One of the unsolved mysteries of contemporary science is how highly organized structures can emerge from the random motion of particles. This applies to many situations ranging from astrophysical objects that extend over millions of light years to the birth of life on Earth.
The surprising discovery of self-organized electromagnetic fields in counter-streaming ionized gases (also known as plasmas) will give scientists a new way to explore how order emerges from chaos in the cosmos. This breakthrough finding was published online in the journal, Nature Physics on Sept. 30.
"We’ve created a model for exploring how electromagnetic fields help organize ionized gas or plasma in astrophysical settings, such as in the plasma flows that emerge from young stars," said lead author Nathan Kugland, a postdoctoral researcher in the High Energy Density Science Group at Lawrence Livermore National Laboratory (LLNL). "These fields help shape the flows, and likely play a supporting role alongside gravity in the formation of solar systems, which can eventually lead to the creation of planets like the Earth."
"This observation was completely unexpected, since the plasmas move so quickly that they should freely stream past each other," explained Hye-Sook Park, team leader and staff physicist at LLNL. Park added that "laser-driven plasma experiments can study the microphysics of plasma interaction and structure formation under controlled conditions."
Studying astrophysics with laboratory experiments can help answer questions about astrophysical objects that are far beyond the reach of direct measurements. This research is being carried out as part of a large international collaboration, Astrophysical Collisionless Shock Experiments with Lasers (ACSEL), led by LLNL, Princeton University, Osaka University and Oxford University, with many other universities participating.
This work was performed at the OMEGA EP laser by the Lawrence Livermore National Laboratory. Additional support was provided by the LDRD program and the International Collaboration for High Energy Density Science (ICHEDS), supported by the Core-to-Core Program of the Japan Society for the Promotion of Science. The research leading to these results received funding from the European Research Council under the European Community’s Seventh Framework Programme.
(via Science Daily)
The implicate order is a school of thought that proposes there are forms of consciousness and principles of matter at work in the universe that we humans do not perceive. Jung interpreted this as the basis for synchronicity. The entirety of the universe exists inside of us, though we are only a very small part of it.
The leap from our universe to another is theoretically possible, say physicists. And the technology to test the idea is available today
The idea that our universe is embedded in a broader multidimensional space has captured the imagination of scientists and the general population alike.
This notion is not entirely science fiction. According to some theories, our cosmos may exist in parallel with other universes in other sets of dimensions. Cosmologists call these universes braneworlds. And among that many prospects that this raises is the idea that things from our Universe might somehow end up in another.
A couple of years ago, Michael Sarrazin at the University of Namur in Belgium and a few others showed how matter might make the leap in the presence of large magnetic potentials. That provided a theoretical basis for real matter swapping.
Today, Sarrazin and a few pals say that our galaxy might produce a magnetic potential large enough to make this happen for real. If so, we ought to be able to observe matter leaping back and forth between universes in the lab. In fact, such observations might already have been made in certain experiments.
The experiments in question involve trapping ultracold neutrons in bottles at places like the Institut Laue Langevin in Grenoble, France, and the Saint Petersburg Institute of Nuclear Physics. Ultracold neutrons move so slowly that it is possible to trap them using ‘bottles’ made of magnetic fields, ordinary matter and even gravity.
One reason to do this is to measure how quickly the neutrons decay by beta emission. So physicists measure the rate at which the neutrons hit the bottle walls and how quickly this drops.
There are two processes at work here: the rate of neutron decay and the rate at which neutrons escape from the bottle. So in the case of an ideal bottle, the rate of decay should be equal to the beta decay rate. But the bottles are not ideal so the rate of decay is always faster.
That leaves open the possibility that there might be a third process at work: that some of the extra decay might be the result of neutrons jumping from our universe to another.
So Sarrazin and co have used the measured decay rates to place an upper limit on how often this can happen.
Their conclusion is that the probability of a neutron jumping ship is smaller than about one in a million.
That doesn’t really say anything about whether matter swapping actually takes place. Only that if it does, it doesn’t happen very often.
However, Sarrazzin and co also say it should be straightforward to take better data that places stricter limits.
