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by seemslikeadream » Thu Oct 16, 2014 7:14 pm
DrEvil » Thu Oct 16, 2014 3:54 pm wrote:^^ Love the idea behind this, but am I the only one who thinks the design of the player is stupid?
Can't imagine walking around with that thing in my pocket.
by DrEvil » Thu Oct 16, 2014 8:54 pm
by Pele'sDaughter » Fri Oct 17, 2014 7:30 pm
by DrEvil » Sat Oct 18, 2014 3:13 pm
Quantum Entanglement Links 2 Diamonds
Usually a finicky phenomenon limited to tiny, ultracold objects, entanglement has now been achieved for macroscopic diamonds at room temperature
Diamonds have long been available in pairs—say, mounted in a nice set of earrings. But physicists have now taken that pairing to a new level, linking two diamonds on the quantum level.
A group of researchers report in the December 2 issue of Science that they managed to entangle the quantum states of two diamonds separated by 15 centimeters. Quantum entanglement is a phenomenon by which two or more objects share an unseen link bridging the space between them—a hypothetical pair of entangled dice, for instance, would always land on matching numbers, even if they were rolled in different places simultaneously.
But that link is fragile, and it can be disrupted by any number of outside influences. For that reason entanglement experiments on physical systems usually take place in highly controlled laboratory setups—entangling, say, a pair of isolated atoms cooled to nearly absolute zero.
In the new study, researchers from the University of Oxford, the National Research Council of Canada and the National University of Singapore (NUS) showed that entanglement can also be achieved in macroscopic objects at room temperature. "What we have done is demonstrate that it's possible with more standard, everyday objects—if diamond can be considered an everyday object," says study co-author Ian Walmsley, an experimental physicist at Oxford. "It's possible to put them into these quantum states that you often associate with these engineered objects, if you like—these closely managed objects."
To entangle relatively large objects, Walmsley and his colleagues harnessed a collective property of diamonds: the vibrational state of their crystal lattices. By targeting a diamond with an optical pulse, the researchers can induce a vibration in the diamond, creating an excitation called a phonon—a quantum of vibrational energy. Researchers can tell when a diamond contains a phonon by checking the light of the pulse as it exits. Because the pulse has deposited a tiny bit of its energy in the crystal, one of the outbound photons is of lower energy, and hence longer wavelength, than the photons of the incoming pulse.
Walmsley and his colleagues set up an experiment that would attempt to entangle two different diamonds using phonons. They used two squares of synthetically produced diamond, each three millimeters across. A laser pulse, bisected by a beam splitter, passes through the diamonds; any photons that scatter off of the diamond to generate a phonon are funneled into a photon detector. One such photon reaching the detector signals the presence of a phonon in the diamonds.
But because of the experimental design, there is no way of knowing which diamond is vibrating. "We know that somewhere in that apparatus, there is one phonon," Walmsley says. "But we cannot tell, even in principle, whether that came from the left-hand diamond or the right-hand diamond." In quantum-mechanical terms, in fact, the phonon is not confined to either diamond. Instead the two diamonds enter an entangled state in which they share one phonon between them.
To verify the presence of entanglement, the researchers carried out a test to check that the diamonds were not acting independently. In the absence of entanglement, after all, half the laser pulses could set the left-hand diamond vibrating and the other half could act on the right-hand diamond, with no quantum correlation between the two objects. If that were the case, then the phonon would be fully confined to one diamond.
If, on the other hand, the phonon were indeed shared by the two entangled diamonds, then any detectable effect of the phonon could bear the imprint of both objects. So the researchers fired a second optical pulse into the diamonds, with the intent of de-exciting the vibration and producing a signal photon that indicates that the phonon has been removed from the system. The phonon's vibrational energy gives the optical pulse a boost, producing a photon with higher energy, or shorter wavelength, than the incoming photons and eliminating the phonon in the process.
Once again, there is no way of knowing which diamond produced the photon, because the paths leading from each diamond to the detectors are merged, so there is no way of knowing where the phonon was. But the researchers found that each of the photon paths leading from the diamonds to the detectors had an interfering effect on the other—adjusting how the two paths were joined affected the photon counts in the detectors. In essence, a single photon reaching the detectors carried information about both paths. So it cannot be said to have traveled down one path from one diamond: the photon, as with the vibrational phonon that produced it, came from both diamonds.
