die het woord Nobelprijs niet schuwde.
Alle gaten dicht
De afgelopen jaren zijn er al talloze succesvolle experimenten met verstrengelde deeltjes gedaan, waaronder teleportatie-experimenten die deze verstrengeling gebruiken om informatie te versturen. Zo kunnen fotonen over een afstand van meer dan honderd kilometer worden geteleporteerd, en slaagde de groep van Hanson er vorig jaar voor het eerst in om een betrouwbare elektronteleportatie op enkele meters uit te voeren.
John Stewart Bell.
Wikimedia Commons
Maar wáárom is juist dit Delftse experiment zo bijzonder? Dat heeft alles te maken met de twijfel die Einstein in de jaren dertig al uitte. Hij geloofde dat deeltjes alleen beïnvloed konden worden door de directe omgeving en niet door een deeltje dat er in theorie oneindig ver van verwijderd is. Toch was dat precies wat de verstrengeling uit de quantummechanica betekent.
In 1964 kwam de Britse natuurkundige en wiskundige John Bell met een oplossing. Althans hij bedacht een experiment, de Bell-test, waarmee Einsteins gelijk of ongelijk kon worden bewezen. In de test worden twee deeltjes verstrengeld en op een bepaalde manier gemeten, zodat hun spins afhankelijk van de soort meting overeenkomen of juist verschillen. Het mooie van die test is dat Einsteins ‘realiteit’ een andere uitkomst geeft dan die van de quantummechanica.
De Bell-test is meerdere keren uitgevoerd, voor het eerst in de jaren tachtig. Was Einsteins twijfel dan eindelijk volledig van tafel? Nee, want er bleven in de experimenten altijd kleine achterdeurtjes openstaan die verstrengeling konden verklaren via een ‘verborgen mechanisme’.
De eerste loophole was dat er een mogelijkheid bestond dat de verstrengelde deeltjes stiekem toch met elkaar communiceerden, zonder dat we dat doorhebben. Dit kan in een experiment worden ondervangen door de spins van twee verstrengelde deeltjes te meten binnen de tijd waarin ze (binnen de grenzen van de lichtsnelheid) de kans hebben om met elkaar te communiceren.
Een tweede punt is dat eigenlijk alle verstrengelingspogingen goed moeten gaan. Slaagt om wat voor reden dan ook maar een deel van alle experimenten – iets wat bij verstrengeling van fotonen vaak gebeurde – dan is het theoretisch mogelijk dat wetenschappers alleen de uitkomsten registreren die toevallig overeenkomen.
Georchestreerd samenspel
In Delft zijn nu voor het eerst deze twee achterdeurtjes van de Bell-test gedicht binnen één experiment. Hanson en collega’s gebruikten een door hen ontwikkeld betrouwbare opstelling voor het maken van verstrengelde deeltjes. Bovendien zat er tussen het verstrengelde elektronpaar 1280 meter, waardoor het mogelijk was om de spinmetingen te doen voordat ze de kans kregen op wat voor manier dan ook met elkaar te communiceren.
De opstelling waarmee quantuminformatie wordt geteleporteerd op de campus van de TU Delft.
Hensen et al.
Het experiment is een zorgvuldig georchestreerd samenspel tussen verschillende opstellingen op de campus van de Technische Universiteit, die met elkaar verbonden zijn met een speciaal hiervoor aangelegd glasvezelnetwerk. Op de twee plekken dienen stukjes diamant als een zogenoemde elektronenval. Elektronen kunnen hierin ‘gevangen’ worden en worden gemanipuleerd door een laser.
De elektronen worden met elkaar verstrengeld via een derde locatie, ruwweg in het midden van de twee elektronenvallen. Met lasers worden beide elektronen aangeslagen die vervolgens meteen een lichtdeeltje uitzenden. Deze fotonen reizen per glasvezel naar de derde locatie waar ze tegelijkertijd op een halfdoorlatende spiegel vallen.
Twee detectoren achter de doorlaatbare spiegel meten de lichtdeeltjes die ófwel door de spiegel zijn gevallen of erdoor zijn gereflecteerd. Doordat het voor de detectoren niet duidelijk is van welk elektron het foton afkomstig is, raken de twee elektronen met elkaar verstrengeld. Hun draairichtingen worden innig met elkaar verbonden en een meting aan het ene deeltje beïnvloedt het andere deeltje.
Animatie van de verstrengeling van twee elektronen (blauw) die worden verstrengeld via twee fotonen die samen op een spiegel in het midden vallen.
Het verstrengelingsexperiment werd 245 keer herhaald en het grootste aantal keren daarvan deden de spins van de elektronen wat er volgens de quantummechanica van hen verwacht werd. Statistisch gezien was dit aantal experimenten genoeg om de Bell-test te laten slagen, en Einsteins ongelijk te bewijzen.