According to their theoretical work, a change in the gravitational potential should also influence the rate of matter swapping. So one idea is to carry out a neutron trapping experiment that lasts for a year or more, allowing the Earth to complete at least one orbit of the Sun.
In that time, the gravitational potential changes in a way that should influence the rate of matter swapping. Indeed, there ought to be an annual cycle. “If one can detect such a modulation it would be a strong indication that matter swapping really occurs,” they say.
That would be one of the biggest and most controversial discoveries in modern physics and one that is possible with technologies available today.
Anyone got an old neutron bottle lying around and a bit of spare time on their hands?
Ref: arxiv.org/abs/1201.3949: Experimental Limits On Neutron Disappearance Into Another Braneworld
(via Technology Review)
A laser powerful enough to tear apart the fabric of space could be built in Britain as part major new scientific project that aims to answer some of the most fundamental questions about our universe.
Due to follow in the footsteps of the Large Hadron Collider, the latest “big science” experiment being proposed by physicists will see the world’s most powerful laser being constructed.
Capable of producing a beam of light so intense that it would be equivalent to the power received by the Earth from the sun focused onto a speck smaller than a tip of a pin, scientists claim it could allow them boil the very fabric of space – the vacuum.
Contrary to popular belief, a vacuum is not devoid of material but in fact fizzles with tiny mysterious particles that pop in and out of existence, but at speeds so fast that no one has been able to prove they exist.
The Extreme Light Infrastructure Ultra-High Field Facility would produce a laser so intense that scientists say it would allow them to reveal these particles for the first time by pulling this vacuum “fabric” apart.
They also believe it could even allow them to prove whether extra-dimensions exist.
[This New Scientist article is only available to subscribers so it has been presented here in its entirety.]
SUBATOMIC particles have broken the universe’s fundamental speed limit, or so it was reported last week. The speed of light is the ultimate limit on travel in the universe, and the basis for Einstein’s special theory of relativity, so if the finding stands up to scrutiny, does it spell the end for physics as we know it? The reality is less simplistic and far more interesting.
"People were saying this means Einstein is wrong," says physicist Heinrich Päs of the Technical University of Dortmund in Germany. "But that’s not really correct."
Instead, the result could be the first evidence for a reality built out of extra dimensions. Future historians of science may regard it not as the moment we abandoned Einstein and broke physics, but rather as the point at which our view of space vastly expanded, from three dimensions to four, or more.
"This may be a physics revolution," says Thomas Weiler at Vanderbilt University in Nashville, Tennessee, who has devised theories built on extra dimensions. "The famous words ‘paradigm shift’ are used too often and tritely, but they might be relevant."
The subatomic particles - neutrinos - seem to have zipped faster than light from CERN, near Geneva, Switzerland, to the OPERA detector at the Gran Sasso lab near L’Aquila, Italy. It’s a conceptually simple result: neutrinos making the 730-kilometre journey arrived 60 nanoseconds earlier than they would have if they were travelling at light speed. And it relies on three seemingly simple measurements, says Dario Autiero of the Institute of Nuclear Physics in Lyon, France, a member of the OPERA collaboration: the distance between the labs, the time the neutrinos left CERN, and the time they arrived at Gran Sasso.
But actually measuring those times and distances to the accuracy needed to detect nanosecond differences is no easy task. The OPERA collaboration spent three years chasing down every source of error they could imagine (see illustration) before Autiero made the result public in a seminar at CERN on 23 September.
Physicists grilled Autiero for an hour after his talk to ensure the team had considered details like the curvature of the Earth, the tidal effects of the moon and the general relativistic effects of having two clocks at different heights (gravity slows time so a clock closer to Earth’s surface runs a tiny bit slower).
They were impressed. “I want to congratulate you on this extremely beautiful experiment,” said Nobel laureate Samuel Ting of the Massachusetts Institute of Technology after Autiero’s talk. “The experiment is very carefully done, and the systematic error carefully checked.”
Most physicists still expect some sort of experimental error to crop up and explain the anomaly, mainly because it contravenes the incredibly successful law of special relativity which holds that the speed of light is a constant that no object can exceed. The theory also leads to the famous equation E = mc2.
