tag:blogger.com,1999:blog-5719491025572183142024-02-18T19:28:39.447-08:00PhysicswhynotΔρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.comBlogger74125tag:blogger.com,1999:blog-571949102557218314.post-82179165236188759702014-03-17T10:33:00.000-07:002014-03-17T10:33:06.755-07:00'Huge' Physics Finding Supports Big Bang Theory<div class="separator" style="clear: both; text-align: center;">
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<br />Scientists announced today (March 17) that they had found the first direct evidence of the dramatic expansion that created the known universe, known as cosmic inflation, or the "bang" in<a href="http://www.popsci.com/science/article/2013-06/scientists-solve-inconsistency-big-bang-theory">the Big Bang</a>. This dramatic expansion is thought to have occurred in the first instants of existence, nearly 14 billion years ago, causing the universe to expand beyond the reach of the most powerful telescopes. <a name='more'></a><br />In 1979, a physicist named Alan Guth came up with the theory of cosmic inflation, and theorized that such an event would create ripples in space-time called gravitational waves. But their existence remained hypothetical. Today, a team of researchers said that they had detected these gravitational waves, using a telescope near the South Pole. <br /><br />"This is huge," Marc Kamionkowski, a researcher at Johns Hopkins University who was not involved in the discovery but who predicted how these gravitational wave imprints could be found,<a href="http://www.scientificamerican.com/article/gravity-waves-cmb-b-mode-polarization/">told Scientific American</a>. “It’s not every day that you wake up and find out something completely new about the early universe." He added that the results looked good, although they would need to be verified by others to hold up. <br /><br />The finding seems to support the idea that the observable universe is only one of many, as <a href="http://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html?_r=1">the New York Times reports</a>: <br /><br />Confirming inflation would mean that the universe we see... is only an infinitesimal patch in a larger cosmos whose extent, architecture and fate are unknowable. Moreover, beyond our own universe there might be an endless number of other universes bubbling into frothy eternity, like a pot of pasta water boiling over.<br /><br />As the Times tells it, Andrei Linde, who first described the most popular variant of inflation, known as chaotic inflation, in 1983, was about to go on vacation in the Caribbean last week when a colleague named Chao-Lin Kuo knocked on his door with a bottle of Champagne to tell him the news. <br /><br /><br />Confused, Dr. Linde called out to his wife, asking if she had ordered Champagne.<br /><br />"And then I told him that in the beginning we thought that this was a delivery but we did not think that we ordered anything, but I simply forgot that actually I did order it, 30 years ago," Dr. Linde wrote in an email.<div>
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http://www.popsci.com/</div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com2tag:blogger.com,1999:blog-571949102557218314.post-25970966819087379872014-02-25T08:42:00.000-08:002014-02-25T08:42:03.508-08:00Einstein’s lost theory uncovered<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small; text-align: start;">Albert Einstein at Mount Wilson Observatory in 1931, with Edwin Hubble (centre) and Walter Adams.</span></td></tr>
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<br />A manuscript that lay unnoticed by scientists for decades has revealed that Albert Einstein once dabbled with an alternative to what we now know as the Big Bang theory, proposing instead that the Universe expanded steadily and eternally. The recently uncovered work, written in 1931, is reminiscent of a theory championed by British astrophysicist Fred Hoyle nearly 20 years later. Einstein soon abandoned the idea, but the manuscript reveals his continued hesitance to accept that the Universe was created during a single explosive event.<a name='more'></a>Evidence for the Big Bang first emerged in the 1920s, when US astronomer Edwin Hubble and others discovered that distant galaxies are moving away and that space itself is expanding. This seemed to imply that, in the past, the contents of the observable Universe had been a very dense and hot ‘primordial broth’.<br />But, from the late 1940s, Hoyle argued that space could be expanding eternally and keeping a roughly constant density. It could do this by continually adding new matter, with elementary particles spontaneously popping up from space, Hoyle said. Particles would then coalesce to form galaxies and stars, and these would appear at just the right rate to take up the extra room created by the expansion of space. Hoyle’s Universe was always infinite, so its size did not change as it expanded. It was in a ‘steady state’.<br /><br />The newly uncovered document shows that Einstein had described essentially the same idea much earlier. “For the density to remain constant new particles of matter must be continually formed,” he writes. The manuscript is thought to have been produced during a trip to California in 1931 — in part because it was written on American note paper.<br /><br />It had been stored in plain sight at the Albert Einstein Archives in Jerusalem — and is <a href="http://alberteinstein.info/vufind1/Record/EAR000034354">freely available to view on its website</a> — but had been mistakenly classified as a first draft of another Einstein paper. Cormac O’Raifeartaigh, a physicist at the Waterford Institute of Technology in Ireland, says that he “almost fell out of his chair” when he realized what the manuscript was about. He and his collaborators have posted their findings, together with an English translation of Einstein’s original German manuscript, on the arXiv preprint server (C. O’Raifeartaigh et al. Preprint at<a href="http://arxiv.org/abs/1402.0132">http://arxiv.org/abs/1402.0132</a>; 2014) and have submitted their paper to the European Physical Journal.