After running the experiment over and over again to gather statistically significant results, the researchers concluded with confidence that entanglement had indeed been achieved. "We can't be 100 percent certain that they're entangled, but our statistical analysis shows that we're 98 percent confident in that, and we think that's a pretty good outcome," Walmsley says.
The catch to using phonons for macroscopic entanglement is that they do not last long—only seven picoseconds, or seven trillionths of a second, in diamond. So the experimenters had to rely on extremely fast optical pulses to carry out their experiment, creating entangled states with phonons and then damping the phonons with the second pulse to test that entanglement just 0.35 picoseconds later.
Because of this brevity, such entanglement schemes may not take over for more established techniques using photons or single atoms, but Walmsley hopes that researchers will consider the possibilities of using fairly ordinary, room-temperature materials in quantum technologies. "I think it gives a new scenario and a new instantiation of something that helps point in that direction," he says.
Indeed, the new study is just the latest to show how quantum mechanics applies in real-world, macroscopic systems. Oxford and NUS physicist Vlatko Vedral, who was not involved in the new research, says it "beautifully illustrates" the point of Austrian physicist Erwin Schrödinger's famous thought experiment in which a hypothetical cat is simultaneously alive and dead. "It can't be that entanglement exists at the micro level (say of photons) but not at the macro level (say of diamonds)," because those worlds interact, Vedral wrote in an email. "Schrödinger used atoms instead of photons and cats instead of diamonds, but the point is the same."
Creation of entanglement simultaneously gives rise to a wormhole
A diagram of a wormhole, a hypothetical "shortcut" through the universe, where its two ends are each in separate points in spacetime. Credit: Wikipedia
Quantum entanglement is one of the more bizarre theories to come out of the study of quantum mechanics—so strange, in fact, that Albert Einstein famously referred to it as "spooky action at a distance."
Essentially, entanglement involves two particles, each occupying multiple states at once—a condition referred to as superposition. For example, both particles may simultaneously spin clockwise and counterclockwise. But neither has a definite state until one is measured, causing the other particle to instantly assume a corresponding state. The resulting correlations between the particles are preserved, even if they reside on opposite ends of the universe.
But what enables particles to communicate instantaneously—and seemingly faster than the speed of light—over such vast distances? Earlier this year, physicists proposed an answer in the form of "wormholes," or gravitational tunnels. The group showed that by creating two entangled black holes, then pulling them apart, they formed a wormhole—essentially a "shortcut" through the universe—connecting the distant black holes.
Now an MIT physicist has found that, looked at through the lens of string theory, the creation of two entangled quarks—the building blocks of matter—simultaneously gives rise to a wormhole connecting the pair.
The theoretical results bolster the relatively new and exciting idea that the laws of gravity holding together the universe may not be fundamental, but arise from something else: quantum entanglement.
Julian Sonner, a senior postdoc in MIT's Laboratory for Nuclear Science and Center for Theoretical Physics, has published his results in the journal Physical Review Letters, where it appears together with a related paper by Kristan Jensen of the University of Victoria and Andreas Karch of the University of Washington.
The tangled web that is gravity
Ever since quantum mechanics was first proposed more than a century ago, the main challenge for physicists in the field has been to explain gravity in quantum-mechanical terms. While quantum mechanics works extremely well in describing interactions at a microscopic level, it fails to explain gravity—a fundamental concept of relativity, a theory proposed by Einstein to describe the macroscopic world. Thus, there appears to be a major barrier to reconciling quantum mechanics and general relativity; for years, physicists have tried to come up with a theory of quantum gravity to marry the two fields.
"There are some hard questions of quantum gravity we still don't understand, and we've been banging our heads against these problems for a long time," Sonner says. "We need to find the right inroads to understanding these questions."
A theory of quantum gravity would suggest that classical gravity is not a fundamental concept, as Einstein first proposed, but rather emerges from a more basic, quantum-based phenomenon. In a macroscopic context, this would mean that the universe is shaped by something more fundamental than the forces of gravity.
This is where quantum entanglement could play a role. It might appear that the concept of entanglement—one of the most fundamental in quantum mechanics—is in direct conflict with general relativity: Two entangled particles, "communicating" across vast distances, would have to do so at speeds faster than that of light—a violation of the laws of physics, according to Einstein. It may therefore come as a surprise that using the concept of entanglement in order to build up space-time may be a major step toward reconciling the laws of quantum mechanics and general relativity.
