[CENTRAAL] Wetenschap & Technologie in het Nieuws 3

HOW OCTOPUSES CO-ORDINATE THEIR ARMS

By Victoria Gill
Science reporter, BBC News

16 April 2015


The study is the first to examine how octopuses co-ordinate their eight, flexible limbs as they crawl

With the aid of high-speed cameras, scientists have revealed how octopuses co-ordinate their arms to crawl.

Researchers from the Hebrew University of Jerusalem filmed crawling octopuses to work out exactly how the animals used their almost limitlessly flexible arms when they move.

This revealed the surprising simplicity of their motion; they just choose which arm to use to push themselves along.

The findings are published in the journal Current Biology.

The study is the first detailed analysis of exactly how octopuses manages to move without a rigid skeleton.

How octopuses control and move their soft bodies is of interest to engineers who aim to design biologically inspired robots.

"People want to build soft robots for medical purposes and rescue operations," said Dr Guy Levy, one of the researchers involved in the project.

Such soft-bodied, octopus-inspired arms would not be limited by fixed joints, he explained. This could be useful to access narrow, difficult to reach spaces - perhaps getting help to people trapped at the scene of a collapsed building.

Pick a leg

To find out the secrets of the octopus's remarkably efficient movement, Dr Levy and his colleague Prof Benny Hochner videoed the animals from underneath as they crawled, and analysed their motion frame by frame.

"The octopus has found a very simple solution to a potentially complicated problem"
Guy Levy , Hebrew University of Jerusalem

This detailed study showed that, by shortening and lengthening, each arm pushed the body in only one direction.

"So the octopus only has to decide which arm to use for the pushing - it doesn't need to decide which direction this arm will push," explained Dr Levy.

"[It has] found a very simple solution to a potentially complicated problem - it just has to pick which arm to recruit."

And because the creatures are able to push off any of their eight legs, they are able to crawl in any direction - no matter which way their body is facing. And, uniquely, there is no rhythm or pattern to their undulating limb movements

The scientists' next step is to delve into the internal circuitry of the octopus nervous system, to find out exactly how this co-ordinated crawling is controlled.

Dr Levy added: "Every time we try to understand something new about the octopus, there are new surprises."

http://www.bbc.com/news/science-environment-32319705

THE LARGEST KNOWN STRUCTURE IN THE UNIVERSE IS A HOLE 1.8 BILLION LIGHT-YEARS ACROSS

Literally a whole lot of nothing.

FIONA MACDONALD

21 APR 2015

Astronomers have stumbled across the biggest object ever detected in the Universe… and it’s a void that stretches for 1.8 billion light years.

Distinguishable by its emptiness, the ‘supervoid’, as it's being called, isn't the only hole in the Universe, but it's the biggest patch we've found, and is abnormal in the typically evenly distributed Universe.
The supervoid was spotted by scientists trying to explain an unusually cool patch in the radiation left over from the Big Bang, known as the Universe’s cosmic microwave background. You can see this patch, which researchers named the 'Cold Spot', circled in the image above, taken by the European Space Agency's (ESA) Planck telescope.

For the past decade, researchers have been extremely interested in the Cold Spot, because it doesn't fit with our current understanding of how the Universe evolved. While a few small warm and cold patches are expected, we shouldn't see such big cold patches, according to the current model.

So an international team of astronomers decided to investigate further, and stumbled across the hole. Although the void isn’t entirely empty, there are an estimated 10,000 galaxies missing from the patch of sky.

Previous studies had missed the supervoid as they were looking too far back - the researchers used the Pan-STARRS1 telescope in Hawaii, and NASA's Wide Field Survey Explorer to count the number of galaxies in a patch of sky just 3 billion light years away.

"This is the greatest supervoid ever discovered," one of the researchers András Kovács, from the Eötvös Loránd University in Budapest, told Hannah Devlin over at The Guardian. "In combination of size and emptiness, our supervoid is still a very rare event. We can only expect a few supervoids this big in the observable universe."

The supervoid isn't actually a vacuum, but because it's so sparse - it contains around 20 percent less matter than the rest of the Universe - it sucks energy from light travelling through it, partially contributing to the Cold Spot's unusually low temperature.

But, frustratingly, it still doesn't fully explain why that region of the sky is so cold.

"The void itself I’m not so unhappy about. It’s like the Everest of voids – there has to be one that’s bigger than the rest," Carlos Frenk, a cosmologist from the University of Durham in the UK, who wasn't involved in the research, told Devlin. "But it doesn’t explain the whole Cold Spot, which we’re still in the dark about."

The one thing the slow-down of light as it passes through the supervoid does support, however, is the fact that the Universe is expanding at an accelerating rate. As Devlin explains:

"This is because the photons convert kinetic energy to gravitational potential as they travel to the heart of the void and get further from denser surrounding patches of universe - think of it as climbing a hill. In a stationary universe, the situation would be symmetrical and so the photons would regain the lost energy on the way out of the void (down the hill) and exit at the same speed.

In an accelerated expansion of the universe, however, everything is effectively becoming less dense as space is stretched out, so voids become relatively shallower over time. This means by the time the light descends the virtual hill, the hill has become flatter and the light cannot pick up all the speed it lost on the way in."

So if you weren't already feeling like the Universe was a cold, lonely place, don't worry, there are now holes out there thousands of times bigger than our entire galaxy.



http://www.sciencealert.c(...)n-light-years-across

quote:

NASA May Have Accidentally Created a Warp Field

_{April 24, 2015 Paul Seaburn}

quote:

To get around the theory of relativity, physicist Miguel Alcubierre came up with the concept of a bubble of spacetime which travels faster than the speed of light while the ship inside of it is stationary. The bubble contracts spacetime in front of the ship and expands it behind it. The warp drive would look like a football inside a flat ring. The tremendous amount of energy it would need made this idea prohibitive until Harold “Sonny” White of NASA’s Johnson Space Center calculated that making the ring into a donut shape would significant reduce the energy needs.

Meanwhile, in the lab, NASA and other space programs were working on prototypes of the EmDrive or RF resonant cavity thruster invented by British aerospace engineer Roger J. Shawyer. This propulsion device uses a magnetron to produce microwaves for thrust, has no moving parts and needs no reaction mass for fuel. In 2014, Johnson Space Center claimed to have developed its own low-power EmDrive.

Which brings us to today’s warp field buzz. Posts on NASASpaceFlight.com, a website devoted to the engineering side of space news, say that NASA has a tool to measure variances in the path-time of light. When lasers were fired through the EmDrive’s resonance chamber, it measured significant variances and, more importantly, found that some of the beams appeared to travel faster than the speed of light. If that’s true, it would mean that the EmDrive is producing a warp field or bubble.

Het artikel is langer.

CHILE'S HUGE VOLCANIC ERUPTION MAKES LIGHTNING, CAN BE SEEN FROM SPACE

Devastatingly beautiful.



FIONA MACDONALD

25 APR 2015

Earlier this week, Chile's Cabulco volcano started erupting for the first time in 43 years, spraying dust and ash at least 15 kilometres into the sky, and causing the evacuation of up to 2,000 local residents.

Thankfully there have been no casualties or serious injuries reported, but the volcano has put on one hell of a show, producing a breathtaking display of volcanic lightning with its second eruption and blasting out red-hot rocks and lava. You can marvel at the power of nature in the incredible time-lapse footage below.


What causes volcanic lightning? As Bec Crew wrote for ScienceAlert last month, this eerily beautiful phenomenon is triggered when giant ash clouds spew out of a volcano's mouth: "As the individual ash particles make contact and rub against each other, they produce enough static electricity to convert into bursts of lightning."

This ash cloud has since caused flight cancellations as it blows across South America, and has produced a plume that can be seen from space. The below infrared image was taken by the Suomi NPP satellite on 23 April.



NASA’s Terra satellite also snapped a natural-colour photo of the ash plume, below:



And there have been no shortage of amazing Earth-bound images across Twitter.

https://twitter.com/LKrauss1

You can see the volcano's initial eruption unfolding below, and follow Indefinitely Wild's coverage for updated footage and photos.

Bron: http://www.sciencealert.c(...)n-be-seen-from-space

Met een muziekje erbij



[ Bericht 5% gewijzigd door Kijkertje op 25-04-2015 23:00:45 ]

ARE SPACE AND TIME AN ILLUSION?

Thanks to this explainer, you no longer have to pretend you understand the concept of spacetime!

28 APR 2015


What exactly is spacetime? Well, it's a mathematical model that combines measurements of both space and time into a single continuum, with space consisting of three dimensions, and time consisting of one dimension - known as the fourth dimension. Simple! Okay, it's really not, but the video above by the PBS Space Time channel is here to explain it all to you in the easiest way possible.