Heilige graal
Richard Gill, professor Mathematische Statistiek van de Universiteit Leiden, was zijdelings bij het onderzoek betrokken en is ontzettend blij met het resultaat. “Dit is al meer dan vijftig jaar de heilige graal in de quantuminformatica”, zegt hij. “Natuurlijk, de meeste wetenschappers waren al overtuigd van quantumwetten, maar toch denk ik dat er nog natuurkundigen waren die er op een of andere manier aan twijfelden.”
Gill zegt dat het experiment nu vooral nog vaak herhaald moet worden om de onzekerheid verder omlaag te krijgen. “Dit resultaat kan gemiddeld eens in de veertig keer ook door puur toeval ontstaan. Dat kan nog een stuk beter.” Overigens wilde Hanson zelf nog niet reageren op de resultaten omdat het onderzoek officieel nog niet gepubliceerd is.
Uiteindelijk is het experiment ook belangrijk voor de eerder genoemde teleportatie, waarmee quantuminformatie verstuurd wordt tussen bijvoorbeeld quantumcomputers. De theorie stelt dat dit honderd procent veilig kan, zonder dat iemand meeluistert. “Theoretisch gaven de loopholes hackers echter de kans om de boel te belazeren”, laat Gill weten.
Bron
•Hensen B. et al., Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km, voorpublicatie arXiv (24 augustus 2015), http://arxiv.org/abs/1508.05949
(kennislink)
Quantumverstrengeling slaagt voor ultieme test
Delfts experiment beslecht discussie van bijna een eeuw oud
Albert Einstein vond het helemaal niks. Volgens de quantummechanica kunnen twee verstrengelde deeltjes ogenblikkelijk elkaars invloed voelen op grote afstand, waarbij ze schijnbaar de lichtsnelheid doorbreken. Een Delfts experiment laat nu zien dat verstrengeling echt die ‘spookachtige interactie’ is die Einstein voor onmogelijk hield.
Je moet heel wat uit de kast halen om te bewijzen dat Albert Einstein ongelijk had. Maar het is wetenschappers van de Technische Universiteit Delft na bijna een eeuw gelukt. Ze hebben voor het eerst een experiment uitgevoerd dat geen enkele twijfel laat bestaan: er is daadwerkelijk een door Einstein gevreesde spukhaften Fernwirkung (spookachtige interactie op afstand).
In het experiment onder leiding van hoogleraar Ronald Hanson (TU Delft) ging het om de interactie tussen twee elektronen in verschillende labs op 1280 meter afstand. Deze deeltjes werden in het experiment met elkaar verstrengeld. Dat betekent dat de draairichting van beide elektronen onlosmakelijk met elkaar verbonden wordt. Als het ene elektron bijvoorbeeld linksom draait dan draait het andere volgens de quantummechanica onherroepelijk rechtsom.
Ronald Hanson bij een opstelling waarmee eerder twee elektronen werden verstrengeld over een afstand van drie meter. Dat experiment is nu herhaald over een afstand van 1,3 kilometer.
TU Delft/Kavli-instituut
De gekoppelde draairichtingen van beide elektronen zijn volgens de quantummechanica volledig willekeurig en worden pas bepaald op het moment dat ze worden gemeten. Met juist dat laatste had Einstein moeite. Hij hield vol dat elektronen in zo’n experiment van te voren al moeten ‘weten’ wat hun uitkomst wordt, óf dat ze stiekem toch met elkaar communiceren. Het Delftse experiment veegt zo’n ‘verborgen mechanisme’ nu echter van tafel.
De resultaten van het experiment werden vorige week online gepubliceerd in een voorpublicatie. Het artikel moet dus nog officieel gepubliceerd worden, maar dat lijkt slechts een kwestie van tijd. Het nieuws werd accuut opgepikt door Nature die het woord Nobelprijs niet schuwde.
Alle gaten dicht
De afgelopen jaren zijn er al talloze succesvolle experimenten met verstrengelde deeltjes gedaan, waaronder teleportatie-experimenten die deze verstrengeling gebruiken om informatie te versturen. Zo kunnen fotonen over een afstand van meer dan honderd kilometer worden geteleporteerd, en slaagde de groep van Hanson er vorig jaar voor het eerst in om een betrouwbare elektronteleportatie op enkele meters uit te voeren.
John Stewart Bell.
Wikimedia Commons
Maar wáárom is juist dit Delftse experiment zo bijzonder? Dat heeft alles te maken met de twijfel die Einstein in de jaren dertig al uitte. Hij geloofde dat deeltjes alleen beïnvloed konden worden door de directe omgeving en niet door een deeltje dat er in theorie oneindig ver van verwijderd is. Toch was dat precies wat de verstrengeling uit de quantummechanica betekent.
In 1964 kwam de Britse natuurkundige en wiskundige John Bell met een oplossing. Althans hij bedacht een experiment, de Bell-test, waarmee Einsteins gelijk of ongelijk kon worden bewezen. In de test worden twee deeltjes verstrengeld en op een bepaalde manier gemeten, zodat hun spins afhankelijk van de soort meting overeenkomen of juist verschillen. Het mooie van die test is dat Einsteins ‘realiteit’ een andere uitkomst geeft dan die van de quantummechanica.
