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Distant quasars could decide whether quantum entanglement is an illusion

Distant quasars could decide whether quantum entanglement is an illusion | Amazing Science |

Strange as it may sound, physicists are planning to test whether a cosmic conspiracy could lie behind one of the weirdest phenomena in quantum physics, in which particles appear to influence each other, no matter how far they are separated. The experiment, proposed in a paper due to be published in Physical Review Letters1, would use light from distant quasars to verify that this 'entanglement' is real. The test could also help cosmologists to distinguish between rival models of the early Universe.

Entanglement is a peculiarly quantum effect that links the states of separate objects, such as elementary particles, so that when one of the states is measured the properties of its twin are immediately affected. The notion that the particles influence each other faster than the speed of light famously galled Einstein, who argued instead that there could be some 'hidden variables' that influence the particles' behaviour in experiments, in line with classical physics.

Entanglement has been demonstrated in countless experiments starting in the 1970s, but a loophole could still invalidate the conclusion that the quantum explanation is correct: if hidden variables exist, then it is possible that they could influence the testing apparatus to give the illusion that correlations are more common than they are. This would require the history of the Universe to be pre-ordained to give scientists the illusion that they have complete freedom in how they set up their measurement, whereas in fact they do not.

In 2010, quantum physicist Anton Zeilinger of the University of Vienna and colleagues carried out a test that ruled out the possibility that hidden variables created during the experiment could have conspired with the detection apparatus2. “But that left open the possibility that a conspiracy was set up further back in time, even just a few milliseconds before the experiment began,” says Andrew Friedman, a cosmologist at the Massachusetts Institute of Technology in Cambridge and a coauthor of the current paper.

To minimize the risk of a conspiracy, both Zeilinger’s and Friedman’s teams are looking to the skies — in particular at light coming from energetic cosmic objects known as quasars. The plan is to set up a standard entanglement test in the laboratory. While it is running, the researchers will also measure light coming from two quasars on opposite sides of the sky. On the basis of, for instance, whether the light from the first quasar hits their telescope at an even or an odd nanosecond, they would then make a decision about which two properties of their first entangled particle to observe. They would similarly decide what measurements to make on the second entangled particle, on the basis of the arrival time of the light from the second quasar.

Quasars far enough apart would have formed in regions that have never been able to influence each other since the first fractions of a second after the Big Bang, some 13.8 billion years ago. If the results once again favour the quantum interpretation, the experiment would push the point in time at which any hidden-variable conspiracy could have occurred “far further back than it ever has been before”, says Zeilinger: to the beginning of the Universe itself.

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Is the Universe a Simulation and are there Ways to Test it?

Is the Universe a Simulation and are there Ways to Test it? | Amazing Science |
If so, that would help explain some mysterious things about math.

Mathematical knowledge is unlike any other knowledge. Its truths are objective, necessary and timeless. What kinds of things are mathematical entities and theorems, that they are knowable in this way? Do they exist somewhere, a set of immaterial objects in the enchanted gardens of the Platonic world, waiting to be discovered? Or are they mere creations of the human mind?

This question has divided thinkers for centuries. It seems spooky to suggest that mathematical entities actually exist in and of themselves. But if math is only a product of the human imagination, how do we all end up agreeing on exactly the same math? Some might argue that mathematical entities are like chess pieces, elaborate fictions in a game invented by humans. But unlike chess, mathematics is indispensable to scientific theories describing our universe. And yet there are many mathematical concepts — from esoteric numerical systems to infinite-dimensional spaces — that we don’t currently find in the world around us. In what sense do they exist?

Many mathematicians, when pressed, admit to being Platonists. The great logician Kurt Gödel argued that mathematical concepts and ideas “form an objective reality of their own, which we cannot create or change, but only perceive and describe.” But if this is true, how do humans manage to access this hidden reality?

We don’t know. But one fanciful possibility is that we live in a computer simulation based on the laws of mathematics — not in what we commonly take to be the real world. According to this theory, some highly advanced computer programmer of the future has devised this simulation, and we are unknowingly part of it. Thus when we discover a mathematical truth, we are simply discovering aspects of the code that the programmer used.

This may strike you as very unlikely. But the Oxford philosopher Nick Bostrom has argued that we are more likely to be in such a simulation than not. If such simulations are possible in theory, he reasons, then eventually humans will create them — presumably many of them. If this is so, in time there will be many more simulated worlds than nonsimulated ones. Statistically speaking, therefore, we are more likely to be living in a simulated world than the real one.

Very clever. But is there any way to empirically test this hypothesis? Indeed, there may be. In a recent paper, “Constraints on the Universe as a Numerical Simulation,” the physicists Silas R. Beane, Zohreh Davoudi and Martin J. Savage outline a possible method for detecting that our world is actually a computer simulation. Physicists have been creating their own computer simulations of the forces of nature for years — on a tiny scale, the size of an atomic nucleus. They use a three-dimensional grid to model a little chunk of the universe; then they run the program to see what happens. This way, they have been able to simulate the motion and collisions of elementary particles.

But these computer simulations, Professor Beane and his colleagues observe, generate slight but distinctive anomalies — certain kinds of asymmetries. Might we be able to detect these same distinctive anomalies in the actual universe, they wondered? In their paper, they suggest that a closer look at cosmic rays, those high-energy particles coming to Earth’s atmosphere from outside the solar system, may reveal similar asymmetries. If so, this would indicate that we might — just might — ourselves be in someone else’s computer simulation.

Are we prepared to take the “red pill,” as Neo did in “The Matrix,” to see the truth behind the illusion — to see “how deep the rabbit hole goes”? Perhaps not yet. The jury is still out on the simulation hypothesis. But even if it proves too far-fetched, the possibility of the Platonic nature of mathematical ideas remains — and may hold the key to understanding our own reality.

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Beyond the horizon of the cosmos: Is there more than one universe?

Beyond the horizon of the cosmos: Is there more than one universe? | Amazing Science |

Together with Tomo Takahashi and Richard Holman, Laura Mersini-Houghton published a series of papers in 2006 called “Avatars of the Landscape” making concrete, empirical predictions for the signatures of other universes on ours. Most importantly, this group demonstrated that the early entanglement of our universe with the rest of the "multiverse" added an independent source of variation to the strength of the Cosmic Microwave Background (CMB), a detailed fingerprint that allows astronomers to cast their gaze onto the first few moments of our universe’s existence. and to the distribution of matter around our universe, known as structure. In addition, the team calculated the strength of the entanglement and showed that its effect should be observable at large scales.

When they published their work, they didn’t dream that these predictions would be confirmed within their lifetimes. Amazingly, eight of the nine predictions were tested within a scant seven years, and all were in agreement with the data. Just last year, the Planck satellite data successfully tested seven of these predictions in one fell swoop.

The absence of Supersymmetry (SUSY) breaking at energies of about 1 trillion electron volts was confirmed by the Large Hadron Collider, in agreement with the ninth prediction. Only the Dark Flow prediction is still under debate, with two Planck team papers drawing conflicting conclusions. Taken together, these nine predictions represent a very stringent test of the theory, because all nine originate from a single theoretical framework. None of these predictions can be varied independently of the other eight in order to fit a particular set of data – the data must confirm them all, or the theory is ruled out.