First off, if we can already quantify both space and time, why do we need to combine them into an entirely new measurement? As Gabe Perez-Giz explains in the video above, we need it because we could have two 'observers' of space and time - two different types of particles, for example - and they could both disagree on how much space there is between things at any given point in time.

They could even disagree about the actual sequence of events that have occurred. But as long as their measurements are consistent, neither observer is wrong. Both particles have the correct measurements of space and time, despite coming up with completely different answers.

Put simply, this means that an event in someone's past could be in someone else's future, and there would be nothing 'wrong' about either of their realities. "Any disagreement means that there is no universal division of events in the past, present, and future, which opens major philosophical cans of worms for things like free will, and our belief that we can change the future," says Gabe. "So is everyone's experience of the Universe entirely subjective? If time and space as we usually conceive of them aren't part of objective reality, then what is?"

If you're confused, that's okay, if you're intrigued, good! The video above has the answers you need, and you just might come out of it with a brand new, much clearer understanding of one of the most important concepts in physics (and a thoroughly blown mind). You're welcome.

Bron: http://www.sciencealert.com/watch-are-space-and-time-an-illusion

MATHEMATICIANS DISPUTE CLAIMS THAT THE 'GOLDEN RATIO'IS A NATURAL BLUEPRINT FOR BAUTY


Experts blast 'myth that refuses to go away', saying that sums alone cannot define which faces are easy on the eye

Revered as the formula that defines beauty, the golden ratio is a mathematically derived principle claimed by many to be embodied in objects as diverse as a spiralled seashell and the Parthenon.


But the widespread belief that the golden ratio is the natural blueprint for beauty is pseudo-scientific “hocus-pocus” and a “myth that refuses to go away”, according to leading mathematicians.

The issue has flared up again, after one of the United States’s leading scientific organisations, the Smithsonian, promoted highly contentious claims about the ratio at the National Math Festival in Washington DC earlier this month.


Theories that the Parthenon in Athens, pictured, and Great Pyramid in Egypt were built according to the golden ratio have also been disproved (EPA)

Eve Torrence, a professor at Randolph–Macon College in Virginia, said she was appalled to find a Smithsonian-branded stall which claimed the golden ratio is found in the human body. It offered visitors the chance to put their head through an oval, allegedly to demonstrate whether their face was in accordance with what is also known as the “divine proportion”.

“The idea that there’s this one rectangle [based on the golden ratio] that’s this perfect one... and is reflected in the human body, that’s one of the most silly things. Human beings are so different,” she said.

“There are lots of ratios and proportions in the human body, but they are not all the golden ratio and they are not all precisely the golden ratio. It’s a very loosey-goosey, pseudo-science kind of thing that they are promoting.

“There’s not this number that’s got this perfection in the way people think it does. It feels dirty to mathematicians. It’s hocus-pocus.”

However, there is genuine maths behind the ratio itself. First described by Euclid, it is created by dividing a line into two unequal sections in such a way that the ratio between the whole line and the longer section is the same as the ratio between the longer and shorter sections. This works out at approximately 1.618:1.

The ratio can be used to create different shapes such as a rectangle, triangle or a spiral. The spiral shapes are found in some plants.

But Dr Keith Devlin, a Stanford University mathematician, said Euclid had never claimed the ratio had any aesthetic qualities, an idea largely invented by Gustav Theodor Fechner, a 19th-century German psychologist. More recently it appeared in a 1959 educational cartoon, Donald in Mathmagic Land, and Dan Brown’s The Da Vinci Code.


The ratio can be used to create different shapes such as a rectangle, triangle or a spiral. The spiral shapes are found in some plants (Rex)

Dr Devlin, who campaigns against myths associated with the golden ratio, pointed to “considerable evidence” that people do not find golden rectangles more appealing than others. On the contrary, they tend to favour aspect ratios they are familiar with, such as an A4 piece of paper or a computer screen.

He also said the popular idea that the navel divides the human body in accordance with the golden ratio is false. The figures are close, but there is considerable variation.

Theories that the Parthenon in Athens and Great Pyramid in Egypt were built according to the golden ratio have also been disproved, he said. “The golden ratio stuff is in the realm of religious belief. People will argue it is true because they believe it, but it’s just not fact.”

Such views are dismissed by believers such as Dr Stephen Marquardt, a plastic surgeon and chief executive of Marquardt Beauty Analysis in California, who has patented facial grids derived from the golden ratio to guide surgery.


The golden ratio is a mathematically derived principle but is not present in the spiral of a Nautillus shell (Rex)

Asked about the mathematicians’ objections, he said: “I would say they haven’t done their homework... Mathematicians have their heads up their asses about half the time.”

Dr Marquardt said Marilyn Monroe’s face was “not perfect” but “pretty close”, while Angelina Jolie was “all right [but] her lips are a little large”. The closest fits to golden-ratio defined perfection were Audrey Hepburn and Pierce Brosnan.

The Smithsonian refused to discuss the claims made on its stall.

Bron: http://www.independent.co(...)beauty-10204354.html

THIS NEW METAL BOX COULD HELP TAKE PHYSICS BEYOND THE STANDARD MODEL

Welcome to the weakest magnetic field in the Solar System.


FIONA MACDONALD 14 MAY 2015

Researchers in Germany have created a shield that can cut magnetic fields more than a million-fold, and they've used it to create one of the most exciting metal boxes on the planet right now.

The 4.1-cubic-metre space has the weakest magnetic field in our Solar System, and it will allow scientists to finally conduct the high-precision experiments that could reveal physics beyond the Standard Model.

The Standard Model of particle physics, also known as 'The Theory of Almost Everything', is the best set of equations we have to explain the behaviour and interactions of the fundamental particles in the Universe.

But although the model has served us well, there are a whole lot of gaps, such as the fact that the Standard Model doesn't explain gravity, or why matter and antimatter from the Big Bang didn't annihilate each other completely. It also can't predict the behaviour of particles at very high energies.

Large-scale experiments such as the Large Hadron Collider are helping to improve our understanding in these areas, but are limited by the natural and artificial magnetic fields on Earth, which have the unfortunate habit of easily penetrating all kinds of matter.

But now, researchers from Technische Universität Müchen (TUM) in Germany have managed to eliminate magnetic fields to previously unheard-of levels, opening up a whole new world of experiments. In fact, their box's magnetic field is even weaker than the average ambient magnetic field experienced in the interstellar medium between galaxies.

"Precision experiments are able to probe nature up to energy scales which might not be accessible by current and next generation collider experiments," Tobias Lins, a doctoral student who worked on the magnetic shield, said in a press release. This is because the existence of exotic new particles could be detected by tiny alterations in the properties of already known particles, but we currently can't track those changes because of the background 'noise' from magnetic fields.

The shield, which involves several layers of a specially made, highly magnetic nickel-and-iron alloy, acts like a sponge that absorbs and redirects a magnetic field. The researchers describe its design and performance in the Journal of Applied Physics.

Astrid Eckert/Technische Universität Müchen

"The apparatus might be compared to cuboid Russian nesting dolls," said Lins. "Like the dolls, most layers can be used individually and with an increasing number of layers the inside is more and more protected."

They're already planning to use their shield to determine the charge distribution in neutrons - referred to by physicists as the electric dipole moment. Essentially what they're looking for is the brief moment when a neutron has a tiny magnetic charge - generally a neutron is electrically neutral because its three quarks cancel each other out. If they find that this moment lasts for longer than predicted by the Standard Model, it could suggest the existence of a new particle.

"This kind of measurement would be of fundamental significance in particle physics and swing wide open the door to physics beyond the Standard Model of particle physics," explained the team leader, Peter Fierlinger, in a statement.

The team also wants to use the shield to search for the long-theorised, but never detected, magnetic monopoles using a SQUID detector, which can detect extremely subtle magnetic fields.

Both of these experiments, as well as the many others that can now be conducted inside this small, metal box, could take us into a brave new world of physics, and we can't wait to see some results. We've said it before, and we'll say it again: what an incredible time to be alive.

http://www.sciencealert.c(...)d-the-standard-model

AN ELECTRONIC MEMORY CELL HAS BEEN CREATED THAT MIMICS THE HUMAN BRAIN

Bionic brains are getting closer.

FIONA MACDONAL 18 MAY 2015

Scientists have built a tiny, long-term memory cell that can both store and process information at the same time, just like the human brain. This is one of the first multi-state electronic memory cells, and it represents a crucial step towards building a bionic brain.

Not only does this new cell - which is 10,000 times thinner than a human hair - open up the potential to store and process way more data than ever before, scientists are even more excited about the fact that it has 'memristive' abilities. This means that it's able to retain remember and be influenced by information that has previously been stored on it - something that our current storage devices aren't capable of.