<br /><br />“This finding confirms that Hoyle was not a crank,” says study co-author Simon Mitton, a science historian at the University of Cambridge, UK, who wrote the 2005 biography Fred Hoyle: A Life in Science. The mere fact that Einstein had toyed with a steady-state model could have lent Hoyle more credibility as he engaged the physics community in a debate on the subject. “If only Hoyle had known, he would certainly have used it to punch his opponents,” O’Raifeartaigh says.<br /><img src="http://www.nature.com/polopoly_fs/7.15719.1393266606!/image/Einstein%20ms%20page%20crop2%20%202-112_3.jpg_gen/derivatives/landscape_630/Einstein%20ms%20page%20crop2%20%202-112_3.jpg" /><br /><br />Albert Einstein Archives, Hebrew University of Jerusalem, Israel<br /><br />Einstein’s correction to his erroneous calculation.<br /><br />Although Hoyle’s model was eventually ruled out by astronomical observations, it was at least mathematically consistent, tweaking the equations of Einstein’s general theory of relativity to provide a possible mechanism for the spontaneous generation of matter. Einstein’s unpublished manuscript suggests that, at first, he believed that such a mechanism could arise from his original theory without modification. But then he realized that he had made a mistake in his calculations, O’Raifeartaigh and his team suggest. When he corrected it — crossing out a number with a pen of a different colour — he probably decided that the idea would not work and set it aside.<br /><br />The manuscript was probably “a rough draft commenced with excitement over a neat idea and soon abandoned as the author realized he was fooling himself”, says cosmologist James Peebles of Princeton University in New Jersey. There seems to be no record of Einstein ever mentioning these calculations again.<br /><br />But the fact that Einstein experimented with the steady-state concept demonstrates his continued resistance to the idea of a Big Bang, which he at first found “abominable”, even though other theoreticians had shown it to be a natural consequence of his general theory of relativity. (Other leading researchers, such as the eminent Cambridge astronomer Arthur Eddington, were also suspicious of the Big Bang idea, because it suggested a mystical moment of creation.) When astronomers found evidence for cosmic expansion, Einstein had to abandon his bias towards a static Universe, and a steady-state Universe was the next best thing, O’Raifeartaigh and his collaborators say.<br /><br />Helge Kragh, a science historian at Aarhus University in Denmark, agrees. “What the manuscript shows is that although by then he accepted the expansion of space, [Einstein] was unhappy with a Universe changing in time,” he says.<div>
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Nature 506, 418–419 (27 February 2014) doi:10.1038/506418a</div>
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<a href="http://www.nature.com/news/einstein-s-lost-theory-uncovered-1.14767">http://www.nature.com/news/einstein-s-lost-theory-uncovered-1.14767</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-53244633131998345252014-02-18T09:47:00.001-08:002014-02-18T09:47:56.244-08:00Early night cost Higgs credit for big physics theory<div class="separator" style="clear: both; text-align: center;">
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<br />Nobel laureate Peter Higgs could have been one of the architects of physics' biggest theory - but missed out because of an early night.<a name='more'></a><br />He says he was at a science meeting in 1960 where physicists contemplated ideas that would lead to a "theory of everything" - the Standard Model.<br />But the discussion went on into the small hours, and Prof Higgs went to bed early.<br />He thus failed to make a key connection between his work and that of others.<br />Three years after the British physicist predicted the existence of the Higgs mechanism, it was shown to be central to the Standard Model, the dominant "big theory" in physics, and our best understanding of how the Universe works.<br />The suggestion is contained in a revealing interview with Prof Higgs on BBC Radio 4's The Life Scientific.<br />In the interview, he also blames his work for the breakdown of his marriage.<br />The Higgs mechanism explains why particles have mass. It predicts the existence of a particle, the Higgs boson, which was finally detected at Cern in 2012, after a 50-year effort.<br />Last year, Prof Higgs and Belgian physicist François Englert were awarded the Nobel Prize in Physics for their work on the idea.<br />But Prof Higgs told the programme that he missed its true significance at the time. The physicists Shelley Glashow, Abdus Salam and Steven Weinberg received a Nobel prize in 1979 for ideas that lie at the heart of the Standard Model, and Prof Higgs might have been among them.<div>
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<a href="http://www.bbc.co.uk/news/science-environment-26014584">http://www.bbc.co.uk/news/science-environment-26014584</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com1tag:blogger.com,1999:blog-571949102557218314.post-20727703300290066692014-02-17T11:33:00.000-08:002014-02-17T11:33:17.145-08:00Stephen Hawking: Syria's war must end<div class="separator" style="clear: both; text-align: center;">
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<span class="detail-spot" style="font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 21px;"><strong>The Greek philosopher Aristotle believed that the universe had existed forever. The reason humanity was not more developed, he believed, was that floods or other natural disasters repeatedly set civilization back to the beginning.<a name='more'></a></strong></span></div>
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Today, humans are developing ever faster. Our knowledge is growing exponentially and with it, our technology. But humans still have the instincts, and in particular the aggressive impulses, that we had in caveman days. Aggression has had definite advantages for survival, but when modern technology meets ancient aggression the entire human race and much of the rest of life on Earth is at risk.</div>
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Today in Syria we see modern technology in the form of bombs, chemicals and other weapons being used to further so-called intelligent political ends.</div>