Hotly anticipated are results from other neutrino detectors, including T2K in Japan and MINOS at Fermilab in Illinois, which will run similar experiments and confirm the results or rule them out (see “Fermilab stops hunting Higgs, starts neutrino quest”).
In 2007, the MINOS experiment searched for faster-than-light neutrinos but didn’t see anything statistically significant. The team plans to reanalyse its data and upgrade the detector’s stopwatch. “These are the kind of things that we have to follow through, and make sure that our prejudices don’t get in the way of discovering something truly fantastic,” says Stephen Parke of Fermilab.
In the meantime, suggests Sandip Pakvasa of the University of Hawaii, let’s suppose the OPERA result is real. If the experiment is tested and replicated and the only explanation is faster-than-light neutrinos, is E = mc2 done for?
Not necessarily. In 2006, Pakvasa, Päs and Weiler came up with a model that allows certain particles to break the cosmic speed limit while leaving special relativity intact. “One can, if not rescue Einstein, at least leave him valid,” Weiler says.
The trick is to send neutrinos on a shortcut through a fourth, thus-far-unobserved dimension of space, reducing the distance they have to travel. Then the neutrinos wouldn’t have to outstrip light to reach their destination in the observed time.
In such a universe, the particles and forces we are familiar with are anchored to a four-dimensional membrane, or “brane”, with three dimensions of space and one of time. Crucially, the brane floats in a higher dimensional space-time called the bulk, which we are normally completely oblivious to.
The fantastic success of special relativity up to now, plus other cosmological observations, have led physicists to think that the brane might be flat, like a sheet of paper. Quantum fluctuations could make it ripple and roll like the surface of the ocean, Weiler says. Then, if neutrinos can break free of the brane, they might get from one point on it to another by dashing through the bulk, like a flying fish taking a shortcut between the waves (see illustration).
This model is attractive because it offers a way out of one of the biggest theoretical problems posed by the OPERA result: busting the apparent speed limit set by neutrinos detected pouring from a supernova in 1987.
As stars explode in a supernova, most of their energy streams out as neutrinos. These particles hardly ever interact with matter. That means they should escape the star almost immediately, while photons of light will take about 3 hours. In 1987, trillions of neutrinos arrived at Earth 3 hours before the dying star’s light caught up. If the neutrinos were travelling as fast as those going from CERN to OPERA, they should have arrived in 1982.
OPERA’s neutrinos were about 1000 times as energetic as the supernova’s neutrinos, though. And Pakvasa and colleagues’ model calls for neutrinos with a specific energy that makes them prefer tunnelling through the bulk to travelling along the brane. If that energy is around 20 gigaelectronvolts - and the team don’t yet know that it is - “then you expect large effects in the OPERA region, and small effects at the supernova energies,” Pakvasa says. He and Päs are meeting next week to work out the details.
The flying fish shortcut isn’t available to all particles. In the language of string theory, a mathematical model some physicists hope will lead to a comprehensive “theory of everything”, most particles are represented by tiny vibrating strings whose ends are permanently stuck to the brane. One of the only exceptions is the theoretical "sterile neutrino", represented by a closed loop of string. These are also the only type of neutrino thought capable of escaping the brane.
Neutrinos are known to switch back and forth between their three observed types (electron, muon and tau neutrinos), and OPERA was originally designed to detect these shifts. In Pakvasa’s model, the muon neutrinos produced at CERN could have transformed to sterile neutrinos mid-flight, made a short hop through the bulk, and then switched back to muon before reappearing on the brane.
So if OPERA’s results hold up, they could provide support for the existence of sterile neutrinos, extra dimensions and perhaps string theory. Such theories could also explain why gravity is so weak compared with the other fundamental forces. The theoretical particles that mediate gravity, known as gravitons, may also be closed loops of string that leak off into the bulk. “If, in the end, nobody sees anything wrong and other people reproduce OPERA’s results, then I think it’s evidence for string theory, in that string theory is what makes extra dimensions credible in the first place,” Weiler says.
Meanwhile, alternative theories are likely to abound. Weiler expects papers to appear in a matter of days or weeks.