This is the closest we have come to creating a brain-like system with memory that learns and stores analog information and is quick at retrieving this stored information," project leader Sharath Sriram, from RMIT University in Australia said in a press release. "The human brain is an extremely complex analog computer ... its evolution is based on its previous experiences, and up until now this functionality has not been able to be adequately reproduced with digital technology."

The cell's new abilities add another dimension beyond the on/off memory cells we currently use to store our data on conventional devices, such as USBs, which are only capable of storing one binary digit (either a 0 or a 1) at a time. The researchers are comparing this to the difference between a regular light switch, which either turns the light on or off, and a dimmer switch, which gives you access to all the shades of light in-between.

"It can give you much more flexibility in terms of what information you store and what functionality you get," one of the researchers, Hussein Nili, told Jessica Kidd over at ABC News.

Publishing in Advanced Functional Materials, the researchers explain that the cells are made out of a functional oxide material in the form of an ultra-thin film. The team created the material last year, and demonstrated that it was highly stable and reliable. But they've now successfully introduced controlled defects into the film, which allow the cell to be influenced by previous events.

"We have now introduced controlled faults or defects in the oxide material along with the addition of metallic atoms, which unleashes the full potential of the 'memristive' effect - where the memory element's behaviour is dependent on its past experiences," Nili explained in the release.

All this means that the cells could one day be used to build an artificial system that mimics the extraordinary abilities of the human brain, which is extremely fast, requires very little energy input, and has almost limitless memory storage. While the benefits to artificial intelligence and computing are obvious, such a 'bionic brain' could also greatly help human health by allowing researchers to create and study diseases such as Alzheimer's and Parkinson's outside of the body.

"In terms of those diseases, there are two problems: it is very hard to read what is going on inside a live brain, and the ethical aspect - you cannot experiment on live subjects without repercussions," Nili told Ariel Bogle from Mashable. "If you can have a bionic brain and you can replicate those kinds of [diseased] brains ... it will make research much easier and accessible."

We're pretty excited to see what these little cells can do.

http://www.sciencealert.c(...)mics-the-human-brain

IMAGES OF SUPERNOVAE MINUTES AFTER IGNITION CHALLENGES MAIN THEORY OF FORMATION

They can occur, it seems, when stars collide.

MYLES GOUGH 22 MAY 2015

An international team of scientists has captured the earliest images of supernovae in action - only minutes after ignition - and they say these massive stellar explosions are occurring after stars collide, challenging theories that supernova occur in a uniform way.

A supernova is a stellar explosion that can briefly outshine an entire galaxy, comprised of billions of stars. Using the Kepler space telescope, researchers photographed three of these cosmic events between 600 and 1.8 billion light-years from Earth.

They were looking specifically at type Ia supernovae, which involve the explosive deaths of ageing white dwarf stars that exist in a binary orbit with a sister star.

"We were able to capture the supernovae in the first minutes of the explosion, the earliest previously had been two-and-a-half hours after the event," astrophysicist and team member Brad Tucker, from the Australian National University, told Stuart Gary at ABC Science.

The team tracked the explosions in detail until they reached their pinnacle of brightness three weeks later, and then monitored the subsequent declines, as their light signatures faded away over the next few months.

They found that the initial stages of their supernovae didn't fit very well with prevailing theories about how they occur.

"The stars all blow up uniquely. It doesn't make sense," Tucker said in a press release. "It's particularly weird for these supernovae because even though their initial shockwaves are very different, they end up doing the same thing."

Before their study offered an unprecedented glimpse into the early stages of this stellar phenomena, astronomers only had information about what was happening in type Ia supernovae 2.5 hours after the star's explosive dying process had commenced.

What they observed was that after this 2.5-hour mark, the dying stars all followed an identical pattern. This led to theories that they might also originate in identical ways.

The prevailing theory has been that these explosions occur when the compact white dwarf - or the dying star - uses its gravity to pull hot material from its companion star onto its surface. Eventually, the added heat and pressure causes the star's core to explode.

But the team found no evidence of the supernovae ejecta interacting with a companion star, as might be expected.

"Somewhat to our surprise the results suggest an alternative hypothesis, that a violent collision between two smallish white dwarf stars sets off the explosion," lead researcher Robert Olling from the University of Maryland in the US, said in a press release.

The team's results, which were recently published in Nature, provide new insight into how some of these explosions form and could help astronomers use their light signatures to more accurately gauge cosmic distances between galaxies.

But it doesn't cancel out the other formation theory: a second paper published in the same issue of Nature by a different team has found evidence to support the view that these events can still be triggered by stars accreting matter from their companions.

The team from the California Institute of Technology used NASA's Swift space telescope to study a supernova 300-million-light-years away. They found that as the ejected material expanded outwards it eventually collided with the companion star. They say this provides evidence that the explosion is resulting from a single degenerating star, rather than a collision.

"As the blast wave hits the companion star it interacts with it and generates ultraviolet emissions which we detected with Swift," lead author and graduate student, Yi Cao, told ABC Science.

"We realised that this was probably the supernova companion interaction and we were very excited because we have been searching for this signal for a while."


http://www.sciencealert.c(...)-theory-of-formation

http://www.abc.net.au/science/articles/2015/05/21/4239232.htm



[ Bericht 5% gewijzigd door Kijkertje op 22-05-2015 15:34:29 ]

AMPUTEES CAN NOW CONTROL BIONIC LEGS WITH THEIR MIND

The future looks so good.


BEC CREW 21 MAY 2015

Scientists in Iceland have invented new bionic prosthetic limbs that can be controlled by a person’s thoughts alone, and they’re so good, two patients are already trialling the technology.

Developed by a company called Ossur, the world-first technology involves surgically implanting 5 mm by 3 mm myoelectric sensors (IMES) into a person’s residual muscle tissue to measure and interpret the signals travelling between its nerve-endings and the brain. Leg movement is triggered by a connected receiver, and the process is so streamlined, it allows a patient to perform actions subconsciously.

"The brain power, when it takes over, actually gives impulses through the brain into the muscles, then the muscles contract," orthopaedic surgeon and director of research and development at Ossur, Thorvaldur Ingvarsson, told Amy Pollack at Reuters. "We put sensors into the muscles, and the muscles would pick up the signals, and the signals move their way into the prosthetics, and then the prosthetics react as your brain wants."

The technology differs from similar mind-controlled prosthetics because it doesn’t require muscle tissue to be transplanted from another part of the body into the affected area, says Pollock. This requires an intense amount of mental training by the patient, because their brain has to get used to their muscle tissue functioning in a completely different region of the body.

One of the two amputees who has been trialling the bionic legs for the past 12 months, Gummi Olafsson, described to Pollock the bizarre feeling of controlling a piece of technology like it was a natural part of his body:

"As soon as I put my foot on, it took me about 10 minutes to get control of it. I could stand up and just walk away. Come back, sit down, use my muscles to move my foot in the position I wanted to use it. It was like you couldn't believe the feeling when you were moving your ankle. It was really strange. I couldn't explain it. It was like, I was moving it with my muscles, there was nobody else doing it, the foot was not doing it, I was doing it, so it was really strange and overwhelming."

Olafsson added that practice is everything when it comes to figuring out how to better manipulate the bionic legs, and is now working on diversifying his skills to get him uphill, downhill, upstairs, downstairs, and sitting and standing on a chair.

And what’s really awesome about this technology is that it's compatible with current bionic legs that amputees around the world have already gotten used to. Patients will now be able to upgrade their existing prosthetics, which have already been adapted to their individual walking style, with the capacity for mind-control.

Ingvarsson says that the next step for the technology might be to embed a network of sensors into the prosthetic limbs to create a feedback loop about what’s going on in the surrounding environment, similar to how sensors in driverless cars create an impression of the pathways and obstacles around them.

Watch the technology being tested here:


http://www.sciencealert.c(...)legs-with-their-mind

OCTOPUSES AND THEIR RELATIVES SENSE LIGHT THROUGH SKIN

Sensors in their skin detect changes in the colour of light, and in response the animals change colour to camouflage themselves

Whether it's a dull sandy seabed or a multi-coloured coral reef, octopuses change the colour of their skin to blend in perfectly with their environment. It now seems their skin is not just obeying instructions from the octopus's brain: it also has local sensors that can perceive light and trigger a colour change.

Soft-bodied cephalopods like octopuses, squid and cuttlefish rely on camouflage to escape from predators. In the highly colourful undersea world, this means constantly changing their skin to match the environment.

Their eyes perceive the surroundings, then the brain processes the information and sends signals directly to the skin, causing dramatic changes of colour and pattern in a matter of milliseconds.

But it's not just the brain that controls the skin patterning, according to two studies in the Journal of Experimental Biology.