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But it does not feel intelligent to watch as more than 100,000 people are killed or while children are targeted. It feels downright stupid, and worse, to prevent humanitarian supplies from reaching clinics where, as Save the Children will document in a forthcoming report, children are having limbs amputated for lack of basic facilities and newborn babies are dying in incubators for lack of power.</div>
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What's happening in Syria is an abomination, one that the world is watching coldly from a distance. Where is our emotional intelligence, our sense of collective justice?</div>
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When I discuss intelligent life in the universe, I take this to include the human race, even though much of its behavior throughout history appears not to have been calculated to aid the survival of the species. And while it is not clear that, unlike aggression, intelligence has any long-term survival value, our very human brand of intelligence denotes an ability to reason and plan for not only our own but also our collective futures.</div>
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We must work together to end this war and to protect the children of Syria. The international community has watched from the sidelines for three years as this conflict rages, engulfing all hope. As a father and grandfather, I watch the suffering of Syria's children and must now say: No more.</div>
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I often wonder what we must look like to other beings watching from deep space. As we look out at the universe, we are looking back in time, because light leaving distant objects reaches us much, much later. What does the light emitting from Earth today show? When people see our past, will we be proud of what they are shown — how we, as brothers, treat each other? How we allow our brothers to treat our children?</div>
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We now know that Aristotle was wrong: The universe has not existed forever. It began about 14 billion years ago. But he was right that great disasters represent major steps backward for civilization. The war in Syria may not represent the end of humanity, but every injustice committed is a chip in the facade of what holds us together. The universal principle of justice may not be rooted in physics but it is no less fundamental to our existence. For without it, before long, human beings will surely cease to exist.</div>
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<em>Stephen Hawking is the author of "A Brief History of Time" and a former professor of mathematics at the University of Cambridge.</em></div>
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<span style="font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><span style="line-height: 21px;"><i>http://www.todayszaman.com/</i></span></span></span></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-66760064181342989862013-12-08T23:51:00.001-08:002013-12-08T23:51:03.501-08:00Peter Higgs: I wouldn't be productive enough for today's academic system<div class="separator" style="clear: both; text-align: center;">
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<br /><a href="http://www.theguardian.com/science/peterhiggs">Peter Higgs</a>, the British physicist who gave his name to the <a href="http://www.theguardian.com/science/higgs-boson">Higgs boson</a>, believes no university would employ him in today's academic system because he would not be considered "productive" enough.<a name='more'></a><br />The emeritus professor at Edinburgh University, who says he has never sent an email, browsed the internet or even made a mobile phone call, published fewer than 10 papers after his groundbreaking work, which identified the mechanism by which subatomic material acquires mass, was published in 1964.<br />He doubts a similar breakthrough could be achieved in today's academic culture, because of the expectations on academics to collaborate and keep churning out papers. He said: "It's difficult to imagine how I would ever have enough peace and quiet in the present sort of climate to do what I did in 1964."<br />Speaking to the Guardian en route to Stockholm to receive the 2013 Nobel prize for science, Higgs, 84, said he would almost certainly have been sacked had he not been nominated for the Nobel in 1980.<br />Edinburgh University's authorities then took the view, he later learned, that he "might get a Nobel prize – and if he doesn't we can always get rid of him".<br />Higgs said he became "an embarrassment to the department when they did research assessment exercises". A message would go around the department saying: "Please give a list of your recent publications." Higgs said: "I would send back a statement: 'None.' "<br />By the time he retired in 1996, he was uncomfortable with the new academic culture. "After I retired it was quite a long time before I went back to my department. I thought I was well out of it. It wasn't my way of doing things any more. Today I wouldn't get an academic job. It's as simple as that. I don't think I would be regarded as productive enough."<br />Higgs revealed that his career had also been jeopardised by his disagreements in the 1960s and 70s with the then principal, Michael Swann, who went on to chair the BBC. Higgs objected to Swann's handling of student protests and to the university's shareholdings in South African companies during the apartheid regime. "[Swann] didn't understand the issues, and denounced the student leaders."<br />He regrets that the particle he identified in 1964 became known as the "God particle".<br />He said: "Some people get confused between the science and the theology. They claim that what happened at <a href="http://www.theguardian.com/science/cern">Cern</a> proves the existence of God."<br />An atheist since the age of 10, he fears the nickname "reinforces confused thinking in the heads of people who are already thinking in a confused way. If they believe that story about creation in seven days, are they being intelligent?"