Even if relativity is pushed aside, Einstein has worked so well for so long that he will never really go away. At worst, relativity will turn out to work for most of the universe but not all, just as Newton’s mechanics work until things get extremely large or small. “The fact that Einstein has worked for 106 years means he’ll always be there, either as the right answer or a low-energy effective theory,” Weiler says.
(via New Scientist)
Related reading » Neutrinos: Everything you need to know
"…We don’t allow faster-than-light neutrinos in here," says the barman. A neutrino walks into a bar…" As reports spread of subatomic particles moving faster than light and potentially travelling through time, such gags were born. But apparently super-hasty motion is not the only strange thing about neutrinos.
What exactly are they?
With a neutral charge and nearly zero mass, neutrinos are the shadiest of particles, rarely interacting with ordinary matter and slipping through our bodies, buildings and the Earth at a rate of trillions per second.
First predicted in 1930 by Wolfgang Pauli, who won a Nobel prize for this work in 1945, they are produced in various nuclear reactions: fusion, which powers the sun; fission, harnessed by humans to make weapons and energy; and during natural radioactive decay inside the Earth.
If they are so stealthy, how do we know they are there at all?
Wily neutrinos usually avoid contact with matter, but every so often, they crash into an atom to produce a signal that allows us to observe them. Fredrick Reines first detected them in 1956, garnering himself a Nobel prize in 1995.
Most commonly, experiments use large pools of water or oil. When neutrinos interact with electrons or nuclei of those water or oil molecules, they give off a flash of light that sensors can detect.
Where are these experiments found?
These days, a lot of expense and extreme engineering go into detectors that are sunk into the ground to shield them from extraneous particles that might interfere with them. For instance, OPERA, which detected the apparently faster-than-light neutrinos beamed from CERN, lies inside the Gran Sasso mountain in Italy. This works because neutrinos shoot straight through such shields.
What’s cool about neutrinos?
Their stealth belies their potential importance. Take extra dimensions. Most particles come in two varieties: ones that spin clockwise and ones that spin anticlockwise. Neutrinos are the only particles that seem to just spin anticlockwise. Some theorists say this is evidence for extra dimensions, which could host the “missing”, right-handed neutrinos.
Unseen right-handed neutrinos may also account for mysterious dark matter. This is thought to make up 80 per cent of all matter in the universe and to stop galaxies from flying apart. The idea is that right-handed neutrinos might be much heavier than left-handed ones and so could provide the requisite gravity.
And what’s this about them coming in “flavours”?
Another strange thing about neutrinos is that they come in at least three types or “flavours” – tau, electron and muon – and can morph from one flavour to another. Recent experiments suggest there may be differences in the ways that antineutrinos and neutrinos morph, which might in turn explain how an imbalance of matter and antimatter arose in the early universe.
Do they have any practical applications?
Sort of – and more are in the works. Some physicists hope to detect neutrinos given off by secret nuclear reactors. Others dream of using them as the basis of a novel communication system that would allow messages to be transmitted to the other side of the world without wires, cables or satellites. Meanwhile the underwater ANTARES detector is doubling up as a telescope for marine life. That’s because, as well as neutrinos, it can detect the light given off by luminous organisms and bacteria.
(via New Scientist)
At the heart of the experiment is one of the weirdest, and most important, tenets of quantum mechanics: the principle that empty space is anything but. Quantum theory predicts that a vacuum is actually a writhing foam of particles flitting in and out of existence.
This is the kind of news I love waking up to.
Recent discoveries require us to rethink our understanding of history. “The histories of the universe,” said renowned physicist Stephen Hawking “depend on what is being measured, contrary to the usual idea that the universe has an objective observer-independent history.”
Is it possible we live and die in a world of illusions? Physics tells us that objects exist in a suspended state until observed, when they collapse in to just one outcome. Paradoxically, whether events happened in the past may not be determined until sometime in your future — and may even depend on actions that you haven’t taken yet.