A California two-spot octopus (Octopus bimaculoides) (Credit: Visuals Unlimited/NPL)

Desmond Ramirez and Todd Oakley of the University of California Santa Barbara cut out bits of skin from California two-spot octopuses and kept them in their lab. They found that even though the piece of skin was not "alive" and connected to an octopus, it could still respond to light.

Octopus skin is covered with specialised pigmented organs called chromatophores, which are basically tiny bags filled with coloured chemicals. If the muscles around the chromatophore contract, the bag gets stretched out, revealing the colour.

When Ramirez exposed the biopsied skin to white light, the chromatophores expanded significantly: five-fold in adult skins and two-fold in hatchling skins.

The response was slower than in whole octopuses. Once they were exposed to white light, adult chromatophores took about 6s to start responding, and another 5s to expand fully. "In whole animals, the changes in the chromatophores happen much more quickly," says Ramirez.


A broadclub cuttlefish (Sepia latimanus) (Credit: Inaki Relanzon/NPL)

Animals have specialised proteins called opsins that respond to light. He and Oakley found that the genes coding for opsins were activated in the octopus skin.

It was the same type of opsin found in the octopus eye, contained in sensory neurons that were packed into the entire surface of each octopus's mantle, head and arms.

The same seems to be true of other cephalopods, according to a second study in the same journal by Thomas Cronin of the University of Maryland Baltimore County and his colleagues.


A pair of common cuttlefish (Sepia officinalis) (Credit: Alex Mustard/NPL)

Working with two cuttlefish and a squid, the group was able to show that all the proteins involved in light detection in the cephalopods' eyes were also found in the skin -- specifically, inside their chromatophores.

The findings suggest that cephalopods have two ways of controlling their skin colour. One is central, driven by the brain, and the other is spread throughout their skin.

"What we do not yet know is how these two inputs come together to control chromatophores in the whole animal," says Ramirez.



http://www.bbc.com/earth/(...)-see-with-their-skin

NASH'S MIND LEFT A BEAUTIFUL LEGACY

Death of game theory pioneer ends a genius’s dramatic story

by Tom Siegfried 3:50pm, May 24, 2015


Mathematician John Nash died in a car accident May 23 at the age of 86, ending a dramatic story of genius.

His mind was beautiful, but troubled. His math was just beautiful.

John Forbes Nash Jr., who died in a traffic accident on May 23, gained more fame than most mathematicians, though not only on account of his math. His battle with schizophrenia, described artfully by Sylvia Nasar in her book A Beautiful Mind, made for drama suitable for a movie. Russell Crowe played Nash in the 2001 film, which garbled the math but made the point that despite his affliction, Nash accomplished works of genius — particularly in the theory of games.

That genius emerged in the 1940s when Nash was an undergraduate at Carnegie Tech, the forerunner to Carnegie Mellon University, in Pittsburgh. He started out as an electrical engineering student, but soon shifted to chemical engineering and then just plain chemistry. But the lab was not for him. He switched to math, and by age 20 he was on his way to graduate school at Princeton with a one-sentence letter of recommendation from a Carnegie professor: “This man is a genius.”

At Princeton, Nash revolutionized economic theory, showing how the freshly developed game theory of the great John von Neumann and Oskar Morgenstern could be made more relevant to real life. In their book, Theory of Games and Economic Behavior, von Neumann and Morgenstern had attempted to derive a mathematics of strategy. They showed how participants in an economy could choose the most profitable behaviors. Von Neumann, one of the foremost mathematicians of his time, and Morgenstern, an economist, realized that their math could be applied to human behavior more broadly, evaluating strategic choices in realms from poker to warfare.

But the original theory offered rigorous solutions only for two-person games where the winner won what the loser lost (hence the label “zero-sum” game). Nash extended game theory both to cooperative situations (where win-win scenarios were possible) and to competitive games with multiple players.

Out of this work came the concept of the “Nash equilibrium,” the set of strategies that guaranteed the best possible payoff for all participants. Nash’s genius was to prove that at least one such set of strategies was always possible. In other words, as the economist Samuel Bowles once put it, there is always “a situation in which everybody is doing the best they can, given what everybody else is doing.”

In such situations, “equilibrium” means that as long as everybody else maintains the same strategy, anybody changing strategies would suffer a worse outcome. So equilibrium describes a stable situation, in which nobody has any incentive to change strategies.

Nash’s equilibrium became the bedrock upon which game theory’s future was built. “The concept of the Nash equilibrium is probably the single most fundamental concept in game theory,” Bowles said. And the economist Roger Myerson called it “one of the outstanding intellectual advances of the 20th century … comparable to that of the discovery of the DNA double helix.”

One of the deepest insights stemming from game theory is the notion that rarely is it wise to stick to a single strategy. In any but the simplest situations, Nash equilibrium is achieved only when players pursue a “mixed strategy.” In other words, a behavior is chosen from a probability distribution — a mix — of different specific strategies. In poker, for instance, a smart player with a losing hand sometimes bluffs and sometimes folds; game theory’s probability distribution tells you what percentage of the time to choose each strategy. This concept of mixed strategies explains all sorts of things about the natural world, from why ecosystems contain so many different species to why some people are cooperators while others are selfish.

Nash made other significant contributions to mathematics in the 1950s, but the dark specter of schizophrenia removed his mind from active engagement in the intellectual world for decades. But eventually his symptoms subsided. And then he was awarded the economics Nobel Prize in 1994, leading to the recognition of his work in both the book and movie A Beautiful Mind.

My own book on game theory emphasized the intellectual fallout from Nash’s math in fields other than economics. His methods were adopted, or adapted, in fields ranging from international diplomacy to evolutionary biology. Today it is widely acknowledged that game theory provides a common mathematical language for analyzing research across the entire spectrum of the social sciences. Game theory provides a method for quantifying human behavior, even though humans don’t always behave in the way a naïve application of game theory would suggest.

Game theory’s reach has extended beyond social sciences and biology. The probabilities involved in computing mixed game theory strategies are similar to those in other fields, such as statistical physics, information theory and even quantum mechanics, in the form of quantum game theory.

Nash, in fact, derived his notion of equilibrium in the first place from an analogy to physical science. When he studied chemistry, he encountered the law of mass action, the math describing how chemical reactions reach equilibrium. It’s a purely physical process of course, governed by the laws of thermodynamics, which drive natural systems to a state of energetic stability. Nash showed how a thoroughly analogous process, governed by the math of game theory, can drive economic or other social systems to a state of stability.

As I wrote recently, there are indications that game theory could prove useful in solving mysteries ranging from how to cure cancer to the origin of life. Perhaps game theory generally, and the Nash equilibrium in particular, captures something about relationships in the world that goes deeper than mere analogy. If so, that would be beautiful.

https://www.sciencenews.o(...)utiful-legacy?tgt=nr

UNCOMFORTABLY NUMB: THE PEOPLE WHO FEEL NO PAIN.

Researchers have identified a third gene that causes congenital insensitivity to pain when mutated


Dental syringe and lignocaine ampules. Photograph: Wellcome Images

Being unable to feel pain may sound appealing, but it would be extremely hazardous to your health. Pain is, for most of us, a very unpleasant feeling, but it serves the important evolutionary purpose of alerting us to potentially life-threatening injuries. Without it, people are more prone to hurting themselves and so, because they can be completely oblivious to serious injuries, a life without pain is often cut short.

Take 16-year-old Ashlyn Blocker from Patterson, Georgia, who has been completely unable to sense any kind of physical pain since the day she was born. As a newborn, she barely made a sound, and when her milk teeth started coming out, she nearly chewed off part of her tongue. Growing up, she burnt the skin off the palm of her hands on a pressure washer that her father had left running, and once ran around on a broken ankle for two whole days before her parents noticed the injury. She was once swarmed and bitten by hundreds of fire ants, has dipped her hands into boiling water, and injured herself in countless other ways, without ever feeling a thing.

Ashlyn is one of a tiny number of people with congenital insensitivity to pain. The condition is so rare, in fact, that the doctor who diagnosed her in 2006 told her parents that she may be the only one in the world who has it. But later that year, a research team led by Geoffrey Woods of the University of Cambridge, identified three distinct mutations in the SCN9A gene, all of which cause the same condition in members of three large families in northern Pakistan, and in 2013, Ashlyn’s doctor Roland Staud and his colleagues reported that her condition is the result of two other mutations in the same gene.

Now, Woods and his colleagues have discovered yet more mutations that cause congenital insensitivity to pain. They studied 11 families form around the world, and identified within them 158 individuals, all of whom suffer from either congenital pain insensitivity or hereditary sensory and autonomic neuropathy, another rare condition that also causes loss of pain sensation by damaging the nerves that carry pain signals up the spinal cord and then into the brain.

Using state-of-the-art DNA sequencing techniques, the researchers analysed and compared their genomes, and identified no less than 10 different mutations that cause congenital insensitivity to pain, all within a gene called PRDM12, located on the long arm of chromosome 9.

