Posts Tagged ‘Physics’

Posted: December 26, 2012 by Wildcat in Uncategorized
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The doctrine that the world is made up of objects whose existence is independent of human consciousness turns out to be in conflict with quantum mechanics and with facts established by experiment.”[1]

Bernard d’Espagnat

Bernard d’Espagnat (born 1921) is a French theoretical physicist, philosopher of science, and author, best known for his work on the nature of reality.

Posted: December 26, 2012 by Wildcat in Uncategorized
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You’ve heard the hype a hundred times: Physicists hope to someday build a whiz-bang quantum computer that can solve problems that would overwhelm an ordinary computer. Now, four separate teams have taken a step toward achieving such “quantum speed-up” by demonstrating a simpler, more limited form of quantum computing that, if it can be improved, might soon give classical computers a run for their money. But don’t get your hopes up for a full-fledged quantum computer. The gizmos may not be good for much beyond one particular calculation. Even with the caveats, the challenge of quantum computing has proven so difficult that the new papers are gaining notice. “The question is, does this give you a first step to doing a hard calculation quantum mechanically, and it looks like it might,” says Scott Aaronson, a theoretical computer scientist at the Massachusetts Institute of Technology (MIT) in Cambridge and an author on one of the papers. (via New Form of Quantum Computation Promises Showdown With Ordinary Computers – ScienceNOW)

The 500 phases of matter: Entering a new phase

Posted: December 22, 2012 by Wildcat in Uncategorized
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Forget solid, liquid, and gas: there are in fact more than 500 phases of matter. In a major paper in today’s issue of Science, Perimeter Faculty member Xiao-Gang Wen reveals a modern reclassification of all of them. Using modern mathematics, Wen and collaborators reveal a new system which can, at last, successfully classify symmetry-protected phases of matter. Their new classification system will provide insight about these quantum phases of matter, which may in turn increase our ability to design states of matter for use in superconductors or quantum computers. This paper, titled, “Symmetry-Protected Topological Orders in Interacting Bosonic Systems,” is a revealing look at the intricate and fascinating world of quantum entanglement, and an important step toward a modern reclassification of all phases of matter.

The 500 phases of matter: Entering a new phase

Has the cosmos existed forever, or did something bring it into existence? Time to grapple with the universe’s greatest mystery AS BIG questions go, it’s hard to beat. Has the universe existed forever? Over the years, some of the greatest minds in physics have argued that no matter how far back in time you go, the universe has always been here. Others have argued that the opposite must be true – something must have happened to bring the cosmos into existence. With both sides claiming that observations support their view, until recently an answer seemed as distant as ever. However, earlier this year, cosmologists Alex Vilenkin and Audrey Mithani claimed to have settled the debate. They have uncovered reasons why the universe cannot have existed forever. Yet what nature grudgingly gives with one hand, it takes back with the other – even though the universe has a beginning, its origins may be lost in the mists of time. Modern cosmology began in 1916 when Einstein applied his newly formulated theory of gravity, general relativity, to the biggest gravitating mass he could think of: the entire universe. Like Newton, Einstein favoured an unchanging universe – a universe that had existed forever and therefore had no beginning. To achieve this, Einstein realised that the gravity pulling together all the matter in the universe had to be countered by a weird cosmic repulsion of empty space. Einstein’s static universe was unfortunately unstable. As the English physicist Arthur Eddington pointed out, such a universe was balanced on a knife-edge between runaway expansion and runaway contraction. A further blow came in 1929 when American astronomer Edwin Hubble observed that galaxies were flying apart from each other like pieces of cosmic shrapnel. The conclusion was that the universe was expanding. Yet if the universe was expanding, an unavoidable consequence must be that it had been smaller in the past. Imagine rewinding that expansion back to a time when everything was compressed into the tiniest of volumes. This was the big bang.

Before the big bang: something or nothing – space – 03 December 2012 – New Scientist

Say goodbye to that annoying buzz created by overhead fluorescent light bulbs in your office. Scientists at Wake Forest University have developed a flicker-free, shatterproof alternative for large-scale lighting. The lighting, based on field-induced polymer electroluminescent (FIPEL) technology, also gives off soft, white light – not the yellowish glint from fluorescents or bluish tinge from LEDs. “People often complain that fluorescent lights bother their eyes, and the hum from the fluorescent tubes irritates anyone sitting at a desk underneath them,” said David Carroll, the scientist leading the development of this technology at Wake Forest. “The new lights we have created can cure both of those problems and more.” The team uses a nano-engineered polymer matrix to convert the charge into light. This allows the researchers to create an entirely new light bulb – overcoming one of the major barriers in using plastic lights in commercial buildings and homes. The research supporting the technology is described in a study appearing online in advance of publication in the peer-reviewed journal Organic Electronics.

Goodbye, fluorescent light bulbs: New lighting technology won’t flicker, shatter or burn out

Posted: December 2, 2012 by Wildcat in Uncategorized
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Can we find evidence for quantum gravity? That’s a major puzzle in Physics. This might be possible using a simple table-top experiment, according to Jacob Bekenstein, at the Hebrew University of Jerusalem. Why should we take him seriously? Bekenstein is best known for studying the thermal properties of black holes, showing that entropy is proportional to the surface area of a black hole’s event horizon, recently announced an amazing proposal to use single photons for probing what is known as “quantum foam.” The quantum foam idea was introduced in 1955 by the American physicist John Archibald Wheeler, and is believed to exist on length scales so small that quantum fluctuations affect the very structure or texture of space–time. Bekenstein’s proposal is one of the the latest assaults in the quest to understand how quantum mechanics might be unified with Einstein’s General Theory of Relativity. Such a Unified Field Theory has escaped the grasp of physicists since they first began to understand the quantum and relativistic worlds in the early 20th century.
Why? A major challenge in coming up with a workable theory of quantum gravity is a complete lack of experimental evidence. The effects of quantum gravity are only expected to be measurable over extremely small distances. VERY VERY extremely small distances. But Bekenstein may have invented a clever loophole.

Quantum Foam – Can We detect Planck-length Weirdness with a Table-top Experiment?

(Phys.org)—A new paradigm for understanding the earliest eras in the history of the universe has been developed by scientists at Penn State University. Using techniques from an area of modern physics called loop quantum cosmology, developed at Penn State, the scientists now have extended analyses that include quantum physics farther back in time than ever before—all the way to the beginning. The new paradigm of loop quantum origins shows, for the first time, that the large-scale structures we now see in the universe evolved from fundamental fluctuations in the essential quantum nature of “space-time,” which existed even at the very beginning of the universe over 14 billion years ago. The achievement also provides new opportunities for testing competing theories of modern cosmology against breakthrough observations expected from next-generation telescopes. The research will be published on 11 December 2012 as an “Editor’s Suggestion” paper in the scientific journal Physical Review Letters. “We humans always have yearned to understand more about the origin and evolution of our universe,” said Abhay Ashtekar, the senior author of the paper. “So it is an exciting time in our group right now, as we begin using our new paradigm to understand, in more detail, the dynamics that matter and geometry experienced during the earliest eras of the universe, including at the very beginning.” Ashtekar is the Holder of the Eberly Family Chair in Physics at Penn State and the director of the university’s Institute for Gravitation and the Cosmos. Coauthors of the paper, along with Ashtekar, are postdoctoral fellows Ivan Agullo and William Nelson.

The beginning of everything: A new paradigm shift for the infant universe