<br />He also revealed that he turned down a knighthood in 1999. "I'm rather cynical about the way the honours system is used, frankly. A whole lot of the honours system is used for political purposes by the government in power."<br />He has not yet decided which way he will vote in the referendum on<a href="http://www.theguardian.com/politics/scottish-independence">Scottish independence</a>. "My attitude would depend a little bit on how much progress the lunatic right of the Conservative party makes in trying to get us out of <a href="http://www.theguardian.com/world/europe-news">Europe</a>. If the UK were threatening to withdraw from Europe, I would certainly want <a href="http://www.theguardian.com/uk/scotland">Scotland</a> to be out of that."<br />He has never been tempted to buy a television, but was persuaded to watch The Big Bang Theory last year, and said he wasn't impressed.<div>
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<a href="http://www.theguardian.com/science/2013/dec/06/peter-higgs-boson-academic-system">http://www.theguardian.com/science/2013/dec/06/peter-higgs-boson-academic-system</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-45185025403963486252013-11-17T09:39:00.000-08:002013-11-17T09:39:36.677-08:00The tao of modern physics<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;"><a href="http://en.wikipedia.org/wiki/Philip_Warren_Anderson" style="font-size: medium; text-align: start;">Philip Warren Anderson</a></td></tr>
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Shivaji Sondhi<div>
<a name='more'></a><br />In the bulk of the commentary on the discovery of the Higgs particle at CERN and the recent award of the Nobel prize to Peter Higgs and François Englert, one astonishing aspect has been largely overlooked. This discovery points to one of the most central aspects of postwar physics — its unity across domains at distances (or energies) separated by vast gulfs that have allowed ideas to jump between very different physical problems. In the case of the Higgs particle, its discovery at an energy of one hundred billion electron volts in a complicated special purpose machine is, in a mathematical sense, a precise analogue of a well-understood phenomenon in ordinary metals at an energy of a thousandth of an electron volt — one hundred trillion times lower!<br /><br />Indeed, this analogy is how the puzzle underlying the Higgs particle was first solved by Philip Anderson in 1963, a year before the papers by Higgs and Englert and Robert Brout that were honoured with the Nobel. Anderson, now 89, is widely regarded as the greatest living condensed matter physicist, a maestro of the part of physics that tries to understand how the small set of subatomic forces and particles can lead to the infinite variety of the matter we see around us. He has led a spectacular career during which he picked up a Nobel in 1977 for completely different work, and could have collected at least two more.<br /><br />Back in 1963, Anderson had already played a key role in understanding the general phenomenon of “spontaneous symmetry breaking” in condensed matter physics in parallel with important developments in particle physics. An everyday example of this phenomenon is the formation of ice from water. While the molecules in water resemble the crowd in Times Square on a busy day with no clear preference for where they want to be, the molecules in ice are arranged in an array like an honour guard at attention. Their choice of particular positions breaks the symmetry embodied in a lack of positional preference.<br /><br />More immediately, Anderson had been one of the central players in elucidating the physics of superconductivity, or why metals permit electric current to flow without loss when sufficiently cold. Superconductivity involves an unusual broken symmetry, but with the complication of electromagnetic forces that act over large distances. It was understood by Anderson that a “massless gauge field” (describing ordinary electromagnetic forces) could combine with a “massless Goldstone mode” (a signature of symmetry breaking) to yield purely massive excitations. Roughly, this reflects the dislike that superconductors exhibit for magnetic fields, termed the Meissner effect and often dramatised by levitating magnets above pieces of superconductors.<br /><br />At this point, Anderson came across particle physicists trying to rescue an appealing potential description of short-ranged forces among the zoo of particles being discovered in accelerators. This description had one key thing wrong — the gauge fields were massless and thus described long-ranged forces. Anderson realised that by introducing a second wrong — a massless Goldstone boson due to symmetry breaking — he could make a right. Today, this magic trick is commonly referred to as the Anderson-Higgs mechanism, to credit Higgs with the subsequent realisation that the mechanism implied a specific additional massive particle Anderson had overlooked. In any event, by staring into a piece of metal, Anderson had divined the solution to a puzzle about fundamental particles.<br /><br />Now, the energy involved in superconductivity is a thousandth of an electron volt while the energy of the Higgs particle is a hundred trillion times larger, or alternately the size of the Higgs particle is a hundred trillion times smaller than the size of the smallest superconducting unit, the so-called “Cooper pair” of electrons. Why is it that the same mathematics can be used to describe both?<br /><br />The explanation for this astonishing fact is a central meta-idea in postwar physics, that of the effective field theory. It states that if you don’t look too closely at the spatial details, the mathematics simplifies greatly into a set of “field theories”, which then provide a unifying mathematical framework for a vast range of phenomena. This meta-idea itself has a precise mathematical formulation known as “universality under renormalisation group flows”.