Individuals carrying two defective copies of this gene produce a non-functional PRDM12 protein, and as a result of this have been unable to feel any kind of physical pain, or to distinguish between painfully hot and cold temperatures, from birth. Most of them have experienced numerous, painless injuries. As infants and young children, they bit their fingers, toes, and lips so often that they are severely mutilated, and hurt themselves many times and in many other ways. The worst affected have suffered repeated infections while growing up, injuries that scarred their skin and deformed their bones.

PRDM12 is the third human gene to be associated with congenital insensitivity to pain. SCN9A was the first such gene to be discovered, and we now know of at least 13 different mutations in it, all of which cause congenital insensitivity to pain. In 2013, another research team reported that they had identified a mutation in a related gene, called SCN11A, which also causes the condition. SCN9A and SCN11A encode sodium channel proteins that pain-sensing fibres need to generate nervous impulses.

Mutations in SCN9A produce a non-functional sodium channel, so that pain fibres can still detect painful stimuli but are unable to send signals about them to the brain. The SCN11A mutation produces over-active sodium channels that interfere with the pain fibres’ ability to produce and send their impulses.

The PRDM12 mutations cause pain insensitivity another way. When Woods and his colleagues examined biopsies from several of the affected people they studied, they found that the skin in their legs contains no nerve endings whatsoever, and that one of the sensory nerves in their legs contains about half the normal number of pain-sensing fibres. This led them to speculate that PRDM12 plays an important role in the development of pain-sensing neurons and their fibres.

Exploring further, they examined the distribution of PRDM12 in developing mouse embryos, and in pain neurons generated from human stem cells. This revealed that the protein is synthesized at the exact time when pain neurons are forming, and in exactly the right places – in the region where immature pain neurons are first created, along the migration route they take before maturing, and in the dorsal root ganglia and superficial layers of the spinal cord, where their cell bodies and fibres end up, respectively.

The researchers then reduced the amount of PRDM12 protein synthesized by developing frog embryos, and found that this significantly altered the distribution of pain nerves. The PRDM12 protein is a transcription factor, or a “master control gene” that regulates the activity of dozens of other developmental genes. Woods and his colleagues performed one final set of experiments which suggest that it does so by means of epigenetic modifications that switch these genes on or off by altering chromosome structure.

These results confirm that PDRM12 is essential for the development of pain-sensing neurons, and neatly explain why it causes pain insensitivity when mutated. Whereas people with a mutation in SCN9A or SCN11A have pain fibres that don’t send signals, those carrying a PDRM12 mutation fail to develop pain fibres altogether.

Pain is a major global health problem that affects a significant proportion of the world’s population, and has an estimated annual cost of at least $560 billion in the U.S. alone. Management of chronic pain – defined as any pain lasting longer than 3 months – can be especially difficult, as it often presents itself with no underlying physical cause.

These new findings open up promising avenues for understanding pain, and suggests that it may be possible to develop new analgesics that target PRDM12 and provide relief by epigenetic “reprogramming” of over-active pain neurons.

http://www.theguardian.co(...)ple-who-feel-no-pain

HUMANS WILL BE CYBORGS WITHIN 200 YEARS, EXPERT PREDICTS

“It will be the greatest evolution in biology since the appearance of life.”

FIONA MACDONALD 29 MAY 2015

Within the next 200 years, humans will have become so merged with technology that we’ll have evolved into “God-like cyborgs”, according to Yuval Noah Harari, an historian and author from the Hebrew University of Jerusalem in Israel.

Harari researches the history of the human species, and after writing a new book on our past, he now believes that we’re just a few short centuries away from being able to use technology to avoid death altogether - if we can afford it, that is.

“I think it is likely in the next 200 years or so Homo sapiens will upgrade themselves into some idea of a divine being, either through biological manipulation or genetic engineering of by the creation of cyborgs: part organic, part non-organic,” Harari said during his presentation the Hay Festival in the UK, as Sarah Knapton reports for the Telegraph. “It will be the greatest evolution in biology since the appearance of life … we will be as different from today’s humans as chimps are now from us.”

Obviously, we should take Harari’s predictions with a grain of salt, but while they sound more suited to science fiction than real life, they're not actually that out-there. Many researchers believe that we’ve already started down the path towards a cyborg future; after all, many of us already rely on bionic ears and eyes, insulin pump technology and prosthetics to help us survive. And with researchers recently learning how to send people’s thoughts across the web, subconsciously control bionic limbs and use liquid metal to heal severed nerves, it’s not hard to imagine how we could continue to use technology to supplement our vulnerable human bodies further.

Interestingly, Harare’s comments came just a few days after UK-based neuroscientist Hannah Critchlow from Cambridge University got the Internet excited by saying that it could be possible to upload our brains into computers, if we could build computers with 100 trillion circuit connections. “People could probably live inside a machine. Potentially, I think it is definitely a possibility,” Critchlow said during her presentation at the festival.

But Harari warned that these upgrades may only be available to the wealthiest members of society, and that could cause a growing biological divide between rich and poor - especially if some of us can afford to pay for the privilege of living forever while the rest of the species dies out.

If that sounds depressing, the alternative is a future where instead of us taking advantage of technology, technology takes advantage of us, and artificial intelligence poses a threat to our survival, as Elon Musk, Stephen Hawking, and Bill Gates have all predicted.

Either way, one thing seems pretty clear - our future as a species is now inextricably linked with the technology we've created. For better or for worse.


http://www.sciencealert.c(...)ears-expert-predicts

WATCH: THE ARCHER'S PARADOX IN SLOW MOTION

Because arrows don't actually fly straight.

FIONA MACDONALD 29 MAY 2015


If you're anything like me, you probably think that an arrow shoots pretty straight - hence the saying 'straight as an arrow', right? But it turns out, that's not the case at all, as Destin reveals so spectacularly in the latest episode of Smarter Every Day, where he sets out to uncover the physics behind the Archer's Paradox.

So what is this paradox? In order to shoot an arrow, you need to place it either to the right or left of your bow. But in order to hit your target, you need your arrow to fly in a straight line. So somehow archers manage to curve their arrows around that obstacle in order to hit their target... and as Destin proved in another recent episode, archers are able to hit some incredibly tiny targets.

To figure it out, Destin sets up his Phantom slow-motion camera, and experiments with a range of different bows. What he finds is that the solution to this paradox all comes down to the arrow, which actually isn't rigid at all. In fact, it not only bends once to get around the bow, once it's released, it curves the whole way to the target, creating a wave pattern complete with nodal points through the air, which keeps it on a straight path.

But how do archers know how their arrow's spine is going to curve in order to have such incredible accuracy? That's actually a pretty cool process, which requires some serious science. Watch the episode above to find out, and fully appreciate how talented archers really are.

http://www.sciencealert.c(...)radox-in-slow-motion

THE STRANGE FATE OF A PERSON FALLING INTO A BLACK HOLE

If you fell into a black hole, you might expect to die instantly. But in fact your fate would be far stranger than that

It could happen to anyone. Maybe you're out trying to find a new habitable planet for the human race, or maybe you're just on a long walk and you slip. Whatever the circumstances, at some point we all find ourselves confronted with the age-old question: what happens when you fall into a black hole?

You might expect to get crushed, or maybe torn to pieces. But the reality is stranger than that.

The instant you entered the black hole, reality would split in two. In one, you would be instantly incinerated, and in the other you would plunge on into the black hole utterly unharmed.


Heavy objects warp the fabric of space itself (Credit: Julian Baum/SPL)

A black hole is a place where the laws of physics as we know them break down. Einstein taught us that gravity warps space itself, causing it to curve. So given a dense enough object, space-time can become so warped that it twists in on itself, burrowing a hole through the very fabric of reality.

A massive star that has run out of fuel can produce the kind of extreme density needed to create such a mangled bit of world. As it buckles under its own weight and collapses inward, space-time caves in with it. The gravitational field becomes so strong that not even light can escape, rendering the region where the star used to be profoundly dark: a black hole.

The outermost boundary of the hole is its event horizon, the point at which the gravitational force precisely counteracts the light's efforts to escape it. Go closer than this, and there's no escape.

The event horizon is ablaze with energy. Quantum effects at the edge create streams of hot particles that radiate back out into the universe. This is called Hawking radiation, after the physicist Stephen Hawking, who predicted it. Given enough time, the black hole will radiate away its mass, and vanish.

As you go deeper into the black hole, space becomes ever more curvy until, at the centre, it becomes infinitely curved. This is the singularity. Space and time cease to be meaningful ideas, and the laws of physics as we know them — all of which require space and time — no longer apply.

What happens here, no one knows. Another universe? Oblivion? The back of a bookcase? It's a mystery.