Two previous measurements of the cosmic microwave background (COBE in 1992 and WMAP in 2007) have observed anomalies like those measured by Planck, but at a lower level of confidence. It may still turn out that the Planck anomalies are overestimated. If that turns out to be the case we will be back to square one. But if the anomalies are confirmed, and with it our first glimpse of the multiverse, astronomers will have achieved something remarkable. Not only will they have found evidence for other universes, they will also have found the first tests of string theory, whose description of the landscape important for cosmology. More broadly, the existence of multiple universes will demand to revisit and confront some of the most cherished notions about the cosmos and develop a new view of reality: do all universes live on the same underlying space-time fabric? Was there a notion of time before our Big Bang? Can we detect universes that are not entangled with ours? What determines the laws of nature? It will be an exciting time.

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For the first time, astronomers discover a black hole orbiting a spinning star

For the first time, astronomers discover a black hole orbiting a spinning star | Amazing Science |
There's a star about 8,500 light-years away that's spinning so fast its surface speed exceeds 620,000 mph. Astronomers are familiar with these kinds of stars, but this one's wholly unique in that it has a rather strange companion: a black hole.

To date, astronomers have catalogued more than 80 of these Be type stars. They're typically members of a binary system, with the companion being a neutron star (collapsed stars that aren't big enough to form black holes). Amazingly, Be stars can spin at these horrendous speeds without breaking-up, producing huge centrifugal forces. The Be star in question, MWC 656, was first discovered in 2010. But Spanish researchers now say there's a black hole spinning around it.

A detailed analysis of its spectrum allowed scientists to infer the characteristics of its companion. "It turned out to be an object with a mass between 3.8 and 6.9 solar masses," said Ignasi Ribas of CSIC at the Institute of Space Sciences. "An object like that, invisible to telescopes and with such large mass, can only be a black hole because no neutron star with more than three solar masses can exist."

The black hole orbits the more massive Be star and is fed by matter ejected from the latter. "The high rotation speed of the Be star causes matter to be ejected into an equatorial disk," said Ignacio Negueruela at the University of Alicante. "This matter is attracted by the black hole and falls on to it, forming another disk, called an accretion disk. By studying the emission from the accretion disk, we could analyze the motion of the black hole and measure its mass."

The astronomers think it's a member of a hidden population of Be stars paired with black holes and that they're more common than previous thought. Unfortunately, they're hard to detect because their black holes are fed from gas ejected by the Be stars without producing much radiation.


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Massive galaxy cluster verifies kinetic Sunyaev-Zel'dovich effect

Massive galaxy cluster verifies kinetic Sunyaev-Zel'dovich effect | Amazing Science |

By observing a high-speed component of a massive galaxy cluster, Caltech/JPL scientists and collaborators have detected for the first time in an individual object the kinetic Sunyaev-Zel'dovich effect, a change in the cosmic microwave background caused by its interaction with massive moving objects.

MACS J0717.5+3745 is an extraordinarily dynamic galaxy cluster with a total mass greater than 1015 (a million billion) times the mass of the sun or more than 1,000 times the mass of our own galaxy. It appears to contain three relatively stationary subclusters (A, C, and D) and one subcluster (B) that is being drawn into the larger galaxy cluster, moving at a speed of 3,000 kilometers per second.

The galaxy cluster was observed by a team led by Sunil Golwala, professor of physics at Caltech and director of the Caltech Submillimeter Observatory (CSO) in Hawaii. Subcluster B was observed during what appears to be its first fall into MACS J0717.5+3745. Its momentum will carry it through the center of the galaxy cluster temporarily, but the strong gravitational pull of MACS J0717.5+3745 will pull subcluster B back again. Eventually, subcluster B should settle in with its stationary counterparts, subclusters A, C, and D.

Though subcluster B's behavior is dramatic, it fits neatly within the standard cosmological model. But the details of the observations of MACS J0717.5+3745 at different wavelengths were puzzling until they were analyzed in terms of a theory called the kinetic Sunyaev-Zel'dovich (SZ) effect.

In 1972, two Russian physicists, Rashid Sunyaev and Yakov Zel'dovich, predicted that we should be able to see distortions in the cosmic microwave background (CMB)—the afterglow of the Big Bang—whenever it interacts with a collection of free electrons. These free electrons are present in the intracluster medium, which is made up primarily of gas. Gas within dense clusters of galaxies is heated to such an extreme temperature, around 100 million degrees, that it no longer coheres into atoms. According to Sunyaev and Zel'dovich, the photons of the CMB should be scattered by the high-energy electrons in the intracluster medium and take on a measurable energy boost as they pass through the galaxy cluster.

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Simulations back up theory that Universe is a hologram

Simulations back up theory that Universe is a hologram | Amazing Science |
A ten-dimensional theory of gravity makes the same predictions as standard quantum physics in fewer dimensions.

At a black hole, Albert Einstein's theory of gravity apparently clashes with quantum physics, but that conflict could be solved if the Universe were a holographic projection. A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection. 

In 1997, theoretical physicist Juan Maldacena proposed1 that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.

Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a 'duality', that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.

In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true. In one paper2, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence. In the other3, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match. “It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, New Jersey and who did not contribute to the team's work.

The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”

“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture — namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.

Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.

Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.


  1. Hyakutake, Y. (2013).

  2. Hanada, M., Hyakutake, Y., Ishiki, G. & Nishimura, J. (2013).

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Holographic Dual of an Einstein-Podolsky-Rosen Pair shows "spooky action" through a wormhole

Holographic Dual of an Einstein-Podolsky-Rosen Pair shows "spooky action" through a wormhole | Amazing Science |

Quantum entanglement is weird enough, but it might get weirder still through a possible association with hypothetical wormholes. Over the past year, theorists have been hard at work exploring the entanglement of two black holes. A pair of papers in Physical Review Letters advances the story by showing that a string-based representation of two entangled quarks is equivalent to the spacetime contortions of a wormhole.


A common feature of entanglement and wormholes is that they both seemingly imply faster-than-light travel. If one imagines two entangled particles separated by a large distance—a so-called Einstein-Podolsky-Rosen (EPR) pair—then a measurement of one has an immediate effect on the measurement probabilities of the other, as if information travels instantaneously between them. Similarly, a wormhole—or Einstein-Rosen (ER) bridge—is a “shortcut” connecting separate points in space, but no information can actually pass through. Recent work has shown that the spacetime geometry of a wormhole is equivalent to what you’d get if you entangled two black holes and pulled them apart—an equivalence that can be summarized by “ER = EPR.”


The latest papers in this development extend the equivalence beyond black holes to quarks. As previous studies have shown, two entangled quarks can be represented as the endpoints of a string in a higher dimensional space, where certain calculations end up being easier.


Kristan Jensen of the University of Victoria, Canada, and Andreas Karch of the University of Washington, Seattle, imagine the entangled quarks are accelerating away from each other, so that they are no longer in causal contact. In this case, the connecting string becomes mathematically equivalent to a wormhole. Using a different approach, Julian Sonner from the Massachusetts Institute of Technology, Cambridge, has derived the same result starting from quark/antiquark creation in a strong electric field (the Schwinger effect).


The wormhole connection may provide new insights into entanglement, as suggested by calculations that equate the entropy of the wormhole to that of the quarks.