<br /><br />Metals are made of electrons and nuclei, but when we smooth over such detail, we end up with the field theory Anderson considered. In particle physics, the details being smoothed over are unknown — perhaps described by string theory — and we end up with a close cousin of Anderson’s field theory. What Anderson called a mode, Higgs called a particle, but both were describing a disturbance in an underlying medium, one known and the other unknown.<br /><br />The ubiquity of effective field theories means that the Anderson-Higgs mechanism is by no means the only example of tight analogies between far separated phenomena in modern physics. To take one recent example, the work of particle physicist Edward Witten on topological field theories in the 1980s, for which he won a Fields medal in mathematics, has turned out to be central to our understanding of the quantum Hall effect in semiconductor systems, even though it was designed to do no such thing. Even this writer, also a condensed matter physicist, has had the (far more modest) pleasure of discovering in the same semiconductor systems “skyrmions” 15 orders of magnitude larger than those considered by particle physicist Tony Skyrme as descriptions of protons and neutrons.<br /><br />So, the discovery of the Higgs particle is a triumph for this syncretic view built into modern physics. It turns out that space devoid of visible particles has something deeply in common with a superconducting metal. Further, it tells us that it was not always so: when the universe was younger and hotter, it resembled more a piece of superconductor heated to the point where the superconductivity vanishes, and thus there was no Higgs particle to speak of.<br /><br />This brings me to the Nobel prize. I believe the committee missed an opportunity in not including Anderson along with Higgs and Englert. It would have been a more accurate accounting of the credit on this particular discovery and a deserved honour for a man whose contributions are legion. Above all, it would have paid tribute to the remarkable intellectual unity of modern physics.<br /><br />The writer is a professor of physics at Princeton University, US<br /><br /><a href="http://www.indianexpress.com/news/the-tao-of-modern-physics/1195124/0">http://www.indianexpress.com/news/the-tao-of-modern-physics/1195124/0</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-26090503676825658082013-08-03T02:02:00.000-07:002013-08-03T02:04:52.715-07:00When fluid dynamics mimic quantum mechanics<div class="separator" style="clear: both; text-align: center;">
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In the early days of quantum physics, in an attempt to explain the wavelike behavior of quantum particles, the French physicist Louis de Broglie proposed what he called a “pilot wave” theory. According to de Broglie, moving particles—such as electrons, or the photons in a beam of light—are borne along on waves of some type, like driftwood on a tide.<br />
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Physicists’ inability to detect de Broglie’s posited waves led them, for the most part, to abandon pilot-wave theory. Recently, however, a real pilot-wave system has been discovered, in which a drop of fluid bounces across a vibrating fluid bath, propelled by waves produced by its own collisions.<br />
In 2006, Yves Couder and Emmanuel Fort, physicists at Université Paris Diderot, used this system to reproduce one of the most famous experiments in quantum physics: the so-called “double-slit” experiment, in which particles are fired at a screen through a barrier with two holes in it.<br />
In the latest issue of the journal Physical Review E (PRE), a team of MIT researchers, in collaboration with Couder and his colleagues, report that they have produced the fluidic analogue of another classic quantum experiment, in which electrons are confined to a circular “corral” by a ring of ions. In the new experiments, bouncing drops of fluid mimicked the electrons’ statistical behavior with remarkable accuracy.<br />
“This hydrodynamic system is subtle, and extraordinarily rich in terms of mathematical modeling,” says John Bush, a professor of applied mathematics at MIT and corresponding author on the new paper. “It’s the first pilot-wave system discovered and gives insight into how rational quantum dynamics might work, were such a thing to exist.”<br />
Joining Bush on the PRE paper are lead author Daniel Harris, a graduate student in mathematics at MIT; Couder and Fort; and Julien Moukhtar, also of Université Paris Diderot. In a separate pair of papers, appearing this month in the Journal of Fluid Mechanics, Bush and Jan Molacek, another MIT graduate student in mathematics, explain the fluid mechanics that underlie the system’s behavior.<br />
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<b>Interference inference</b></div>
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The double-slit experiment is seminal because it offers the clearest demonstration of wave-particle duality: As the theoretical physicist Richard Feynman once put it, “Any other situation in quantum mechanics, it turns out, can always be explained by saying, ‘You remember the case of the experiment with the two holes? It’s the same thing.’”<br />
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If a wave traveling on the surface of water strikes a barrier with two slits in it, two waves will emerge on the other side. Where the crests of those waves intersect, they form a larger wave; where a crest intersects with a trough, the fluid is still. A bank of pressure sensors struck by the waves would register an “interference pattern”—a series of alternating light and dark bands indicating where the waves reinforced or canceled each other.<br />
Photons fired through a screen with two holes in it produce a similar interference pattern—even when they’re fired one at a time. That’s wave-particle duality: the mathematics of wave mechanics explains the statistical behavior of moving particles.<br />
In the experiments reported in PRE, the researchers mounted a shallow tray with a circular depression in it on a vibrating stand. They filled the tray with a silicone oil and began vibrating it at a rate just below that required to produce surface waves.<br />