Tunneling to the fifth dimension
In July, physicists Juan Maldacena of the Institute for Advanced Study and Leonard Susskind of Stanford University proposed a theoretical solution in the form of two entangled black holes. When the black holes were entangled, then pulled apart, the theorists found that what emerged was a wormhole—a tunnel through space-time that is thought to be held together by gravity. The idea seemed to suggest that, in the case of wormholes, gravity emerges from the more fundamental phenomenon of entangled black holes.
Following up on work by Jensen and Karch, Sonner has sought to tackle this idea at the level of quarks—subatomic building blocks of matter. To see what emerges from two entangled quarks, he first generated quarks using the Schwinger effect—a concept in quantum theory that enables one to create particles out of nothing. More precisely, the effect, also called "pair creation," allows two particles to emerge from a vacuum, or soup of transient particles. Under an electric field, one can, as Sonner puts it, "catch a pair of particles" before they disappear back into the vacuum. Once extracted, these particles are considered entangled.
Sonner mapped the entangled quarks onto a four-dimensional space, considered a representation of space-time. In contrast, gravity is thought to exist in the next dimension as, according to Einstein's laws, it acts to "bend" and shape space-time, thereby existing in the fifth dimension.
To see what geometry may emerge in the fifth dimension from entangled quarks in the fourth, Sonner employed holographic duality, a concept in string theory. While a hologram is a two-dimensional object, it contains all the information necessary to represent a three-dimensional view. Essentially, holographic duality is a way to derive a more complex dimension from the next lowest dimension.
Using holographic duality, Sonner derived the entangled quarks, and found that what emerged was a wormhole connecting the two, implying that the creation of quarks simultaneously creates a wormhole. More fundamentally, the results suggest that gravity may, in fact, emerge from entanglement. What's more, the geometry, or bending, of the universe as described by classical gravity, may be a consequence of entanglement, such as that between pairs of particles strung together by tunneling wormholes.
"It's the most basic representation yet that we have where entanglement gives rise to some sort of geometry," Sonner says. "What happens if some of this entanglement is lost, and what happens to the geometry? There are many roads that can be pursued, and in that sense, this work can turn out to be very helpful."
by coffin_dodger » Sat Oct 18, 2014 4:28 pm
In contrast, gravity is thought to exist in the next dimension as, according to Einstein's laws, it acts to "bend" and shape space-time, thereby existing in the fifth dimension.
by DrEvil » Sat Oct 18, 2014 6:21 pm
coffin_dodger » Sat Oct 18, 2014 10:28 pm wrote:From the piece above: Creation of entanglement simultaneously gives rise to a wormholeIn contrast, gravity is thought to exist in the next dimension as, according to Einstein's laws, it acts to "bend" and shape space-time, thereby existing in the fifth dimension.
LOL - don't quite understand gravity yet, eh? - that's ok, we'll just shove in to the next dimension! Theorists have a sense of humour, it seems.
by gnosticheresy_2 » Sat Oct 18, 2014 6:33 pm
DrEvil » Sat Oct 18, 2014 7:13 pm wrote:A couple of stories that made my wild-eyed-O-meter go off the charts:
Here's the wild-eyed part, in the form of a question: If you entangle two macroscopic objects, does that create a ton of small wormholes, or one big one? And if it's a big one, could you entangle two liquids instead (Bose-Einstein condensates for instance)?
And if you can entangle two liquids, could you drop something in one and have it pop out the other?
by coffin_dodger » Sat Oct 18, 2014 6:41 pm
by DrEvil » Sat Oct 18, 2014 7:19 pm
coffin_dodger » Sun Oct 19, 2014 12:41 am wrote:Drevil - you should take a look at Walter Russell's stuff - force yourself past the 'God' bits - it's an eye-opener on accepted scientific theory.
You'll maybe see things differently, should you wish to.
).by Grizzly » Tue Oct 21, 2014 8:38 pm
by Jerky » Fri Oct 24, 2014 11:52 pm
by justdrew » Mon Oct 27, 2014 2:46 am
Conservatives and liberals really are wired differently. Scientists can accurately predict whether a subject is left-wing tree-hugger or a right-wing gun-toter based on how their brains respond to certain images, a new study in Current Biology has found.
P. Read Montague, a scientist at Virginia Tech, said his experiment was inspired by data that shows political affiliation, like height, can be inherited. "I the same sense that height is highly genetically specified, it's also true that it's not predetermined by genetics; nutrition, sleep, starvation, dramatic physical injury, and so on can serve to change one's ultimate height. However, tall people have tall children, and this is a kind of starting point [for the experiement]," he said.