In 2002, scientists carried out an amazing experiment, which showed that particles of light “photons” knew — in advance −- what their distant twins would do in the future. They tested the communication between pairs of photons — whether to be either a wave or a particle. Researchers stretched the distance one of the photons had to take to reach its detector, so that the other photon would hit its own detector first. The photons taking this path already finished their journeys -− they either collapse into a particle or don’t before their twin encounters a scrambling device. Somehow, the particles acted on this information before it happened, and across distances instantaneously as if there was no space or time between them. They decided not to become particles before their twin ever encountered the scrambler. It doesn’t matter how we set up the experiment. Our mind and its knowledge is the only thing that determines how they behave. Experiments consistently confirm these observer-dependent effects.
More recently (Science 315, 966, 2007), scientists in France shot photons into an apparatus, and showed that what they did could retroactively change something that had already happened. As the photons passed a fork in the apparatus, they had to decide whether to behave like particles or waves when they hit a beam splitter. Later on - well after the photons passed the fork - the experimenter could randomly switch a second beam splitter on and off. It turns out that what the observer decided at that point, determined what the particle actually did at the fork in the past. At that moment, the experimenter chose his history.
Of course, we live in the same world. Particles have a range of possible states, and it’s not until observed that they take on properties. So until the present is determined, how can there be a past? According to visionary physicist John Wheeler (who coined the word “black hole”), “The quantum principle shows that there is a sense in which what an observer will do in the future defines what happens in the past.” Part of the past is locked in when you observe things and the “probability waves collapse.” But there’s still uncertainty, for instance, as to what’s underneath your feet. If you dig a hole, there’s a probability you’ll find a boulder. Say you hit a boulder, the glacial movements of the past that account for the rock being in exactly that spot will change as described in the Science experiment.
But what about dinosaur fossils? Fossils are really no different than anything else in nature. For instance, the carbon atoms in your body are “fossils” created in the heart of exploding supernova stars. Bottom line: reality begins and ends with the observer. “We are participators,” Wheeler said “in bringing about something of the universe in the distant past.” Before his death, he stated that when observing light from a quasar, we set up a quantum observation on an enormously large scale. It means, he said, the measurements made on the light now, determines the path it took billions of years ago.
Like the light from Wheeler’s quasar, historical events such as who killed JFK, might also depend on events that haven’t occurred yet. There’s enough uncertainty that it could be one person in one set of circumstances, or another person in another. Although JFK was assassinated, you only possess fragments of information about the event. But as you investigate, you collapse more and more reality. According to biocentrism, space and time are relative to the individual observer - we each carry them around like turtles with shells.
History is a biological phenomenon − it’s the logic of what you, the animal observer experiences. You have multiple possible futures, each with a different history like in the Science experiment. Consider the JFK example: say two gunmen shot at JFK, and there was an equal chance one or the other killed him. This would be a situation much like the famous Schrödinger’s cat experiment, in which the cat is both alive and dead − both possibilities exist until you open the box and investigate.
"We must re-think all that we have ever learned about the past, human evolution and the nature of reality, if we are ever to find our true place in the cosmos," says Constance Hilliard, a historian of science at UNT. Choices you haven’t made yet might determine which of your childhood friends are still alive, or whether your dog got hit by a car yesterday. In fact, you might even collapse realities that determine whether Noah’s Ark sank. "The universe," said John Haldane, "is not only queerer than we suppose, but queerer than we can suppose.”
— Robert Lanza
One of the central planks of quantum mechanics was called into question in a new take on the classic two-slit experiment.
One of the central notions in quantum mechanics is that light and matter can behave as both particle and wave. The principle of “complementarity” has always been understood to prevent the observation of both behaviours simultaneously. However, new research published in Science on 2 June, suggests that physicists at the University of Toronto and Griffith University in Brisbane have for the first time observed both behaviours at the same time.
In Thomas Young’s 19th century “two-slit experiment”, light is passed through two tiny holes and is then viewed on a screen. The two beams interfere with each other, forming a diffraction pattern, as if the light were made of waves. If one of the slits is blocked, the light can be seen as a single beam on the screen, as if light were made of particles. The two-slit experiment shows that, depending on how it’s measured, a photon will act like either a particle or a wave, but never both.