They then dropped a single droplet of the same oil into the bath. The droplet bounced up and down, producing waves that pushed it along the surface.<br />
The waves generated by the bouncing droplet reflected off the corral walls, confining the droplet within the circle and interfering with each other to create complicated patterns. As the droplet bounced off the waves, its motion appeared to be entirely random, but over time, it proved to favor certain regions of the bath over others. It was found most frequently near the center of the circle, then, with slowly diminishing frequency, in concentric rings whose distance from each other was determined by the wavelength of the pilot wave.<br />
The statistical description of the droplet’s location is analogous to that of an electron confined to a circular quantum corral and has a similar, wavelike form.<br />
“It’s a great result,” says Paul Milewski, a math professor at the University of Bath, in England, who specializes in fluid mechanics. “Given the number of quantum-mechanical analogues of this mechanical system already shown, it’s not an enormous surprise that the corral experiment also behaves like quantum mechanics. But they’ve done an amazingly careful job, because it takes very accurate measurements over a very long time of this droplet bouncing to get this probability distribution.”<br />
“If you have a system that is deterministic and is what we call in the business ‘chaotic,’ or sensitive to initial conditions, sensitive to perturbations, then it can behave probabilistically,” Milewski continues. “Experiments like this weren’t available to the giants of quantum mechanics. They also didn’t know anything about chaos. Suppose these guys—who were puzzled by why the world behaves in this strange probabilistic way—actually had access to experiments like this and had the knowledge of chaos, would they have come up with an equivalent, deterministic theory of quantum mechanics, which is not the current one? That’s what I find exciting from the quantum perspective.”<br />
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Read more at: <a href="http://phys.org/news/2013-07-fluid-dynamics-mimic-quantum-mechanics.html#jCp">http://phys.org/news/2013-07-fluid-dynamics-mimic-quantum-mechanics.html#jCp</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-78986691573660468382013-04-20T01:24:00.000-07:002013-04-20T01:24:13.606-07:00Austerity-led brain drain is killing Greek science<br />
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Science in Greece is going backwards. This month, researchers lost access to the journal <i>Bioinformatics</i>, a top-ranked title in mathematical and computational biology. Many more publications are likely to disappear from Greek libraries. The Ministry of Education has not paid the bills for its subscription bundles. The largest publishers — including Elsevier, Springer and Taylor & Francis — have threatened to suspend access. Others have done so already.</div>
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The denial of scholarly papers, the lifeblood of research, to Greek scientists could mark the beginning of the end for creative science at universities and research institutes. We will no longer be able to keep up with international contributions. In areas such as biomedicine, it is crucial to have access to the latest information. Many Greek researchers, unable to afford personal subscriptions to their favourite journals, are already considering reviving a practice that was common a decade or so ago — contacting friends and colleagues in foreign research centres and asking them to fax or e-mail articles.</div>
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<li style="list-style: disc; margin: 0px 9px 5px 36px; padding: 0px;"><a href="http://www.nature.com/doifinder/10.1038/494159a" style="color: #5c7996; text-decoration: none;">Europe scales back research plans</a></li>
<li style="list-style: disc; margin: 0px 9px 5px 36px; padding: 0px;"><a href="http://www.nature.com/doifinder/10.1038/486308a" style="color: #5c7996; text-decoration: none;">Cuts leave Greek heritage in ruins</a></li>
<li style="list-style: disc; margin: 0px 9px 5px 36px; padding: 0px;"><a href="http://www.nature.com/doifinder/10.1038/483015a" style="color: #5c7996; text-decoration: none;">Protests delay Greek university reform</a></li>
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For many readers of <i>Nature</i>, the hardship faced by Greek scientists will come as no surprise. The country is reeling from six straight years of recession and unprecedented austerity measures. More than one-quarter of Greek people are out of work.</div>
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I am one of them. I am a biologist with a PhD in biological chemistry from the Aristotle University of Thessaloniki. In 2003, I went to Spain to work as a postdoc at the National Centre of Biotechnology in Madrid. In 2008, I returned to Greece as a research scientist with the National Hellenic Research Foundation in Athens, on a succession of short-term contracts. In March 2011, I was elected assistant professor of cell biology at the faculty of medicine of the University of Thessaly in Larissa. But I never began work there: I am one of about 800 faculty members who are still waiting to take up appointments around the country because the government refuses to approve the budget necessary for their salaries. They are distinguished scientists, many with years of postdoctoral experience, who have been selected through a long and demanding process and have been appointed by the heads of their respective universities.</div>
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The departments that selected these 800 faculty members are struggling to teach their students. In 2011, for the first time in decades, the Ministry of Education placed no new university professors. The scientific and professional prospects of young scholars in Greece are evaporating; this will leave the country’s universities lifeless and impotent. Budgets for research institutes have been reduced by 30%. The 2013 education budget will cut funds by a further 14% and condemns Greece to scientific and educational dormancy.</div>