Montague and his colleagues asked subjects to look at positive, negative, and disgusting images and examined functional magnetic resonance images (fMRI) of their brains. His team found that conservatives' and liberals' brains behave differently when confronted with disgusting imagery. "Disgusting images, and the mutilated body of an animal especially, generated neural responses that were highly predictive of political orientation. That was true even though the neural predictors didn't necessarily agree with participants' conscious rating of those disturbing pictures," the authors of the study said.
The test proved surprisingly accurate. "A single disgusting image was sufficient to predict each subject's political orientation," Montague said. "I haven't seen such clean predictive results in any other functional imaging experiments in our lab or others."
What the study doesn't tell us is how conservative and liberal brains differ in their response to disgusting images. Do conservatives feel revulsion, and liberals pity? We don't know. "The results do not provide a simple bromide, but they do suggest that important foundational parts of political attitudes ride on top of preestablished neural responses that may have served to defend our forebears against environmental threats," Montague said.
However, he does think that if we better understand people's ideological responses, it could change the way we do politics. "If we can begin to see that some 'knee-jerk' reactions to political issues may be simply that—reactions—then we might take the temperature down a bit in the current boiler of political discourse."
by justdrew » Mon Oct 27, 2014 3:04 am
Parallel universes – worlds where the dinosaur-killing asteroid never hit, or where Australia was colonised by the Portuguese – are a staple of science fiction. But are they real?
In a radical paper published this week in Physical Review X, we (Dr Michael Hall and I from Griffith University and Dr Dirk-André Deckert from the University of California) propose not only that parallel universes are real, but that they are not quite parallel – they can "collide".
In our theory, the interaction between nearby worlds is the source of all of the bizarre features of quantum mechanics that are revealed by experiment.
Many worlds in existing interpretations
The existence of parallel worlds in quantum mechanics is not a new idea in itself – they are a feature of one of the leading interpretations of quantum mechanics, the 1957 "many worlds interpretation" (MWI).
Now quantum mechanics is the most widely applicable and successful physical theory of all time, so you might wonder why it needs interpreting. There are two reasons.
First, its formalism is extremely remote from everyday experience. It is all based on a "wavefunction" which is like a wave, except that it lives not in ordinary three-dimensional space but in an infinite dimensional space.
Second, the so-called Bell correlations, which can be experimentally measured using distant quantum systems originating from a common source, violate the usual laws of local cause and effect.
This implies that the wavefunction formalism can't be replaced by anything in ordinary space.
There are several competing interpretations of quantum mechanics and each one gives a quite different portrayal of the ultimate nature of reality. But each portrayal is profoundly strange in some way, because of the weirdness of quantum mechanics itself.
The strangeness of the MWI is in postulating that any time any quantum system is observed in a universe, that universe "branches" into a bunch of new universes, one for each possible outcome of the observation.
The MWI has been criticised for the fact that it doesn't define precisely when an observation occurs. Thus it is vague about how many worlds there are at any given time, and each world is somewhat fuzzy in its properties, being described by a wavefunction.
Also, because different outcomes happen with different probabilities, the MWI has to postulate that different worlds have different "weights" – some worlds are more important than others even though they are all supposed to be real.
Finally, once they are created, these different worlds don't interact, so some critics say they are purely hypothetical and serve no purpose.
Many interacting worlds
Our new theory also involves many worlds but there the similarity to the standard MWI ends.
First, we postulate a fixed, although truly gigantic, number of worlds. All of these exist continuously through time – there is no "branching".
Second, our worlds are not "fuzzy" – they have precisely defined properties. In our approach, a world is specified by the exact position and velocity of every particle in that world – there is no Heisenberg uncertainty principle that applies to a single world. Indeed, if there were only one world in our theory, it would evolve exactly according to Newtonian mechanics, not quantum mechanics.
Third, our worlds do interact and that interaction is the source of all quantum effects. Specifically, there is a repulsive force of a very particular kind, between worlds with nearly the same configuration (that is, having nearly the same position for every single particle). This "interstitial" force prevents nearby worlds from ever coming to have the same configuration, and tends to make nearby worlds diverge.
Fourth, each one of our worlds is equally real. Probability only enters the theory because an observer, made up of particles in a certain world, does not know for sure which world she is in, out of the set of all worlds. Hence she will assign equal probability to every member of that set which is compatible with her experiences (which are very coarse-grained, because she is a macroscopic collection of particles). After performing an experiment she can learn more about which world she is in, and thereby rule out a whole host of worlds that she previously thought she might be in.