Aephraim Steinberg of the University of Toronto and Sacha Kocsis of Griffith recreated this experiment, easily observing the interference pattern indicative of the wave nature of light. But significantly, they were also able measure the path of the particles of light.
Science reporter, Adrian Cho elaborates on the importance of their new research:
"For decades, [the] experiment has served as physicists’ canonical example of the uncertainty principle: the law of nature that says you can’t know both where a subatomic particle is and how fast it is moving, and thus can’t trace its trajectory. But now physicists have tweaked that classic experiment to show that they can follow the average path taken by many particles."
Steinberg and his team allowed photons to pass through a calcite crystal which gave each photon a small deviation in its path. By measuring the light patterns on a camera, the team was able to deduce what paths the photons had taken. They clearly saw the interference pattern which infers the wave nature of light, but surprisingly they also could see from which slits the photons had come from, a telltale sign of the particle nature of light.
Marlan Scully, a quantum physicist at Texas University, commented:
"It’s a beautiful series of measurements by an excellent group, the likes of which I’ve not seen before.",
"This paper is probably the first that has really put this weak measurement idea into a real experimental realisation." He said that the work would - inevitably - raise philosophical issues as well. "The exact way to think about what they’re doing will be researched for some time, and the weak measurement concept itself will be a matter of controversy"
Professor Steinberg commented, “I feel like we’re starting to pull back a veil on what nature really is”.
(via Particle Decelerator)
A world-class team of physicists studying the cosmic microwave background (CMB), light emitted when the Universe was just 400,000 years old have claimed that our view of the early Universe may contain the signature of a time before the Big Bang. Their discovery may help explain why we experience time moving in a straight line from yesterday into tomorrow.
The CMB is relic radiation that fills the entire Universe and is regarded as the most conclusive evidence for the Big Bang. Although this microwave background is mostly smooth, the Cobe satellite in 1992 discovered small fluctuations that were believed to be the seeds from which the galaxy clusters we see in today’s Universe grew.
Dr Adrienne Erickcek, from the California Institute of Technology (Caltech), and colleagues believe these fluctuations contain hints that our Universe “bubbled off” from a previous one. Their data came from Nasa’s Wilkinson Microwave Anisotropy Probe (WMAP), which has been studying the CMB since its launch in 2001.
Their model suggests that new universes could be created spontaneously from apparently empty space. From inside the parent universe, the event would be surprisingly unspectacular.
Describing the team’s work, California Institute of Technology professor Sean Carroll explained that “a universe could form inside this room and we’d never know”.
The inspiration for their theory isn’t just an explanation for the Big Bang our Universe experienced 13.7 billion years ago, but lies in an attempt to explain one of the largest mysteries in physics - why time seems to move in one direction. The laws that govern physics on a microscopic scale are completely reversible, and yet, as Professor Carroll commented, “no one gets confused about which is yesterday and which is tomorrow.” Carroll added: “Every time you break an egg or spill a glass of water you’re learning about the Big Bang.”
Physicists have long blamed this one-way movement, known as the “arrow of time”, on a physical rule known as the second law of thermodynamics, which insists that systems move over time from order to disorder.
This rule is so fundamental to physics that pioneering astronomer Arthur Eddington insisted that “if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation”.
The second law cannot be escaped, but Carroll pointed out that it depends on a major assumption - that the Universe began its life in an ordered state.
In his presentation, the Caltech astronomer explained that by creating a Big Bang from the cold space of a previous universe, the new universe begins its life in just such an ordered state. The apparent direction of time - and the fact that it’s hard to put a broken egg back together - is the consequence.
Much work remains to be done on the theory: the researchers’ first priority will be to calculate the odds of a new universe appearing from a previous one. In the meantime, the team has turned to the results from WMAP. Detailed measurements made by the satellite have shown that the fluctuations in the microwave background are about 10% stronger on one side of the sky than those on the other.
Carroll conceded that this might just be a coincidence, but pointed out that a natural explanation for this discrepancy would be if it represented a structure inherited from our universe’s parent.
Meanwhile, Professor Carroll urged cosmologists to broaden their horizons: “We’re trained to say there was no time before the Big Bang, when we should say that we don’t know whether there was anything - or if there was, what it was.”