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“Human potential should be nourished by urgent government action.”</div>
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There are no signs that the Greek government understands that long-term commitment to funding science and education must be part of the strategy to boost economic growth. In 2007, even before the most recent cuts, university and research funding in Greece stood at 0.6% of gross domestic product in 2007, already far below the European Union average of 1.9%.</div>
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Wages of researchers and faculty members have been reduced by 20%. If someone tells you that the Greek economy fell because of giant public-sector salaries, tell them that the average monthly wage of a university lecturer here is now around €1,000 (US$1,300). Researchers and professors who have spent years building their careers are asking whether it was worth it.</div>
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Scientists have adapted. They have learned to use the bare minimum of expensive reagents. They have become skilled at working with their overcoats on when deliveries of heating oil fail to materialize.</div>
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But many young scientists are heading abroad. In 2010, about 120,000 Greek scholars lived and worked elsewhere, about one-tenth of the total. The number is now estimated at 150,000. The young, skilled workforce, a key factor for economic development, is disappearing exactly when society needs it most. I, too, am considering whether to leave. The situation in Greece, combined with plans by European Union leaders to cut the research and development budget, paints a bleak picture for future generations.</div>
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Greek science is worth investing in and worth saving. In 2012, against all the odds, the proportion of the country’s research that contributed to the top 1% of most-cited articles was 13th in the world, above Canada, Italy and France. This human potential should be nourished by urgent government action.</div>
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A good place to start is to resist calls from existing professors to raise their retirement age from 67 to 70. The change has been suggested as a short-term fix for academic departments stretched to breaking point by the hiring freeze and retirements. Such a move would eliminate any chance that the new professors will be placed, given that the national programme of fiscal stability calls for the public sector to be dramatically reduced by making only one appointment for every ten retirements. It would block the natural and necessary renewal of university personnel with new blood. It would further accentuate the rapid ageing of Greek universities and leave faculties as shells containing only a handful of older professors and next to no lecturing staff and young researchers. We know from evolutionary biology that such micro-societies soon become extinct.</div>
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<dl class="citation" style="background-color: white; color: #333333; font-family: arial, helvetica, clean, sans-serif; font-size: 14px; line-height: 23.90625px; margin: 0px 0px 10px; padding: 0px;"><dd class="journal-title" style="display: inline; font-style: italic; margin: 0px; padding: 0px 3px 0px 0px;">Nature</dd> <dd class="volume" style="display: inline; font-weight: bold; margin: 0px; padding: 0px 3px 0px 0px;">496,</dd> <dd class="page" style="display: inline; margin: 0px; padding: 0px 3px 0px 0px;">271</dd> <dd style="display: inline; margin: 0px; padding: 0px 3px 0px 0px;">(<time datetime="2013-04-18">18 April 2013</time>)</dd> <dd class="doi" style="background-image: url(data:image/gif; background-position: 0px 0.4ex; background-repeat: no-repeat no-repeat; display: inline; margin: 0px 0px 0px 4px; padding: 0px 3px 0px 10px;"><abbr style="border: 0px;" title="Digital Object Identifier">doi</abbr>:10.1038/496271a</dd></dl>
<dl class="citation" style="background-color: white; color: #333333; font-family: arial, helvetica, clean, sans-serif; font-size: 14px; line-height: 23.90625px; margin: 0px 0px 10px; padding: 0px;"><dd class="doi" style="background-image: url(data:image/gif; background-position: 0px 0.4ex; background-repeat: no-repeat no-repeat; display: inline; margin: 0px 0px 0px 4px; padding: 0px 3px 0px 10px;"><a href="http://www.nature.com/news/austerity-led-brain-drain-is-killing-greek-science-1.12813">http://www.nature.com/news/austerity-led-brain-drain-is-killing-greek-science-1.12813</a></dd></dl>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-88784842808382537522013-04-13T04:45:00.000-07:002013-04-13T04:45:11.447-07:00Going underground in search of dark matter strikes<div class="separator" style="clear: both; text-align: center;">
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THE chill hits me as soon as the door shuts. Then the floor starts to rumble. The lift I've just entered feels like an original from the late 1800s, when miners made the same trip in search of iron ore. But my guide and I (pictured above) are seeking a much more elusive substance: <a href="http://www.newscientist.com/special/instant-expert-dark-matter">dark matter</a>.<br /><a name='more'></a><br />The same stuff was in the spotlight last week due to a tentative sighting in space, but we head in the opposite direction and descend into the <a href="http://www.newscientist.com/article/mg20627551.800-wonder-lust-soudan-mine.html">Soudan Mine</a> in northern Minnesota, home to rival experiments CDMS and CoGeNT.<br /><br />Like their space-based counterpart, AMS, both are designed to detect weakly interacting massive particles, the favoured form of dark matter. But while AMS looks for positrons given off when WIMPs collide, the hope down here is that a WIMP will knock into a heavy atom in supercooled crystals, making the atom's nucleus recoil and sending out a signal. Hundreds of metres of rock above us protect the detectors from atmospheric particles that could mimic such a strike.