Putting all of the above together gives our theory – the Many Interacting Worlds approach to quantum mechanics. There is nothing else in the theory. There is no wavefunction, no special role for observation and no fundamental distinction between macroscopic and microscopic.
Nevertheless, we argue, our approach can reproduce all the standard features of quantum mechanics, including twin-slit interference, zero-point energy, barrier tunnelling, unpredictability and the Bell correlations mentioned above.
Implications and applications
We call our theory an "approach" rather than an "interpretation" because for any finite number of worlds our theory is only an approximation to quantum mechanics. This gives the exciting possibility that it might be possible to test for the existence of these other worlds.
The ability to approximate quantum evolution using a finite number of worlds could also be very useful. Specifically, it could be to model molecular dynamics, which is important for understanding chemical reactions and the action of drugs.
Quantum mechanics has always been a puzzle because of the subtle but deep ways it deviates from Newtonian mechanics. That these deviations could be due to a delicate interaction of essentially Newtonian worlds with "nearby" parallel worlds is an entirely new solution to the quantum puzzle.
For us at least there is nothing inherently implausible in the idea, and for fans of science fiction it makes those plots involving communication between parallel worlds not quite so far-fetched after all.
by elfismiles » Mon Oct 27, 2014 6:00 pm
justdrew » 27 Oct 2014 07:04 wrote:Parallel universes – worlds where the dinosaur-killing asteroid never hit, or where Australia was colonised by the Portuguese – are a staple of science fiction. But are they real?
In a radical paper published this week in Physical Review X, we (Dr Michael Hall and I from Griffith University and Dr Dirk-André Deckert from the University of California) propose not only that parallel universes are real, but that they are not quite parallel – they can "collide".
by seemslikeadream » Fri Oct 31, 2014 4:03 pm
A new type of brain cell has been discovered
FIONA MACDONALD
FRIDAY, 31 OCTOBER 2014
Researchers have described a never-before-seen brain cell shape, which appears to have evolved to transmit signals more effectively.
A strange new type of nerve cell, or neuron, has been observed in the brain that transmits information without involving the cell body - and, incredibly, it appears to be better at transmitting information than regular brain cells.
Neurons rapidly fire messages around our bodies by transmitting electrical signals to one another. Although these cells vary in shape and size, they all have the same general design: signals are received by a nerve cell’s finger-like dendrites, transmitted through its round cell body, and then passed on via the cell's long, thin axon.
However, a team led by researchers from Heidelberg University in Germany have discovered a new type of neuron in the brain, which bypasses the cell body altogether and has the axon attach directly to a dendrite.
They described the new cell in the journal Neuron at the end of September.
Just like a bypass road on a highway, this new cell shape speeds up the transmission of information to other neurons.
"Input signals at this dendrite do not need not be propagated across the cell body," Christian Thome, a neuroscientist from Heidelberg University and one of the lead authors of the study, explained in a press release.
The researchers discovered the cell in the hippocampus of mice, the brain region associated with memory. The neurons in this region are known as pyramidal cells because of their triangular cell bodies.
To investigate how the axon was connecting in these cells, the reserachers used fluorescent red protein that attached to the base of these pyramidal axons. They were expecting them to connect to the cell body, but instead were surprised that many were in fact attaching to a dendrite.
"We found that in more than half of the cells, the axon does not emerge from the cell body, but arises from a lower dendrite," said Thome.
They then tested whether these special axon-attached dendrites behaved differently to regular ones, by using a form of the neurotransmitter glutamate, a chemical released by nerve cells to transmit messages, that can be activated with light.
Using a high-resolution microscope, the scientists aimed a beam of light directly at a specific dendrite, triggering the glutamate, and activating a signal into the neuron.
They found that the dendrites connected directly to an axon responded strongly to even the smallest spike in neurotransmitter, and were therefore much better at passing a message on.
"Our measurements indicate that dendrites that are directly connected to the axon, actively propagate even small input stimuli and activate the neuron," said Tony Kelly, the co-author, from the University of Bonn, also in Germany, in the release. The researchers are calling this new method of transmitting signals ‘privileged synaptic input’.
Using a computer simulation, they found that this effect would be particularly enhanced when the messages from other dendrites was slowed down by suppressing signals in the cell body.
"That way, information transmitted by this special dendrite influences the behaviour of the nerve cell more than input from any other dendrite," said Kelly.
The next step is for them to figure out which biological functions are being sped up by these special dendrites.
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