In a black hole, space becomes infinitely curved (Credit: Henning Dalhoff/SPL)

So what happens if you accidentally fall into one of these cosmic aberrations? Let's start by asking your space companion — we'll call her Anne — who watches in horror as you plunge toward the black hole, while she remains safely outside. From where she's floating, things are about to get weird.

As you accelerate toward the event horizon, Anne sees you stretch and contort, as if she were viewing you through a giant magnifying glass. What's more, the closer you get to the horizon the more you appear to move in slow motion.

You can't shout to her, as there's no air in space, but you might try flashing her a Morse message with the light on your iPhone (there's an app for that). However, your words reach her ever more slowly, the light waves stretching to increasingly lower and redder frequencies: "Alright, a l r i g h t, a l r i…"

When you reach the horizon, Anne sees you freeze, like someone has hit the pause button. You remain plastered there, motionless, stretched across the surface of the horizon as a growing heat begins to engulf you.

According to Anne, you are slowly obliterated by the stretching of space, the stopping of time and the fires of Hawking radiation. Before you ever cross over into the black hole's darkness, you're reduced to ash.

But before we plan your funeral, let's forget about Anne and view this gruesome scene from your point of view. Now, something even stranger happens: nothing.


The boundary of a black hole might be a blazing firewall (Credit: Equinox Graphics/SPL)

You sail straight into nature's most ominous destination without so much as a bump or a jiggle – and certainly no stretching, slowing or scalding radiation. That's because you're in freefall, and therefore you feel no gravity: something Einstein called his "happiest thought".

After all, the event horizon is not like a brick wall floating in space. It's an artefact of perspective. An observer who remains outside the black hole can't see through it, but that's not your problem. As far as you're concerned there is no horizon.

Sure, if the black hole were smaller you'd have a problem. The force of gravity would be much stronger at your feet than at your head, stretching you out like a piece of spaghetti. But lucky for you this is a big one, millions of times more massive than our Sun, so the forces that might spaghettify you are feeble enough to be ignored.

In fact, in a big enough black hole, you could live out the rest of your life pretty normally before dying at the singularity.


The event horizon is not a solid barrier (Credit: Richard Kail/SPL)

How normal could it really be, you might wonder, given that you're being sucked toward a rupture in the space-time continuum, pulled along against your will, unable to head back the other way?

But when you think about it, we all know that feeling, not from our experience with space but with time. Time only goes forwards, never backwards, and it pulls us along against our will, preventing us from turning around.

This isn't just an analogy. Black holes warp space and time to such an extreme that inside the black hole's horizon, space and time actually swap roles. In a sense, it really is time that pulls you in toward the singularity. You can't turn around and escape the black hole, any more than you can turn around and travel back to the past.

At this point you might want to stop and ask yourself a pressing question: What the hell is wrong with Anne? If you're chilling inside the black hole, surrounded by nothing weirder than empty space, why is she insisting that you've been burned to a crisp by radiation outside the horizon? Is she hallucinating?


"Hawking radiation" flows out of the event horizon (Credit: Richard Kail/SPL)

Actually, Anne is being perfectly reasonable. From her point of view, you really have been burned to a crisp at the horizon. It's not an illusion. She could even collect your ashes and send them back to your loved ones.

In fact, the laws of nature require that you remain outside the black hole as seen from Anne's perspective. That's because quantum physics demands that information can never be lost. Every bit of information that accounts for your existence has to stay on the outside of the horizon, lest Anne's laws of physics be broken.

On the other hand, the laws of physics also require that you sail through the horizon without encountering hot particles or anything out of the ordinary. Otherwise you'd be in violation of Einstein's happiest thought, and his theory of general relativity.

So the laws of physics require that you be both outside the black hole in a pile of ashes and inside the black hole alive and well. Last but not least, there's a third law of physics that says information can't be cloned. You have to be in two places, but there can only be one copy of you.

Somehow, the laws of physics point us towards a conclusion that seems rather nonsensical. Physicists call this infuriating conundrum the black hole information paradox. Luckily, in the 1990s they found a way to resolve it.


Once you fall in, there's no coming out (Credit: Science Photo Library)

Leonard Susskind realized that there is no paradox, because no one person ever sees your clone. Anne only sees one copy of you. You only see one copy of you. You and Anne can never compare notes. And there's no third observer who can see both inside and outside a black hole simultaneously. So, no laws of physics are broken.

Unless, that is, you demand to know which story is really true. Are you really dead or are you really alive?

The great secret that black holes have revealed to us is that there is no really. Reality depends on whom you ask. There's Anne's really and there's your really. End of story.

Well, almost. In the summer of 2012, the physicists Ahmed Almheiri, Donald Marolf, Joe Polchinski and James Sully, collectively known as AMPS, devised a thought experiment that threatened to upend everything we thought we knew about black holes.


Nobody is sure what lies inside a black hole (Credit: Henning Dalhoff/SPL)

They realized that Susskind's solution hinged on the fact that any disagreement between you and Anne is mediated by the event horizon. It didn't matter if Anne saw the unlucky version of you scattered amongst the Hawking radiation, because the horizon prevented her from seeing the other version of you floating along inside the black hole.

But what if there was a way for her to find out what was on the other side of the horizon, without actually crossing it?

Ordinary relativity would say that's a no-no, but quantum mechanics makes the rules a little fuzzier. Anne might sneak a peek behind the horizon, using a little trick that Einstein called "spooky action-at-a-distance".

This happens when two sets of particles that are separated in space are mysteriously "entangled". They are part of a single, indivisible whole, so that the information needed to describe them can't be found in either set alone, but in the spooky links between them.


Widely-separated particles can be spookily "entangled" (Credit: Victor de Schwanberg/SPL)

The AMPS idea went something like this. Let's say Anne grabs hold of a bit of information near the horizon — call it A.

If her story is right, and you are a goner, scrambled amongst the Hawking radiation outside the black hole, then A must be entangled with another bit of information, B, which is also part of the hot cloud of radiation.

On the other hand, if your story is the true one, and you're alive and well on the other side of the event horizon, then A must be entangled with a different bit of information, C, which is somewhere inside the black hole.

Here's the kicker: each bit of information can only be entangled once. That means A can only be entangled with B or with C, not with both.


Black holes can pull material away from nearby stars (Credit: NASA/CXC/M. Weiss)

So Anne takes her bit, A, and puts it through her handy entanglement-decoding machine, which spits out an answer: either B or C.

If the answer turns out to be C, then your story wins, but the laws of quantum mechanics are broken. If A is entangled with C, which is deep inside the black hole, then that piece of information is lost to Anne forever. That breaks the quantum law that information can never be lost.

That leaves B. If Anne's decoding machine finds that A is entangled with B, then Anne wins, and general relativity loses. If A is entangled with B, then Anne's story is the one true story, which means you really wereburned to a crisp. Instead of sailing straight through the horizon, as relativity says you should, you hit a burning firewall.

So we're back where we started: what happens when you fall into a black hole? Do you glide right through and live a normal life, thanks to a reality that's strangely observer-dependent? Or do you approach the black hole's horizon only to collide with a deadly firewall?


Black holes distort passing light rays, causing "lensing" (Credit: Ute Kraus, CC by 2.5)

No one knows the answer, and it's become one of the most contentious questions in fundamental physics.

Physicists have spent more than a century trying to reconcile general relativity with quantum mechanics, knowing that eventually one or the other was going to have to give. The solution to the firewall paradox should tell us which, and point the way to an even deeper theory of the universe.

One clue might lie in Anne's decoding machine. Figuring out which other bit of information A is entangled with is an extraordinarily complicated problem. So physicists Daniel Harlow of Princeton University in New Jersey and Patrick Hayden, now at Stanford University in California, wondered how long it would take.

In 2013 they calculated that, even given the fastest computer that the laws of physics would allow, it would take Anne an extraordinarily long time to decode the entanglement. By the time she had an answer, the black hole would have long evaporated, disappearing from the universe and taking with it the threat of a deadly firewall.


Centaurus A has a black hole (Credit: ESO/WFI/MPIfR/APEX/A. Weiss/NASA/CXC/CfA/R. Kraft)

If that's the case, the sheer complexity of the problem could prevent Anne from ever figuring out which story is the real one. That would leave both stories simultaneously true, reality intriguingly observer-dependent, all the laws of physics intact, and no one in danger of running into an inexplicable wall of fire.

It also gives physicists something new to think about: the tantalizing connections between complex calculations (like the one Anne apparently can't do) and space-time. This may open the door to something deeper still.

That's the thing about black holes. They're not just annoying obstacles for space travellers. They're also theoretical laboratories that take the subtlest quirks in the laws of physics, then amplify them to such proportions that they can't be ignored.