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3D Cosmography of the Local Universe - a film by Hélène Courtois

The large scale structure of the universe is a complex web of clusters, filaments, and voids. Its properties are informed by galaxy redshift surveys and measurements of peculiar velocities. Wiener Filter reconstructions recover three-dimensional velocity and total density fields. The richness of the elements of our neighborhood are revealed with sophisticated visualization tools.

The ability to translate and zoom helps the viewer follow structures in three dimensions and grasp the relationships between features on different scales while retaining a sense of orientation. The ability to dissolve between scenes provides a technique for comparing different information, for example, the observed distribution of galaxies, smoothed representations of the distribution accounting for selection effects, observed peculiar velocities, smoothed and modeled representations of those velocities, and inferred underlying density fields.

The agreement between the large scale structure seen in redshift surveys and that inferred from reconstructions based on the radial peculiar velocities of galaxies strongly supports the standard model of cosmology where structure forms from gravitational instabilities and galaxies form at the bottom of potential wells.

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Farthest confirmed galaxy is a prolific star creator

Farthest confirmed galaxy is a prolific star creator | Amazing Science |

Astronomers have measured the distance of the farthest known galaxy, finding that its light took 13.1 billion years to reach Earth – which means the light was emitted just 700 million years after the Big Bang. Although the galaxy is much smaller than the Milky Way, it is forming stars at a much faster rate. The discovery provides important new information about the epoch of reionization, the ancient era when the neutral gas between galaxies became ionized.


To observe the farthest galaxies, astronomers exploit the universe's expansion, which stretches – or redshifts – the light waves of distant objects to longer, or redder, wavelengths. But dust can also redden light, so a red colour alone does not guarantee that a galaxy lies at the edge of the observable universe.


"The problem had been, over the previous few years, [that] people have been trying to confirm these really distant galaxies – and for the most part coming up empty," says Steven Finkelstein, an astronomer at the University of Texas at Austin.


Confirmation of a far-off galaxy's distance requires measuring the redshift of lines in the spectrum of light that it emits. This means that astronomers face the challenge of obtaining the spectrum of a faint object. So for two nights in April, Finkelstein took aim at 43 red objects in the constellation Ursa Major with one of the largest telescopes in the world, the 10-metre Keck I telescope atop Mauna Kea in Hawaii. A year earlier, this telescope had received a more sensitive spectrograph, which made Finkelstein's observations possible.


Finkelstein searched the spectra for a line from Lyman-alpha emission. This radiation arises when an electron falls from the n = 2 to the n = 1 state of hydrogen, which is the most abundant element in the cosmos. This spectral line normally emits far-ultraviolet radiation at a wavelength of 1216 Å (121.6 nm), but because of the hoped-for redshifts, Finkelstein obtained his spectra at near-infrared wavelengths instead.


In 42 of the 43 spectra, Finkelstein saw no lines. "I was disappointed, I think – until I figured out the redshift of the one we did see and realized it was the most distant one." That galaxy, bearing the unwieldy name z8_GND_5296, has a Lyman-alpha line at a wavelength of 10,343 Å (1.0343 μm), a 751% increase over the rest wavelength, which means that the galaxy's redshift is 7.51. It is 40 million light-years more remote than the previous record holder, at redshift 7.215.

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Herschel helps to find elusive signals from the early Universe

Herschel helps to find elusive signals from the early Universe | Amazing Science |

Using a telescope in Antarctica and ESA’s Herschel space observatory, astronomers have made the first detection of a subtle twist in the relic radiation from the Big Bang, paving the way towards revealing the first moments of the Universe’s existence.


The elusive signal was found in the way the first light in the Universe has been deflected during its journey to Earth by intervening galaxy clusters and dark matter, an invisible substance that is detected only indirectly through its gravitational influence.


The discovery points the way towards finding evidence for gravitational waves born during the Universe’s rapid ‘inflation’ phase, a crucial result keenly anticipated from ESA’s Planck mission.


The relic radiation from the Big Bang – the Cosmic Microwave Background, or CMB – was imprinted on the sky when the Universe was just 380 000 years old. Today, some 13.8 billion years later, we see it as a sky filled with radio waves at a temperature of just 2.7 degrees above absolute zero.


Tiny variations in this temperature – around a few tens of millionths of a degree – reveal density fluctuations in the early Universe corresponding to the seeds of galaxies and stars we see today. The most detailed all-sky map of temperature variations in the background was revealed by Planck in March.


But the CMB also contains a wealth of other information. A small fraction of the light is polarised, like the light we can see using polarised glasses. This polarised light has two distinct patterns: E-modes and B-modes.


E-modes were first found in 2002 with a ground-based telescope. B-modes, however, are potentially much more exciting to cosmologists, although much harder to detect.


They can arise in two ways. The first involves adding a twist to the light as it crosses the Universe and is deflected by galaxies and dark matter – a phenomenon known as gravitational lensing.


The second has its roots buried deep in the mechanics of a very rapid phase of enormous expansion of the Universe, which cosmologists believe happened just a tiny fraction of a second after the Big Bang – ‘inflation’.


The new study has combined data from the South Pole Telescope and Herschel to make the first detection of B-mode polarisation in the CMB due to gravitational lensing.


“This measurement was made possible by a clever and unique combination of ground-based observations from the South Pole Telescope – which measured the light from the Big Bang – with space-based observations from Herschel, which is sensitive to the galaxies that trace the dark matter which caused the gravitational lensing,” says Joaquin Vieira, of the California Institute of Technology and the University of Illinois at Urbana-Champaign, who led the Herschel survey used in the study.

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Standard Candle' Supernova Extraordinarily Magnified by Gravitational Lensing

Standard Candle' Supernova Extraordinarily Magnified by Gravitational Lensing | Amazing Science |

A team of researchers at the Kavli IPMU led by Robert Quimby has identified what may prove to be the first ever Type Ia supernova (SNIa) magnified by a strong gravitational lens.


In this work, the 'standard candle' property of Type Ia supernovae is used to directly measure the magnification due to gravitational lensing. This provides the first glimpse of the science that will soon come out of dark matter and dark energy studies derived from deep, wide-field imaging surveys. The supernova, named PS1-10afx, was discovered by the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1).


PS1-10afx exploded over 9 billion years ago, which places it far further than typical Pan-STARRS1 discoveries. Based on this distance and its relatively bright appearance, the Pan-STARRS1 team concluded that PS1-10afx was intrinsically very luminous.


The inferred luminosity, about 100 billion times greater than our Sun, is comparable to members of a new, rare variety of superluminous supernovae (SLSNe), but that is where the similarities end.


SLSNe typically have blue colors, and their brightness changes relatively slowly with time. PS1-10afx on the other hand was rather red even after correcting for its redshift, and its brightness changed as fast as normal supernovae. There is no known physical model that can explain how a supernova could simultaneously be so luminous, so red, and so fast.

Soon after the findings were announced, Robert Quimby, a postdoctoral researcher at Kavli IPMU, independently analyzed the data. Quimby is an expert in SLSNe and has played a key role in their discovery. He quickly confirmed part, but not all of the conclusions.


PS1-10afx was indeed rather distinct from all known SLSNe, but the data struck Quimby as oddly familiar. He compared the features seen in the spectra of PS1-10afx to known supernova, and, surprisingly, found an excellent match. The spectra of PS1-10afx are almost identical to normal SNIa.


SNIa have a very useful property that has enabled cosmologists to chart the expansion of our Universe over the last several billion years: SNIa have strikingly similar peak luminosities that can be rendered even more standard by correcting for how quickly they brighten and fade (their "light curves").