If the Caltech team’s work is correct, we may already have the first information about what came before our own Universe.
A theory of reality beyond Einstein’s universe is taking shape – and a mysterious cosmic signal could soon fill in the blanks It wasn’t so long ago we thought space and time were the absolute and unchanging scaffolding of the universe. Then along came Albert Einstein, who showed that different observers can disagree about the length of objects and the timing of events. His theory of relativity unified space and time into a single entity - space-time. It meant the way we thought about the fabric of reality would never be the same again. “Henceforth space by itself, and time by itself, are doomed to fade into mere shadows,” declared mathematician Hermann Minkowski. “Only a kind of union of the two will preserve an independent reality.” But did Einstein’s revolution go far enough? Physicist Lee Smolin at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, doesn’t think so. He and a trio of colleagues are aiming to take relativity to a whole new level, and they have space-time in their sights. They say we need to forget about the home Einstein invented for us: we live instead in a place called phase space. If this radical claim is true, it could solve a troubling paradox about black holes that has stumped physicists for decades. What’s more, it could set them on the path towards their heart’s desire: a “theory of everything” that will finally unite general relativity and quantum mechanics. Continue reading…
A theory of reality beyond Einstein’s universe is taking shape – and a mysterious cosmic signal could soon fill in the blanks
It wasn’t so long ago we thought space and time were the absolute and unchanging scaffolding of the universe. Then along came Albert Einstein, who showed that different observers can disagree about the length of objects and the timing of events. His theory of relativity unified space and time into a single entity - space-time. It meant the way we thought about the fabric of reality would never be the same again. “Henceforth space by itself, and time by itself, are doomed to fade into mere shadows,” declared mathematician Hermann Minkowski. “Only a kind of union of the two will preserve an independent reality.”
But did Einstein’s revolution go far enough? Physicist Lee Smolin at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, doesn’t think so. He and a trio of colleagues are aiming to take relativity to a whole new level, and they have space-time in their sights. They say we need to forget about the home Einstein invented for us: we live instead in a place called phase space.
If this radical claim is true, it could solve a troubling paradox about black holes that has stumped physicists for decades. What’s more, it could set them on the path towards their heart’s desire: a “theory of everything” that will finally unite general relativity and quantum mechanics.
The theory that our universe is contained inside a bubble, and that multiple alternative universes exist inside their own bubbles — making up the ‘multiverse’ — is, for the first time, being tested by physicists.
Two research papers published in Physical Review Letters and Physical Review D are the first to detail how to search for signatures of other universes. Physicists are now searching for disk-like patterns in the cosmic microwave background (CMB) radiation — relic heat radiation left over from the Big Bang — which could provide tell-tale evidence of collisions between other universes and our own.
Many modern theories of fundamental physics predict that our universe is contained inside a bubble. In addition to our bubble, this `multiverse’ will contain others, each of which can be thought of as containing a universe. In the other ‘pocket universes’ the fundamental constants, and even the basic laws of nature, might be different.
Until now, nobody had been able to find a way to efficiently search for signs of bubble universe collisions — and therefore proof of the multiverse — in the CMB radiation, as the disc-like patterns in the radiation could be located anywhere in the sky. Additionally, physicists needed to be able to test whether any patterns they detected were the result of collisions or just random patterns in the noisy data.
A team of cosmologists based at University College London (UCL), Imperial College London and the Perimeter Institute for Theoretical Physics has now tackled this problem.
"It’s a very hard statistical and computational problem to search for all possible radii of the collision imprints at any possible place in the sky," says Dr Hiranya Peiris, co-author of the research from the UCL Department of Physics and Astronomy. "But that’s what pricked my curiosity."
The team ran simulations of what the sky would look like with and without cosmic collisions and developed a ground-breaking algorithm to determine which fit better with the wealth of CMB data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP). They put the first observational upper limit on how many bubble collision signatures there could be in the CMB sky.