De Bell-test is meerdere keren uitgevoerd, voor het eerst in de jaren tachtig. Was Einsteins twijfel dan eindelijk volledig van tafel? Nee, want er bleven in de experimenten altijd kleine achterdeurtjes openstaan die verstrengeling konden verklaren via een ‘verborgen mechanisme’.
De eerste loophole was dat er een mogelijkheid bestond dat de verstrengelde deeltjes stiekem toch met elkaar communiceerden, zonder dat we dat doorhebben. Dit kan in een experiment worden ondervangen door de spins van twee verstrengelde deeltjes te meten binnen de tijd waarin ze (binnen de grenzen van de lichtsnelheid) de kans hebben om met elkaar te communiceren.
Een tweede punt is dat eigenlijk alle verstrengelingspogingen goed moeten gaan. Slaagt om wat voor reden dan ook maar een deel van alle experimenten – iets wat bij verstrengeling van fotonen vaak gebeurde – dan is het theoretisch mogelijk dat wetenschappers alleen de uitkomsten registreren die toevallig overeenkomen.
Georchestreerd samenspel
In Delft zijn nu voor het eerst deze twee achterdeurtjes van de Bell-test gedicht binnen één experiment. Hanson en collega’s gebruikten een door hen ontwikkeld betrouwbare opstelling voor het maken van verstrengelde deeltjes. Bovendien zat er tussen het verstrengelde elektronpaar 1280 meter, waardoor het mogelijk was om de spinmetingen te doen voordat ze de kans kregen op wat voor manier dan ook met elkaar te communiceren.
De opstelling waarmee quantuminformatie wordt geteleporteerd op de campus van de TU Delft.
Hensen et al.
Het experiment is een zorgvuldig georchestreerd samenspel tussen verschillende opstellingen op de campus van de Technische Universiteit, die met elkaar verbonden zijn met een speciaal hiervoor aangelegd glasvezelnetwerk. Op de twee plekken dienen stukjes diamant als een zogenoemde elektronenval. Elektronen kunnen hierin ‘gevangen’ worden en worden gemanipuleerd door een laser.
De elektronen worden met elkaar verstrengeld via een derde locatie, ruwweg in het midden van de twee elektronenvallen. Met lasers worden beide elektronen aangeslagen die vervolgens meteen een lichtdeeltje uitzenden. Deze fotonen reizen per glasvezel naar de derde locatie waar ze tegelijkertijd op een halfdoorlatende spiegel vallen.
Twee detectoren achter de doorlaatbare spiegel meten de lichtdeeltjes die ófwel door de spiegel zijn gevallen of erdoor zijn gereflecteerd. Doordat het voor de detectoren niet duidelijk is van welk elektron het foton afkomstig is, raken de twee elektronen met elkaar verstrengeld. Hun draairichtingen worden innig met elkaar verbonden en een meting aan het ene deeltje beïnvloedt het andere deeltje.
Animatie van de verstrengeling van twee elektronen (blauw) die worden verstrengeld via twee fotonen die samen op een spiegel in het midden vallen.
Het verstrengelingsexperiment werd 245 keer herhaald en het grootste aantal keren daarvan deden de spins van de elektronen wat er volgens de quantummechanica van hen verwacht werd. Statistisch gezien was dit aantal experimenten genoeg om de Bell-test te laten slagen, en Einsteins ongelijk te bewijzen.
Heilige graal
Richard Gill, professor Mathematische Statistiek van de Universiteit Leiden, was zijdelings bij het onderzoek betrokken en is ontzettend blij met het resultaat. “Dit is al meer dan vijftig jaar de heilige graal in de quantuminformatica”, zegt hij. “Natuurlijk, de meeste wetenschappers waren al overtuigd van quantumwetten, maar toch denk ik dat er nog natuurkundigen waren die er op een of andere manier aan twijfelden.”
Gill zegt dat het experiment nu vooral nog vaak herhaald moet worden om de onzekerheid verder omlaag te krijgen. “Dit resultaat kan gemiddeld eens in de veertig keer ook door puur toeval ontstaan. Dat kan nog een stuk beter.” Overigens wilde Hanson zelf nog niet reageren op de resultaten omdat het onderzoek officieel nog niet gepubliceerd is.
Uiteindelijk is het experiment ook belangrijk voor de eerder genoemde teleportatie, waarmee quantuminformatie verstuurd wordt tussen bijvoorbeeld quantumcomputers. De theorie stelt dat dit honderd procent veilig kan, zonder dat iemand meeluistert. “Theoretisch gaven de loopholes hackers echter de kans om de boel te belazeren”, laat Gill weten.
Bron
•Hensen B. et al., Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km, voorpublicatie arXiv (24 augustus 2015), http://arxiv.org/abs/1508.05949
(kennislink)
Death Makes Angels of us all
And gives us wings where we had shoulders
Smooth as raven' s claws...
And gives us wings where we had shoulders
Smooth as raven' s claws...