This property allows astronomers to use SNIa as standard candles to measure distances, as was key to the discovery of the accelerating expansion of the Universe (2011 Nobel Prize in Physics).

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Quantum black hole study opens bridge to another universe

Quantum black hole study opens bridge to another universe | Amazing Science |

Physicists have long thought that the singularities associated with gravity (like the inside of a black hole) should vanish in a quantum theory of gravity. It now appears that this may indeed be the case. Researchers in Uruguay and Louisiana have just published a description of a quantum black hole using loop quantum gravity in which the predictions of physics-ending singularities vanish, and are replaced by bridges to another universe. Singularities, such as the infinitely strong crushing forces at the center of a black hole, in a physical theory are bad. What they tell you is that your description of the universe fails miserably to explain what happens as you approach the singularity. Tricks can sometimes resolve what appears to be singular behavior, but essential singularities are signs of a failure of the physical description itself.


General relativity has been summed up by the late John Wheeler's phrase: "Spacetime tells matter how to move, matter tells spacetime how to curve." Relativity is riddled with essential singularities, because gravity is both attractive and nonlinear – curvature in the presence of mass tends to lead to more curvature, eventually leading to trouble.


The result is rather similar to a PA system on the verge of producing a feedback whistle. If you whisper into the microphone (small gravitational fields) the positive feedback isn't enough to send the PA into oscillation, but talking at a normal volume (larger gravitational fields) produces that horrible howl. Whispering is the comparable to the familiar actions of gravity that keep the planets and stars in their courses. The howl is the process that eventually leads to a singularity as the end result of gravitational collapse.


Let's follow this analogy a bit further. On a PA system, the volume of the feedback is limited by the power capacity of the amplifier, so it can't reach truly destructive levels (other than to our eardrums.) However, gravity as described by general relativity doesn't have such a limit. Since gravity is always attractive, and eventually becomes stronger than all the (known) forces that normally give volume to matter, there is nothing to keep gravitational collapse from proceeding until the curvature of the spacetime tends toward infinity – i.e. a singularity.


Remember that this is the prediction of the classical theory of gravity, general relativity. Classical physical theories contain no fundamental limitation on mass-energy density or on the size of spacetime curvature. While this may be (and probably is) incorrect, we rarely run into a problem caused by this error, so have largely ignored the problem for centuries.


Then along came gravitational collapse and black holes. First proposed by geologist John Mitchell in 1783, a black hole is a region of spacetime from which gravity prevents anything, even light, from escaping.


Black holes are formed when large stars run out of fuel. When a star's core cools, the star shrinks. As the star's layers fall inward, they are compressed by the unbalanced force of gravity, and heat up until a new balance is established. This can only go on so long, as the star (on average) gets smaller at each step of the process of collapse. Eventually the heating driven by this gravitational collapse becomes too small to hold the star up.


At this point, the size of the star depends mostly on its mass, as the force of gravity is only balanced by the ability of the star's material to resist pressure. If a star is heavy enough (8-10 times the mass of our Sun), there is no known source of material pressure which is large enough to resist gravity. In that case, the star collapses without end, and forms a black hole, from which even light cannot escape.


Black holes really began to be understood in the late 1950s, when David Finkelstein, then a professor at the Stevens Institute of Technology, found that the odd behavior at the Schwartzchild radius was actually "... a perfect unidirectional membrane: causal influences can cross it but only in one direction." In other words, what falls into a black hole stays there.

Via Chuck Sherwood, Senior Associate, TeleDimensions, Inc, John Purificati
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Anomalies in relic radiation: Universe may be curved, not flat

Anomalies in relic radiation: Universe may be curved, not flat | Amazing Science |

Anomalies in relic radiation could contradict the evidence for a level cosmos. 


We live in a lopsided universe: That has been a lesson that cosmologists have learned from examining the detailed structure of the radiation left over from the Big Bang. Now, two cosmologists show that the data are consistent with a Universe that is curved slightly, similarly to a saddle. If their model is correct, it would overturn the long-held belief that the cosmos is flat.


On a large scale, precision measurements of the cosmic microwave background (CMB) by NASA’s Wilkinson Microwave Anisotropy Probe provided the first hints of an asymmetry in 2004. Some experts wondered whether the finding was a systematic error that would be corrected when the NASA probe’s successor, the European Space Agency’s Planck spacecraft, mapped the CMB again with higher precision. But the Planck results, announced earlier this year, confirmed the anomaly.


To explain those results, Andrew Liddle and Marina Cortês, both at the University of Edinburgh, UK, have now proposed a model of cosmic inflation — a hypothetical period of rapid expansion right after the Big Bang in which the Universe grew by many orders of magnitude in a small fraction of a second.


The simplest theory of inflation holds that the Universe is flat and that its expansion is driven by a single quantum field called the inflaton. In this model the inflaton has two roles: it triggers hyperexpansion and generates the tiny density fluctuations that enlarged to become the seeds of galaxies.


But this version of inflation cannot account for the Universe’s lopsidedness except as a statistical fluke — similar to, for example, a fair coin that happens to come up heads many more times than tails over 1,000 flips. If the CMB anomalies are not flukes, they could offer an unprecedented window on the detailed structure of the early universe, says Liddle.


Like many theorists before them, Liddle and Cortês invoke a second quantum field — the curvaton — to set the primordial density fluctuations in the infant Universe, restricting the inflaton to driving the era of hyperexpansion only.

The researchers show that the curvaton field would generate the lopsided density fluctuations that have been observed if space had a slightly negative curvature on large scales. This means that if large triangles could be ‘drawn’ in space, their internal angles would add up to less than 180 degrees. In a flat Universe the angles would add up to 180 degrees exactly, and in a positively curved one they would add up to more than 180 degrees.


In Liddle and Cortês’s scenario, the asymmetry of the CMB would derive from a lack of uniformity on the very large scale of the Universe encoded in the curvaton field. In 2008, Erickcek and her colleagues proposed a similar mechanism. That model, however, did not invoke a negatively curved Universe.


Although numerous observations indicate that the cosmos is indeed flat, the deviations in the CMB data predicted by latest model — which the authors acknowledge is still speculative — could be small enough to fit within the limits imposed by measurements with the Planck satellite, says Liddle. Future experiments with measurements of improved precision however might determine who is right.

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Cosmic mismatch hints at the existence of a fourth type of neutrino

Cosmic mismatch hints at the existence of a fourth type of neutrino | Amazing Science |

Neutrinos, some of the most abundant particles in the universe, are also among the most mysterious. We know they have mass but not how much. We know they come in at least three types, or 'flavors' — but there may be more. A new study found that a mismatch between observations of galaxy clusters and measurements of the cosmic background radiation could be explained if neutrinos are more massive than is usually thought. It also offers tantalizing hints that a fourth type of hitherto unseen neutrino exists.

The tension between galaxy clusters and the cosmic microwave background (CMB) has been a brewing problem, albeit one that might be resolved simply by getting better measurements in the coming years (see 'Missing galaxy mass found'). The background radiation shows the small density variations in the early universe that would eventually cause matter to clump in some places and form voids in others. We can see the end product of this clumping in the recent universe by observing the spread of galaxy clusters across space.