If the true nature of reality lies hidden somewhere, the best place to look is a black hole. It's probably best to look from the outside, though: at least until they figure out this whole firewall thing. Or send Anne in. It's her turn already.

http://www.bbc.com/earth/(...)hole-would-clone-you



[ Bericht 0% gewijzigd door Kijkertje op 31-05-2015 18:11:00 ]

REALITY DOESN'T EXIST UNTIL WE MEASURE IT, QUANTUM EXPERIMENT CONFIRMS

Mind = blown.


FIONA MACDONALD 1 JUN 2015

Australian scientists have recreated a famous experiment and confirmed quantum physics's bizarre predictions about the nature of reality, by proving that reality doesn't actually exist until we measure it - at least, not on the very small scale.

That all sounds a little mind-meltingly complex, but the experiment poses a pretty simple question: if you have an object that can either act like a particle or a wave, at what point does that object 'decide'?

Our general logic would assume that the object is either wave-like or particle-like by its very nature, and our measurements will have nothing to do with the answer. But quantum theory predicts that the result all depends on how the object is measured at the end of its journey. And that's exactly what a team from the Australian National University has now found.

"It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it," lead researcher and physicist Andrew Truscott said in a press release.

Known as John Wheeler's delayed-choice thought experiment, the experiment was first proposed back in 1978 using light beams bounced by mirrors, but back then, the technology needed was pretty much impossible. Now, almost 40 years later, the Australian team has managed to recreate the experiment using helium atoms scattered by laser light.

"Quantum physics predictions about interference seem odd enough when applied to light, which seems more like a wave, but to have done the experiment with atoms, which are complicated things that have mass and interact with electric fields and so on, adds to the weirdness," said Roman Khakimov, a PhD student who worked on the experiment.

To successfully recreate the experiment, the team trapped a bunch of helium atoms in a suspended state known as a Bose-Einstein condensate, and then ejected them all until there was only a single atom left.

This chosen atom was then dropped through a pair of laser beams, which made a grating pattern that acted as a crossroads that would scatter the path of the atom, much like a solid grating would scatter light.

They then randomly added a second grating that recombined the paths, but only after the atom had already passed the first grating.

When this second grating was added, it led to constructive or destructive interference, which is what you'd expect if the atom had travelled both paths, like a wave would. But when the second grating was added, no interference was observed, as if the atom chose only one path.

The fact that this second grating was only added after the atom passed through the first crossroads suggests that the atom hadn't yet determined its nature before being measured a second time.

So if you believe that the atom did take a particular path or paths at the first crossroad, this means that a future measurement was affecting the atom's path, explained Truscott. "The atoms did not travel from A to B. It was only when they were measured at the end of the journey that their wave-like or particle-like behaviour was brought into existence," he said.

Although this all sounds incredibly weird, it's actually just a validation for the quantum theory that already governs the world of the very small. Using this theory, we've managed to develop things like LEDs, lasers and computer chips, but up until now, it's been hard to confirm that it actually works with a lovely, pure demonstration such as this one.

The full results have been published in Nature Physics.

http://www.sciencealert.c(...)-experiment-confirms

HOW WILL THE UNIVERSE END, AND COULD ANYTHING SURVIVE?

Science has outlined four ways that our universe could meet its doom. They're called the Big Freeze, the Big Crunch, the Big Change and the Big Rip

Don't panic, but our planet is doomed. It's just going to take a while. Roughly 6 billion years from now, the Earth will probably be vaporized when the dying Sun expands into a red giant and engulfs our planet.

But the Earth is just one planet in the solar system, the Sun is just one of hundreds of billions of stars in the galaxy, and there are hundreds of billions of galaxies in the observable universe. What's in store for all of that? How does the universe end?

The science is much less settled on how that will happen. We're not even sure if the universe will come to a firm, defined end, or just slowly tail off. Our best understanding of physics suggests there are several options for the universal apocalypse. It also offers some hints on how we might, just maybe, survive it.


Our universe has been expanding since it began (Credit: Chris Butler/SPL)


Our first clue to the end of the universe comes from thermodynamics, the study of heat. Thermodynamics is the wild-eyed street preacher of physics, bearing a cardboard placard with a simple warning: "THE HEAT DEATH IS COMING".

Despite the name, the heat death of the universe isn't a fiery inferno. Instead, it's the death of all differences in heat.

This may not sound scary, but the heat death is far worse than being burnt to a crisp. That's because nearly everything in everyday life requires some kind of temperature difference, either directly or indirectly.

For instance, your car runs because it's hotter inside its engine than outside. Your computer runs on electricity from the local power plant, which probably works by heating water and using that to power a turbine. And you run on food, which exists thanks to the enormous temperature difference between the Sun and the rest of the universe.


The universe will end in one of four ways (Credit: Carlos Clarivan/SPL)


However, once the universe reaches heat death, everything everywhere will be the same temperature. That means nothing interesting will ever happen again.

Every star will die, nearly all matter will decay, and eventually all that will be left is a sparse soup of particles and radiation. Even the energy of that soup will be sapped away over time by the expansion of the universe, leaving everything just a fraction of a degree above absolute zero.

In this "Big Freeze", the universe ends up uniformly cold, dead and empty.

After the development of thermodynamics in the early 1800s, heat death looked like the only possible way the universe could end. But 100 years ago, Albert Einstein's theory of general relativity suggested that the universe had a far more dramatic fate.


Galaxies like M74 are rushing away from us (Credit: Chris Butler/SPL)


General relativity says that matter and energy warp space and time. This relationship between space-time and matter-energy (stuff) — between the stage and the actors on it — extends to the entire universe. The stuff in the universe, according to Einstein, determines the ultimate fate of the universe itself.

The theory predicted that the universe as a whole must either be expanding or contracting. It could not stay the same size. Einstein realized this in 1917, and was so reluctant to believe it that he fudged his own theory.

Then in 1929, the American astronomer Edwin Hubble found hard evidence that the universe was expanding. Einstein changed his mind, calling his previous insistence on a static universe the "greatest blunder" of his career.

If the universe is expanding, it must once have been much smaller than it is now. This realization led to the Big Bang theory: the idea that the universe began as something incredibly small, and then expanded incredibly quickly. We can see the "afterglow" of the Big Bang even today, in the cosmic microwave background radiation – a constant stream of radio waves, coming from all directions in the sky.


The cosmic microwave background (Credit: ESA Planck Collaboration/SPL)


The fate of the universe, then, hinges on a very simple question: will the universe continue to expand, and how quickly?

For a universe containing normal "stuff", such as matter and light, the answer to this question depends on how much stuff there is. More stuff means more gravity, which pulls everything back together and slows the expansion.

As long as the amount of stuff doesn't go over a critical threshold, the universe will continue to expand forever, and eventually suffer heat death, freezing out.

But if there's too much stuff, the expansion of the universe will slow down and stop. Then the universe will begin to contract. A contracting universe will shrink smaller and smaller, getting hotter and denser, eventually ending in a fabulously compact inferno, a sort of reverse Big Bang known as the Big Crunch.


The universe might collapse on itself, in a "Big Crunch" (Credit: Mark Garlick/SPL)


For most of the 20th century, astrophysicists weren't sure which of these scenarios would play out. Would it be the Big Freeze or the Big Crunch? Ice or fire?

They tried to perform a cosmic census, adding up how much stuff there is in our universe. It turned out that we're strangely close to the critical threshold, leaving our fate uncertain.

That all changed at the end of the 20th century. In 1998, two competing teams of astrophysicists made an astonishing announcement: the expansion of the universe is speeding up.

Normal matter and energy can't make the universe behave this way. This was the first evidence of a fundamentally new kind of energy, dubbed "dark energy", which didn't behave like anything else in the cosmos.

Dark energy pulls the universe apart. We still don't understand what it is, but roughly 70% of the energy in the universe is dark energy, and that number is growing every day.


The Big Crunch would bring our universe to a fiery end (Credit: Mehau Kulyk/SPL)


The existence of dark energy means that the amount of stuff in the universe doesn't get to determine its ultimate fate.

Instead, dark energy controls the cosmos, accelerating the expansion of the universe for all time. This makes the Big Crunch much less likely.

But that doesn't mean that the Big Freeze is inevitable. There are other possibilities.

One of them originated, not in the study of the cosmos, but in the world of subatomic particles. This is perhaps the strangest fate for the universe. It sounds like something out of science fiction, and in a way, it is.


Water can sometimes stay liquid below its freezing point (Credit: Tomas Sobek, CC by 2.0)


In Kurt Vonnegut's classic sci-fi novel Cat's Cradle, ice-nine is a new form of water ice with a remarkable property: it freezes at 46 °C, not at 0 °C. When a crystal of ice-nine is dropped into a glass of water, all the water around it immediately patterns itself after the crystal, since it has lower energy than liquid water.