Stephen Feeney, a PhD student at UCL who created the powerful computer algorithm to search for the tell-tale signatures of collisions between “bubble universes,” and co-author of the research papers, said: “The work represents an opportunity to test a theory that is truly mind-blowing: that we exist within a vast multiverse, where other universes are constantly popping into existence.”
One of many dilemmas facing physicists is that humans are very good at cherry-picking patterns in the data that may just be coincidence. However, the team’s algorithm is much harder to fool, imposing very strict rules on whether the data fits a pattern or whether the pattern is down to chance.
Dr Daniel Mortlock, a co-author from the Department of Physics at Imperial College London, said: “It’s all too easy to over-interpret interesting patterns in random data (like the ‘face on Mars’ that, when viewed more closely, turned out to just a normal mountain), so we took great care to assess how likely it was that the possible bubble collision signatures we found could have arisen by chance.”
The authors stress that these first results are not conclusive enough either to rule out the multiverse or to definitively detect the imprint of a bubble collision. However, WMAP is not the last word: new data currently coming in from the European Space Agency’s Planck satellite should help solve the puzzle.
(via Science Daily)
An ambitious experiment to make a glass sphere exist in two places at once could provide the most sensitive test of quantum theory yet. The experiment will place a sphere containing millions of atoms – making it larger than many viruses – into a superposition of states in different places, say researchers in Europe.
Physicists have questioned whether large objects can follow quantum laws ever since Erwin Schrödinger’s thought-experiment suggested a cat could exist in a superposition of being both alive and dead.
The idea is to zap a glass sphere 40 nanometres in diameter with a laser while it is inside a small cavity. This should force the sphere to bounce from one side of the cavity to the other. But since the light is quantum in nature, so too will be the position of the sphere. This forces it into a quantum superposition.
The experiment will have to be carried out in high vacuum and at extremely low temperatures so that the sphere is not disturbed by thermal noise or air molecules, says lead author Oriol Romero-Isart from the Max Planck Institute of Quantum Optics in Garching, Germany.
Last year Aaron O’Connell and colleagues at the University of California, Santa Barbara, demonstrated that it should be possible to create superpositions in a 60-micrometre-long metal strip. However, the physical separation associated with the two different states of the strip was only 1 femtometre, about the width of the nucleus of an atom.
The new experiment, in contrast, would put the glass sphere in two entirely distinct places at once, with no overlap. “In our proposal the centre of mass is put into a superposition of spatial locations separated by a distance larger than the size of the object,” Romero-Isart says.
Atom interferometer experiments have previously achieved good separation, putting fullerene and other molecules containing up to a few hundred atoms into distinct superposition states, but the new scheme will do this with truly macroscopic objects.
This will be particularly valuable in providing tests for quantum mechanics, the researchers say. Observing the behaviour of such very large objects obeying quantum laws offers our best hope of finding ways in which quantum theory breaks down.
The Romero-Isart experiment would take us “substantially beyond the current state of the art”, says Anthony Leggett of the University of Illinois at Urbana-Champaign. “Neither the fullerene experiments nor that of O’Connell and his team are able to test well-developed competitors to quantum mechanics.”
Journal reference: Physical Review Letters, DOI: 10.1103/PhysRevLett.107.020405
Fiber optic cables (pictured) could help prove the theories behind the new “space time” cloak concept.
Material would adjust speed of light to hide actions, physicists say.
It’s no illusion: Science has found a way to make not just objects but entire events disappear.
According to new research by British physicists, it’s theoretically possible to create a material that can hide an entire bank heist from human eyes and surveillance cameras.
"The concepts are basically quite simple," said Paul Kinsler, a physicist at Imperial College London, who created the idea with colleagues Martin McCall and Alberto Favaro.
Unlike invisibility cloaks—some of which have been made to work at very small scales—the event cloak would do more than bend light around an object.
Instead this cloak would use special materials filled with metallic arrays designed to adjust the speed of light passing through.
In theory, the cloak would slow down light coming into the robbery scene while the safecracker is at work. When the robbery is complete, the process would be reversed, with the slowed light now racing to catch back up.
If the “before” and “after” visions are seamlessly stitched together, there should be no visible trace that anything untoward has happened. One second there’s a closed safe, and the next second the safe has been emptied.