Theorists have long suggested that a fourth type of neutrino might exist, but so far proof of them has been elusive. Hints at some particle accelerator experiments2 lately have begun to suggest they are out there, however. "What's really interesting is that the mass of this sterile neutrino, is consistent with what the other experiments see," says physicist Joseph Formaggio of the Massachusetts Institute of Technology in Cambridge. "I think people are starting to look at the data and say maybe there's something there." And coincidentally another study3 supporting the idea of a sterile neutrino as well as heavier neutrino masses was also published in the same issue of PRL.

For many years neutrinos were thought to be completely massless, but the discovery that they can swap flavors also proved that they have at least a little bit of mass. Each flavor’s state is thought to be a mixture of the three unknown neutrino masses — called mass 1, mass 2 and mass 3 for the time being — and this mixing is why any flavor has a chance of turning into one of the other flavors over time. The transformation is only possible if the mass states are different from one another, and such a difference is only possible if neutrinos' mass is nonzero, Formaggio explains.

Experiments aiming to catch neutrinos in the act of switching flavours could help pin down the differences between the neutrino masses and tell us which weighs more—the so-called neutrino-mass hierarchy. One such experiment, called NuMI Off-Axis νe Appearance (NOvA), measured its first neutrinos last week. The experiment creates a beam of neutrinos at the Fermi National Accelerator Laboratory (Fermilab) near Chicago and sends them to two detectors — one near Fermilab and another 800 kilometres away in Ash River, Minnesota. All of the particles start as muon neutrinos but some precious few arrive at the distant detector having turned into electron neutrinos, which create a different signature. The frequency at which this happens is related to the difference between electron and muon neutrinos' masses.

Another experiment based in Japan called the Japanese Tokai to Kamioka (T2K) project also looks for these transformations. The collaboration announced last week that it had observed a record total of 28 candidate mutations from muon into electron neutrinos, with only about five of the events predicted to be other processes masquerading as the real thing. It is the strongest evidence to date for this type of neutrino oscillation, although much more data will be needed to answer questions about neutrinos' masses. "It's sort of like a big mile marker in a long race," says Formaggio, who wrote an essay accompanying the publication of the result on 10 February in PRL. The two experiments are complementary, says NOvA deputy project leader Rick Tesarek. "There are some capabilities that NOvA has that T2K doesn’t have" and vice versa. The experiments use different detector technology that is sensitive to different effects, and the NOvA project has a longer distance between its neutrino beam and the far detectors.

As these experiments gather more data the secrets of neutrino masses may be revealed. The coming years should also clarify whether galaxy cluster measurements are truly incompatible with the cosmic background radiation data, and hence whether they point toward heavier neutrino masses and/or a sterile neutrino.

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Making predictions about the multiverse

Making predictions about the multiverse | Amazing Science |

A recent conference organized by the Fundamental Questions Institute (FQXi) in Puerto Rico about making predictions in cosmology, especially in the eternally inflating multiverse. Many physicists and cosmologists are thinking with some “confidence” that we live in a multiverse, more specifically one of the many universes in which low-energy physical laws take different forms. For example, these universes have different elementary particles with different properties, possibly different spacetime dimensions, and so on. This idea of the multiverse is not simply a result of random imagination by theorists, but is based on several pieces of observational and theoretical evidence.

Observationally, we have learned more and more that we live in a highly special universe—it seems that the “physical laws” of our universe (summarized in the form of standard models of particle physics and cosmology) takes such a special form that if its structure were varied slightly, then there would be no interesting structure in the universe, let alone intelligent life. It is hard to understand this fact unless there are many universes with varying “physical laws,” and we simply happen to emerge in a universe which allows for intelligent life to develop (which seems to require special conditions). With multiple universes, we can understand the “specialness” of our universe precisely as we understand the “specialness” of our planet Earth (e.g. the ideal distance from the sun), which is only one of the many planets out there.

Perhaps more nontrivial is the fact that our current theory of fundamental physics leads to this picture of the multiverse in a very natural way. Imagine that at some point in the history of the universe, space is exponentially expanding. This expansion—called inflation—occurs when space is filled with a “positive vacuum energy”, which happens quite generally. We knew, already in 80′s, that such inflation is generically eternal. During inflation, various non-inflating regions called bubble universes—of which our own universe could be one—may form, much like bubbles in boiling water. Since ambient space expands exponentially, however, these bubbles do not percolate; rather, the process of creating bubble universes lasts forever in an eternally inflating background. Now, recent progress in string theory suggests that low energy theories describing phyics in these bubble universes (such as the elementary particle content and their properties) may differ bubble by bubble. This is precisely the setup needed to understand the “specialness” of our universe because of the selection effect associated with our own existence, as described above.

This particular version of the multiverse—called the eternally inflating multiverse—is very attractive. It is theoretically motivated and has a potential to explain various features seen in our universe. The eternal nature of inflation, however, causes a serious issue of predictivity. Because the process of creating bubble universes occurs infinitely many times, “In an eternally inflating universe, anything that can happen will happen; in fact, it will happen an infinite number of times,” as phrased in an article by Alan Guth.

The picture presented here does not solve all the problems in eternally inflating cosmology. What is the actual quantum state of the multiverse? What is its “initial conditions”? What is time? How does it emerge? The basic idea is that the state of the multiverse (which may be selected uniquely by the normalizability condition) never changes, and yet time appears as an emergent concept locally in branches as physical correlations among objects (along the lines of an old idea by DeWitt). 

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Planck Star: A New Type of Star Emerges From Inside Black Holes

Planck Star: A New Type of Star Emerges From Inside Black Holes | Amazing Science |

Black holes have fascinated scientists and the public alike for decades. There is special appeal in the idea that the universe contains regions of space so dense that light itself cannot escape and so extreme that the laws of physics no longer apply. What secrets can these extraordinary objects hide?

Today, we get an answer thanks to the work of Carlo Rovelli at the University of Toulon in France, and Francesca Vidotto at Radboud University in the Netherlands. These guys say that inside every black hole is the ghostly, quantum remains of the star from which it formed. And that these stars can later emerge as the black hole evaporates.

Rovelli and Vidotto call these objects “Planck stars” and say they could solve one of the most important questions in astrophysics. What’s more, evidence for the existence of Planck stars may be readily available, simply by looking to the night sky.

Planck stars would be small— stellar-mass black hole would form a Planck star about 10^-10 centimetres in diameter. But that’s still some 30 orders of magnitude larger than the Planck length.

An interesting question is whether these Planck stars would be stable throughout the life of the black hole that surrounds them. Rovelli and Vidotto have a fascinating answer. They say that the lifetime of a Planck star is extremely short, about the length of time it takes for light to travel across it.

But to an outside observer, Planck stars would appear to exist much longer. That’s because time slows down near high-density masses. For such an observer, a Planck star would last just as long as its parent black hole.

It then becomes possible for the black hole to interact with the Planck star it contains. Rovelli and Vidotto point out that as the black hole evaporates and shrinks, its boundary will eventually meet that of the Planck star as it expands after the bounce. “At this point there is no horizon any more and all information trapped inside can escape,” they say.

That immediately solves the information paradox. The information isn’t lost or trapped inside an unimaginably small region of space but eventually re-emitted into the universe.

There’s yet another exciting consequence of these ideas. Rovelli and Vidotto say this release of information would generate radiation with a wavelength of about 10^-14 cm. In other words, gamma rays.