The new crystals of ice-nine do the same thing to the water around them, and in the blink of an eye, the chain reaction turns all the water in the glass — or (spoiler alert!) all of Earth's oceans — into solid ice-nine.

The same thing can happen in real life with normal ice and normal water. If you put very pure water into a very clean glass, and cool it just below 0°C, the water will become supercooled: it stays liquid below its natural freezing point. There are no impurities in the water and no rough patches on the glass, so there's nowhere for the ice to start forming. But if you drop a crystal of ice into the glass, the water will freeze rapidly, just like ice-nine.

Ice-nine and supercooled water may not seem relevant to the fate of the universe. But something similar could happen to space itself.


Empty vacuum could suddenly drop to a lower energy level (Credit: Richard Kail/SPL)


Quantum physics dictates that even in a totally empty vacuum, there is a small amount of energy. But there might also be some other kind of vacuum, which holds less energy.

If that's true, then the entire universe is like a glass of supercooled water. It will only last until a "bubble" of lower-energy vacuum shows up.

Fortunately, there are no such bubbles that we're aware of. Unfortunately, quantum physics also dictates that if a lower-energy vacuum is possible, then a bubble of that vacuum will inevitably dart into existence somewhere in the universe.

When that happens, just like ice-nine, the new vacuum will "convert" the old vacuum around it. The bubble would expand at nearly the speed of light, so we'd never see it coming.


Even completely empty space contains energy (Credit: Equinox Graphics/SPL)


Inside the bubble, things would be radically different, and not terribly hospitable.

The properties of fundamental particles like electrons and quarks could be entirely different, radically rewriting the rules of chemistry and perhaps preventing atoms from forming.

Humans, planets and even the stars themselves would be destroyed in this Big Change. In a 1980 paper, Physicists Sidney Coleman and Frank de Luccia called it "the ultimate ecological catastrophe".

Adding insult to injury, dark energy would probably behave differently after the Big Change. Rather than driving the universe to expand faster, dark energy might instead pull the universe in on itself, collapsing into a Big Crunch.


Phantom dark energy could destroy everything (Credit: Detlev van Ravenswaay/SPL)


There is a fourth possibility, and once again dark energy is at centre stage. This idea is very speculative and unlikely, but it can't yet be ruled out. Dark energy might be even more powerful than we thought, and might be enough to end the universe on its own, without any intervening Big Change, Freeze, or Crunch.

Dark energy has a peculiar property. As the universe expands, its density remains constant. That means more of it pops into existence over time, to keep pace with the increasing volume of the universe. This is unusual, but doesn't break any laws of physics.

However, it could get weirder. What if the density of dark energy increases as the universe expands? In other words, what if the amount of dark energy in the universe increases more quickly than the expansion of the universe itself?

This idea was put forward by Robert Caldwell of Dartmouth College in Hanover, New Hampshire. He calls it "phantom dark energy". It leads to a remarkably strange fate for the universe.


The Big Rip would begin by tearing galaxies apart (Credit: Detlev van Ravenswaay/SPL)


If phantom dark energy exists, then the dark side is our ultimate downfall, just like Star Wars warned us it would be.

Right now, the density of dark energy is very low, far less than the density of matter here on Earth, or even the density of the Milky Way galaxy, which is much less dense than Earth. But as time goes on, the density of phantom dark energy would build up, and tear the universe apart.

In a 2003 paper, Caldwell and his colleagues outlined a scenario they called "cosmic doomsday". Once the phantom dark energy becomes more dense than a particular object, that object gets torn to shreds.

First, phantom dark energy would pull the Milky Way apart, sending its constituent stars flying. Then the solar system would be unbound, because the pull of dark energy would be stronger than the pull of the Sun on the Earth.

Finally, in a few frantic minutes the Earth would explode. Then atoms themselves would shatter, a fraction of a second before the universe itself ripped apart. Caldwell calls this the Big Rip.


The Big Rip would literally tear planets and stars apart (Credit: Nicolle R. Fuller/SPL)


The Big Rip is, by Caldwell's own admission, "very outlandish" – and not just because it sounds like something out of an over-the-top superhero comic.

Phantom dark energy flies in the face of some fairly basic ideas about the universe, like the assumption that matter and energy can't go faster than the speed of light. There are good reasons not to believe in it.

Based on our observations of the expansion of the universe, and particle physics experiments, it seems much more likely that the ultimate fate of our universe is a Big Freeze, possibly followed by a Big Change and a final Big Crunch.

But this is a remarkably grim portrait of the future — aeons of cold emptiness, finally terminated by a vacuum decay and a final implosion into nothingness. Is there any escape? Or are we doomed to book a table at the Restaurant at the End of the Universe?


All this shall pass, but not for a very long time (Credit: Allan Morton/Dennis/Milon/SPL)


There's certainly no reason for us, individually, to worry about the end of the universe. All of these events are trillions of years into the future, with the possible exception of the Big Change, so they're not exactly an imminent problem.

Also, there's no reason to worry about humanity. If nothing else, genetic drift will have rendered our descendants unrecognizable long before then. But could intelligent feeling creatures of any kind, human or not, survive?

Physicist Freeman Dyson of the Institute for Advanced Studies in Princeton, New Jersey considered this question in a classic paper published in 1979. At the time, he concluded that life could modify itself to survive the Big Freeze, which he thought was less challenging than the inferno of the Big Crunch.

But these days, he's much less optimistic, thanks to the discovery of dark energy.

"If the universe is accelerating, that's really bad news," says Dyson. Accelerating expansion means we'll eventually lose contact with all but a handful of galaxies, dramatically limiting the amount of energy available to us. "It's a rather dismal situation in the long run."

The situation could still change. "We really don't know whether the expansion is going to continue since we don't understand why it's accelerating," says Dyson. "The optimistic view is that the acceleration will slow down as the universe gets bigger." If that happens, "the future is much more promising."

But what if the expansion doesn't slow down, or if it becomes clear that the Big Change is coming? Some physicists have proposed a solution that is solidly in mad-scientist territory. To escape the end of the universe, we should build our own universe in a laboratory, and jump in.


Just after it was born, the universe inflated rapidly (Credit: David Parker/SPL)


One physicist who has worked on this idea is Alan Guth of MIT in Cambridge, Massachusetts, who is known for his work on the very early universe.

"I can't say that the laws of physics absolutely imply that it's possible," says Guth. "If it is possible, it would require technology vastly beyond anything that we can foresee. It would require huge amounts of energy that one would need to be able to obtain and control."

The first step, according to Guth, would be creating an incredibly dense form of matter — so dense that it was on the verge of collapsing into a black hole. By doing that in the right way, and then quickly clearing the matter out of the area, you might be able to force that region of space to start expanding rapidly.

In effect, you would jump-start the creation of an entirely new universe. As the space in the region expanded, the boundary would shrink, creating a bubble of warped space where the inside was bigger than the outside.


The Big Bang: the birth of a universe (Credit: Detlev van Ravenswaay/SPL)


That may sound familiar to Doctor Who fans, and according to Guth, the TARDIS is "probably a very accurate analogy" for the kind of warping of space he's talking about.

Eventually, the outside would shrink to nothingness, and the new baby universe would pinch off from our own, spared from whatever fate our universe may meet.

It's far from certain that this scheme would actually work. "I would have to say that it's unclear," says Guth. "We don't really know if it's possible or not."

However, Guth also points out that there is another source of hope beyond the end of the universe – well, hope of a sort.


Other universe may be appearing all the time (Credit: Detlev van Ravenswaay/SPL)


Guth was the first to propose that the very early universe expanded astonishingly fast for a tiny fraction of a second, an idea known as "inflation". Many cosmologists now believe inflation is the most promising approach for explaining the early universe, and Guth's plan for creating a new universe relies on recreating this rapid expansion.

Inflation has an intriguing consequence for the ultimate fate of the universe. The theory dictates that the universe we inhabit is just one small part of a multiverse, with an eternally inflating background continually spawning "pocket universes" like our own.

"If that's the case, even if we're convinced that an individual pocket universe will ultimately die through refrigeration, the multiverse as a whole will go on living forever, with new life being created in each pocket universe as it's created," says Guth. "In this picture, the multiverse as a whole is genuinely eternal, at least eternal into the future, even as individual pocket universes live and die."

In other words, Franz Kafka may have been right on the money when he said that there is "plenty of hope, an infinite amount of hope—but not for us."

This is a bit of a bleak thought. If it upsets you, here is a picture of a cute kitten.


Cheer up, by the time it happens we'll all be long gone (Credit: Alan Huett, CC by 2.0)


http://www.bbc.com/earth/story/20150602-how-will-the-universe-end

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

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

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

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

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

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

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

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

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

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

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

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 ]

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

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

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

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

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.

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 ]