The universe is filled with a foggy background of gamma rays that astrophysicists have already observed in considerable detail with orbiting telescopes. Could it be that they have already detected the signature of Planck stars releasing their information into the cosmos?

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Triple star system might reveal secrets of gravity

Triple star system might reveal secrets of gravity | Amazing Science |

Astronomers have discovered a unique triple star system which could reveal the true nature of gravity. They found a pulsar with two white dwarfs all packed in a space smaller than Earth's orbit of the Sun.

The trio's unusually close orbits allow precise measurements of gravity and could resolve difficulties with Einstein's theories. The results appear in Nature journal and will be presented at the 223rd American Astronomical Society meeting.

"This triple system gives us a natural cosmic laboratory far better than anything found before for learning exactly how such three-body systems work and potentially for detecting problems with general relativity that physicists expect to see under extreme conditions," said Scott Ransom of the US National Radio Astronomy Observatory (NRAO) in Charlottesville, VA.

"This is a fascinating system in many ways, including what must have been a completely crazy formation history, and we have much work to do to fully understand it."

Pulsars emit lighthouse-like beams of radio waves that rapidly sweep through space as the stars spin on their axes. They are formed after a supernova collapses a burnt-out star to a dense, highly magnetised ball of neutrons. Using the Green Bank Telescope, the astronomers discovered a pulsar 4,200 light-years from Earth, spinning nearly 366 times per second.

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Astrophysicist suggests a very brief habitable epoch of the early Universe just after big bang

Astrophysicist suggests a very brief habitable epoch of the early Universe just after big bang | Amazing Science |

Theoretical astrophysicist Abraham Loeb of Harvard University has uploaded a paper he's written to the preprint server arXiv, in which he suggests that conditions shortly after the Big Bang may have been just right for life to appear in some parts of the universe—for just a short time.

Loeb notes that according to theory, 15 million years after the Big Bang, the entire universe would have been warm enough to support life due to the cooling of superheated gases that eventually led to what scientists believe is cosmic microwave background (CMB). Today, it's very cold of course, (2.7 Kelvin), but not long, relatively speaking, after the Big Bang, the temperature would have been closer to 300 Kelvin—more than warm enough to support life if there were a place for it to appear. And that Loeb suggests, might have been possible as well. He notes that it would have been possible for rocky planets to have existed at that time too—in places where matter was exceptionally dense. Because of that, he believes it's possible that all of the pieces necessary for the appearance of life might have been in place in some parts of the universe, for approximately two or three million years—enough time for the initial brewing that could have led to the development of microbes of some sort.

Of course, if it did happen, that life would not have lived long enough (2 to 3 million years) to evolve into anything complex—it would have been snuffed out as the CMB cooled—happening as it would have before stars would have had enough time to form and emit heat of their own. Thus, no evidence would have been left behind, which means Loeb's theory can never be proven. If it could, that might upset another principle regarding the universe—the anthropic principle—which suggests that all of the things that needed to happen in the universe for us to be here today to observe them, exist because we are here to observe them. If life existed and died out before we arrived, it would not have been sophisticated enough to know that it existed, much less observe conditions in the universe that led to its existence. And that would mean the anthropic principle might just be an idea that exists because we have nothing better to explain how and why we are here.

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Quantum "Rainbow" Universe Where Time May Have No Beginning and the Big Bang Never Happened

Quantum "Rainbow" Universe Where Time May Have No Beginning and the Big Bang Never Happened | Amazing Science |

What if the universe had no beginning, and time stretched back infinitely without a big bang to start things off? That's one possible consequence of an idea called "rainbow gravity," so-named because it posits that gravity's effects on spacetime are felt differently by different wavelengths of light, aka different colors in the rainbow.


Rainbow gravity was first proposed 10 years ago as a possible step toward repairing the rifts between the theories of general relativity (covering the very big) and quantum mechanics (concerning the realm of the very small). The idea is not a complete theory for describing quantum effects on gravity, and is not widely accepted. Nevertheless, physicists have now applied the concept to the question of how the universe began, and found that if rainbow gravity is correct, spacetime may have a drastically different origin story than the widely accepted picture of the big bang.


According to Einstein's general relativity, massive objects warp spacetime so that anything traveling through it, including light, takes a curving path. Standard physics says this path shouldn't depend on the energy of the particles moving through spacetime, but in rainbow gravity, it does. "Particles with different energies will actually see different spacetimes, different gravitational fields," says Adel Awad of the Center for Theoretical Physics at Zewail City of Science and Technology in Egypt, who led the new research, published in October in the Journal of Cosmology and Astroparticle Physics. The color of light is determined by its frequency, and because different frequencies correspond to different energies, light particles (photons) of different colors would travel on slightly different paths though spacetime, according to their energy.


The effects would usually be tiny, so that we wouldn't notice the difference in most observations of stars, galaxies and other cosmic phenomena. But with extreme energies, in the case of particles emitted by stellar explosions called gamma-ray bursts, for instance, the change might be detectable. In such situations photons of different wavelengths released by the same gamma-ray burst would reach Earth at slightly different times, after traveling somewhat altered courses through billions of light-years of time and space. "So far we have no conclusive evidence that this is going on," says Giovanni Amelino-Camelia, a physicist at the Sapienza University of Rome who has researched the possibility of such signals. Modern observatories, however, are just now gaining the sensitivity needed to measure these effects, and should improve in coming years.

Vloasis's curator insight, December 9, 2013 2:23 PM

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How close are we to finding dark matter?

How close are we to finding dark matter? | Amazing Science |

Dark matter makes up about a quarter of the cosmos, but we still don't know what it is. As part of a two-part series called Light & Dark on BBC Four, physicist Jim Al-Khalili pondered how close we are to understanding the mysterious "dark stuff".


Given all the progress we've made in modern physics over the past century, you may be forgiven for thinking that physicists are approaching a complete understanding of what makes up everything in our Universe.


For example, all the publicity surrounding the discovery of the Higgs boson last year seemed to be suggesting that this was one of the final pieces of the jigsaw - that all the fundamental building blocks of reality were now known.


So it might come as something of a shock to many people to hear that we still don't know what 95% of the Universe is made of. The stars in galaxies revolve around like undissolved coffee granules on the surface of you mug of coffee just after you've stopped stirring it.

It's all rather embarrassing. Everything we see: our planet and everything on it, the moon, the other planets and their moons, the Sun, all the stars in the sky that make up our Milky Way galaxy, all the other billions of galaxies beyond with their stars and clouds of interstellar gas, as well as all the dead stars and black holes that we can no longer see; it all amounts to less than 5% of the Universe.


And we don't even know if space goes on for ever, what shape the Universe is, what caused the Big Bang that created it, even whether it is just one of many embedded multiverses.

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​What will NASA be doing with its new quantum computer?

​What will NASA be doing with its new quantum computer? | Amazing Science |
Earlier this year, NASA, in partnership with Google, acquired the world's largest quantum computer. But just what does the space agency plan to do with a device with such revolutionary potential?


NASA is currently looking at three very basic applications, including one that would serve as a day-planner for busy astronauts who are up in orbit.


"If you're trying to schedule or plan a whole bunch of tasks on the International Space Station, you can do certain tasks only if certain preconditions are met," he explains. "And after you perform the task you end up in another state where you may or may not be able to perform another task. So that's considered a hard optimization problem that a quantum system could potentially solve."


They're also looking to schedule jobs on supercomputers. And in fact, NASA Ames is responsible for running the agency's primary supercomputing facility. No doubt, at any instance of time they've got hundreds of individual jobs running on a supercomputer, while many others are waiting for their turn. A very difficult scenario would involve a job waiting to run — one that requires, say, 500 nodes — on a supercomputer with 1,000 nodes available.


"Which 500 of these 1,000 nodes should we pick to run the job?," he asks. "It's a very difficult scheduling problem."


Another important application is the Kepler search for exoplanets. NASA astronomers use their various telescopes to look at light curves to understand whether any noticeable dimming represents a potential exoplanet as it moves across its host star. This is a massive search problem — one that D-Wave could conceivably help with.


"These are the types of applications that we're trying to run," says Biswas. "We're doing it on our D-Wave system, which is the largest in the world, but it's still not large enough to solve the really hard real world problems. But by tackling the smaller problems, we can extrapolate to how a larger problem could be solved on a larger system." "But each of these images may be at a certain wavelength, and you may not get all the information from the image," he explains. "One of the challenges there is what's called data fusion, where you try to get multiple images and somehow fuse them in some smart way so that you can garner information from a fused image that you couldn't get from a single image.


And at NASA's Ames Research Center in Silicon Valley, Biswas's team runs the supercomputers that power a significant portion of NASA's endeavors, both public and commercial.


"We see quantum computing as a natural extension of our supercomputing efforts," he told me. "In fact, our current belief is that the D-WAVE system and other quantum computers that might come out in the next few years are all going to behave as attached processors to classical silicon computers."


Which is actually quite amazing. So in the future, when a user wants to solve a large problem, they would interact with their usual computer, while certain aspects would be handed over to the quantum computer. After performing the calculation, like an optimization problem, it would send the solution back to the traditional silicon-based machine. It'll be like putting your desktop PC on steroids.


"Just so we're clear, the D-Wave system is just one of many ways to leverage the effects of quantum physics," he told me. "But in order to use any quantum system, the first thing you need to have is a problem mapped in QUBO form." A QUBO form, which stands for a Quadratic Unconstrained Binary Optimization form, is a mathematical representation of any optimization problem that needs to be solved. At this time — and as far as we know — every single quantum computer requires that the input be in QUBO form.


"And that's a serious problem," says Biswas, "because there's no known recipe to devise a problem and then map it into QUBO form. But once we get a QUBO form — which is a graph representation of the problem — we can embed this onto the architecture of the D-Wave machine."


The D-Wave processors run 512 qubits which are made up of 64 unit cells. Each unit cell is made up of 8 qubits. And each qubit is made up of a bipartite graph, so there are four quibits on the left and four on the right. Each of the four qubits are connected to the ones on the right and vice-versa. But it's not a fully connected graph.


"So what happens therefore, is after you take your problem in QUBO form and you try to embed it into the D-WAVE machine it's not a universal quantum computer. It's not like you have computer keyboard and you can just tell the machine what to do." Essentially, the machine becomes dedicated to the task outlined by the QUBO form — a limitation that could impact scalability.



Scott Gipson's curator insight, December 2, 2013 1:04 AM

       NASA partnered with Google earlier this year to acquire the world’s largest quantum computer. Quantum computers are different from digital computers based on transistors. While digital computers require data to be encoded into binary digits (bits), quantum computation uses quantum properties to represent data and perform operations based on these data. This article discusses the revolutionary potential of the device.

       Quantum systems have the ability to irrevocably change the way we go about computation. Unlike traditional silicon-based computers, these systems tap into the eerie effects of quantum mechanics (namely superposition, entanglement, and parallelism), enabling them to mull over all possible solutions to a problem in a single instant. According to physicist David Deutsch, a quantum system can work on a million computations at once while a standard desktop PC works on just one. These computers will help us find the most convenient solution to a complex problem. As such, they're poised to revolutionize the way we go about data analysis and optimization which include such realms as air traffic control, courier routing, weather prediction, database querying, and hacking tough encryption schemes.

        "Quantum computing has generated a lot of interest recently, particularly the ways in which the D-Wave quantum computer can be used to solve interesting problems. We've had the machine operational since September, and we felt the time is right to give the public a little bit of background on what we've been doing,” said Dr. Rupak Biswas, deputy director of the Exploration Technology Directorate at NASA's Ames Research Center in Silicon Valley.

        Biswas's team is currently looking at three very basic applications, including one that would serve as a day-planner for busy astronauts who are up in orbit. "If you're trying to schedule or plan a whole bunch of tasks on the International Space Station, you can do certain tasks only if certain preconditions are met," he explains. "And after you perform the task you end up in another state where you may or may not be able to perform another task. So that's considered a hard optimization problem that a quantum system could potentially solve."

        NASA is also heavily involved in developing the next generation of air traffic control systems. These involve not only commercial flights, but also cargo and unmanned flights. Currently, much of this is done in a consolidated fashion by air traffic control. But at later stages, when more distributed control is required and highly complex variables like weather need to be taken into account, quantum computing could certainly help.

       This article ties into Chapter 9: Business-to-Business Relations in our Case Studies textbook. “Tactics in business-to-business relations and partner relationship management help companies build productive relationships with other companies” (Guth & Marsh pg. 194). Considering what I’ve read in this article, so far the relationship between the two companies seems to be pretty productive. 

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Gravitational waves help us understand how black-holes gain weight

Gravitational waves help us understand how black-holes gain weight | Amazing Science |
Supermassive black holes: every large galaxy's got one. But here's a real conundrum: how did they grow so big?


A paper in today's issue of Science pits the front-running ideas about the growth of supermassive black holes against observational data -- a limit on the strength of gravitational waves, obtained with CSIRO's Parkes radio telescope in eastern Australia.


"This is the first time we've been able to use information about gravitational waves to study another aspect of the Universe -- the growth of massive black holes," co-author Dr Ramesh Bhat from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) said.


"Black holes are almost impossible to observe directly, but armed with this powerful new tool we're in for some exciting times in astronomy. One model for how black holes grow has already been discounted, and now we're going to start looking at the others."


The study was jointly led by Dr Ryan Shannon, a Postdoctoral Fellow with CSIRO, and Mr Vikram Ravi, a PhD student co-supervised by the University of Melbourne and CSIRO.


Einstein predicted gravitational waves -- ripples in space-time, generated by massive bodies changing speed or direction, bodies like pairs of black holes orbiting each other.


When galaxies merge, their central black holes are doomed to meet. They first waltz together then enter a desperate embrace and merge. "When the black holes get close to meeting they emit gravitational waves at just the frequency that we should be able to detect," Dr Bhat said.


Played out again and again across the Universe, such encounters create a background of gravitational waves, like the noise from a restless crowd.


Astronomers have been searching for gravitational waves with the Parkes radio telescope and a set of 20 small, spinning stars called pulsars. Pulsars act as extremely precise clocks in space. The arrival time of their pulses on Earth are measured with exquisite precision, to within a tenth of a microsecond. When the waves roll through an area of space-time, they temporarily swell or shrink the distances between objects in that region, altering the arrival time of the pulses on Earth.


The Parkes Pulsar Timing Array (PPTA), and an earlier collaboration between CSIRO and Swinburne University, together provide nearly 20 years worth of timing data. This isn't long enough to detect gravitational waves outright, but the team say they're now in the right ballpark.


"The PPTA results are showing us how low the background rate of gravitational waves is," said Dr Bhat.



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Physics: What We Do and Don’t Know. By Steven Weinberg

Physics: What We Do and Don’t Know. By Steven Weinberg | Amazing Science |

In the past fifty years two large branches of physical science have each made a historic transition. I recall both cosmology and elementary particle physics in the early 1960s as cacophonies of competing conjectures. By now in each case we have a widely accepted theory, known as a “standard model.”


Cosmology and elementary particle physics span a range from the largest to the smallest distances about which we have any reliable knowledge. The cosmologist looks out to a cosmic horizon, the farthest distance light could have traveled since the universe became transparent to light over ten billion years ago, while the elementary particle physicist explores distances much smaller than an atomic nucleus. Yet our standard models really work—they allow us to make numerical predictions of high precision, which turn out to agree with observation.

Up to a point the stories of cosmology and particle physics can be told separately. In the end, though, they will come together.

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It's bigger on the inside: Tardis regions in spacetime and the expanding universe

It's bigger on the inside: Tardis regions in spacetime and the expanding universe | Amazing Science |

Fans of Doctor Who will be very familiar with the stupefied phrase uttered by all new visitors to his Tardis: "It's...bigger...on the inside." As it turns out, this apparently irrational idea may have something to contribute to our understanding of the universe. A team of cosmologists in Finland and Poland propose that the observed acceleration of the expansion of the universe, usually explained by dark energy or modified laws of gravity, may actually be the result of regions of spacetime that are larger on the inside than they appear from the outside. The researchers have dubbed these "Tardis regions."


Perhaps the most surprising cosmological observation of the past few decades was the 1998 discovery by Perlmutter, Schmidt and Riess, that the expansion of the universe has been accelerating for the past five billion years. This result, which won the 2011 Nobel Prize, was quickly corroborated by observation of independent phenomena such as the cosmic background radiation.


Why the acceleration is occurring is not currently understood, although it can be described. In terms of conventional cosmological theory, it calls for the existence of a "dark energy," an energy field permeating the universe. However, because gravity attracts normal mass-energy, dark energy would have to have a negative energy density, something unknown as yet in nature. In addition, roughly 75 percent of the contents of the universe have to be made up of dark energy to get the observed acceleration of expansion. Even though dark energy provides a reasonable description of the universal acceleration, its value as an explanation is still controversial. Many have the gut reaction that dark energy is too strange to be true.


Professors Rasanen, and Szybkab, of the University of Helsinki and the Jagellonian University at Krakow, together with Rasanen's graduate student Mikko Lavinto, decided to investigate another possibility.


The "standard cosmological model," which is the framework within which accelerated expansion requires dark energy, was developed in the 1920s and 1930s. The FLRW metric (named for Friedmann, Lemaître, Robertson and Walker, the major contributors) is an exact solution to Einstein's equations. It describes a strictly homogeneous, isotropic universe that can be expanding or contracting.


Strict homogeneity and strict isotropy means that the universe described by an FLRW metric looks the same at a given time from every point in space, at whatever distance or orientation you look. This is a universe in which galaxies, clusters of galaxies, sheets, walls, filaments, and voids do not exist. Not, then, very much like our own Universe, which appears to be rather homogeneous and isotropic when you look at distances greater than about a gigaparsec, but closer in it is nothing of the sort.


Rasanen's research team decided to examine a model universe having a structure closer to ours, in an attempt to look for alternate explanations of the accelerating expansion we see. They took an FLRW metric filled with a uniform density of dust, and converted it into a Swiss cheese model but cutting random holes in it. This has the effect of making the model inhomogeneous and non-isotropic (except very far away), and hence the Swiss cheese model looks more like our own Universe, save for the fact that our Universe does not seem to be full of holes.


While Swiss cheese is delicious, a universe with holes is not. To rectify this, Rasanen's team filled in the holes with plugs made from dust-filled exact solutions of Einstein's equation. These plugs are a reasonable model of the region near a sizable body, such as a galaxy. By putting the plugs in the holes, and then smoothing the intersections between them, they obtained a rather uniform spacetime with a lot of smaller blobs of matter dispersed throughout it – a (very) simple analog to the structure of the universe in which we live.

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NASA'S Swift reveals new phenomenon in a neutron star

NASA'S Swift reveals new phenomenon in a neutron star | Amazing Science |

Astronomers using NASA's Swift X-ray Telescope have observed a spinning neutron star suddenly slowing down, yielding clues they can use to understand these extremely dense objects.

A neutron star is the crushed core of a massive star that ran out of fuel, collapsed under its own weight, and exploded as a supernova.

A neutron star can spin as fast as 43,000 times per minute and boast a magnetic field a trillion times stronger than earth's. Matter within a neutron star is so dense a teaspoonful would weigh about a billion tons on earth.

This neutron star, 1E 2259+586, is located about 10,000 light-years away toward the constellation Cassiopeia. It is one of about two dozen neutron stars called magnetars, which have very powerful magnetic fields and occasionally produce high-energy explosions or pulses.

Observations of X-ray pulses from 1E 2259+586 from July 2011 through mid-Apr 2012 indicated the magnetar's rotation was gradually slowing from once every seven seconds, or about eight revolutions per minute.

On Apr 28, 2012, data showed the spin rate had decreased abruptly, by 2.2 millionths of a second, and the magnetar was spinning down at a faster rate.

"Astronomers have witnessed hundreds of events, called glitches, associated with sudden increases in the spin of neutron stars, but this sudden spin-down caught us off guard," said Victoria Kaspi, a professor of physics at McGill University in Montreal. She leads a team that uses Swift to monitor magnetars routinely.

Astronomers dubbed the event an "anti-glitch," said co-author Neil Gehrels, principal investigator of the Swift mission at NASA's Goddard Space Flight Center in Greenbelt, Md. "It affected the magnetar in exactly the opposite manner of every other clearly identified glitch seen in neutron stars."

The discovery has important implications for understanding the extreme physical conditions present within neutron stars, where matter becomes squeezed to densities several times greater than an atomic nucleus. No laboratory on Earth can duplicate these conditions.

The internal structure of neutron stars is a long-standing puzzle.

Current theory maintains a neutron star has a crust made up of electrons and ions; an interior containing oddities that include a neutron superfluid, which is a bizarre state of matter without friction; and a surface that accelerates streams of high-energy particles through the star's intense magnetic field.

The streaming particles drain energy from the crust.

The crust spins down, but the fluid interior resists being slowed. The crust fractures under the strain. When this happens, a glitch occurs.

There is an X-ray outburst and the star gets a speedup kick from the faster-spinning interior.

Processes that lead to a sudden rotational slowdown constitute a new theoretical challenge.

On Apr 21, 2012, just a week before Swift observed the anti-glitch, 1E 2259+586 produced a brief, but intense X-ray burst detected by the Gamma-ray Burst Monitor aboard NASA's Fermi Gamma-ray Space Telescope.

The scientists think this 36-millisecond eruption of high-energy light likely signaled the changes that drove the magnetar's slowdown.

"What is really remarkable about this event is the combination of the magnetar's abrupt slowdown, the X-ray outburst, and the fact we now observe the star spinning down at a faster rate than before," said lead author Robert Archibald, a graduate student at McGill.

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