<br /><br />My guide, Jeter Hall, works on the CDMS detector, which he shows me first. About eight layers of shielding surround the array of supercooled silicon and germanium crystals – including a layer of lead salvaged from shipwrecks – so the experiment takes up most of the room. CoGeNT's single, 440-gram germanium crystal sits in a room next door, in a smaller box covered with polyethylene and lead. In 2011, this detector <a href="http://www.newscientist.com/article/dn20434-second-experiment-hints-at-seasonal-dark-matter-signal.html">caught whiffs of a WIMP</a>weighing 7 gigaelectronvolts (GeV), but the signal was inconclusive.<br /><br />CDMS meanwhile saw two potential "events" over its last run in 2008 but these weren't sure-things. And, because it only looks for WIMPs weighing 100 GeV or more, it couldn't verify CoGeNT's result. CDMS has since been upgraded so it is sensitive below 10 GeV: results are due later this year.<br /><br />Lack of sensitivity in these detectors may explain why <a href="http://www.newscientist.com/blogs/shortsharpscience/2012/07/dark-matter-no-show-hobbles-el.html">WIMPs have evaded direct detection</a> so far. In one new model of dark matter, most WIMPs in our galaxy live in a diffuse spherical cloud, while about 15 per cent have been drawn into a disc, like a shadow Milky Way (see "<a href="http://www.newscientist.com/article/dn23372-twist-in-dark-matter-tale-hints-at-shadow-milky-way.html">Twist in dark matter tale hints at shadow Milky Way</a>"). WIMPs in this dense disc would be more likely to hit a detector but as they are keeping pace with Earth in its flight around the galaxy, they would collide with less energy than expected.<br /><br />If WIMPs keep failing to show up, could dark matter <a href="http://www.newscientist.com/article/dn23344-dark-matter-mri-could-boost-hunt-for-hidden-particle.html">be something entirely different</a>? "It can keep you up at night that the thing you're searching for might not be there at all," says Hall. "But it's compelling enough for me to vote with my feet and work on it anyway."<br /><br />This article appeared in print under the headline "Underground lab seeks dark particle strikes<div>
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<a href="http://www.newscientist.com/article/mg21829123.900-going-underground-in-search-of-dark-matter-strikes.html">http://www.newscientist.com/article/mg21829123.900-going-underground-in-search-of-dark-matter-strikes.html</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-87713679187426923192013-03-12T01:53:00.001-07:002013-03-12T01:56:01.243-07:00Hubble's Successor: The James Webb Space Telescope<div class="separator" style="clear: both; text-align: center;">
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<br />Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-19598631315980736142013-02-14T10:37:00.002-08:002013-02-14T10:37:42.845-08:00Radio signal-hunting astronomers find no alien life near Milky Way stars<div class="separator" style="clear: both; text-align: center;">
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After a hunt for Milky Way radio signals came up empty, the team
of astronomers behind it has <a href="http://arxiv.org/pdf/1302.0845v1.pdf">estimated</a> that
fewer than one in a million stars in the galaxy could have advanced
civilisations residing on their orbiting planets. <br />
<a name='more'></a><br />
The team, which used the Green Bank Telescope in West Virginia
to look for signals with a frequency range of between 1.1 and 1.9
GHz (the mobile phone and TV band range on Earth), has <a href="http://arxiv.org/abs/1302.0845">published a paper</a> online
revealing its findings -- or lack thereof -- and prediction.<br />
The project was headed up by Jill Tarter of the SETI (search for
extraterrestrial intelligence) Institute, who has spent the
majority of her career in astronomy seeking signs of life in the
Universe. With the advent of the planet-hunting Kepler telescope,
she and her University of California, Berkeley team set about
targeting 86 star systems found by it -- the stars were chosen for
either hosting planets within the habitable zone, having five or
more planets in their orbit or super-Earths with long orbits. By
the time the research was launched (from February to April 2011),
Kepler had already idenitified 1,235 exoplanets.<br />
Each star was targeted for about five minutes, to gather enough
radio emissions. The team then looked for evidence of narrow
bandwidths in the data of no more than 5 Hz -- at such intensity,
signals can only be artificially engineered (at least, that is, as
far we know). Sadly, no such signal was found and thus the team
states in the paper that it "identified no evidence of advanced
technology indicative of intelligent life".<br />
"We didn't find ET, but we were able to use this statistical
sample to, for the first time, put rather explicit limits on the
presence of intelligent civilisations transmitting in the radio
band where we searched," UC Berkeley astronomer Andrew Siemion said
<a href="http://newscenter.berkeley.edu/2013/02/08/intelligent-civilizations-rarer-than-one-in-a-million/">
in a statement</a>.<br />
There are plenty of reasons why existing signals may have not
been picked up, however. For instance, the telescope was only
powerful enough to pick up signals directed straight at it from the
1,000-light-year distance most of the planets were located. In the
future, the team would like to try out much stronger telescopes,
for instance the <a href="http://www.wired.co.uk/news/archive/2012-07/16/ska-telescope-antenna-building">
Square Kilometre Array, due to be finished in 2024</a>. The array
will, predicts Tarter and her team, "be perhaps 100 times more
sensitive than the GBT" and it therefore may not matter whether the
signal is directed straight at Earth. If they were to use SKA, and
a distant civilisation had the power to send out stronger signals,
life would be relatively easier to spot. <br />
Considering Kepler's only been up and running since 2009 and
it's already spotted <a href="http://www.wired.co.uk/news/archive/2013-01/21/kepler-glitch">
2,740 exoplanets</a> to date, there's plenty of scope for future
research and progress in the field. Even now, teams are making
adjustments to certainties Tarter and her team took for granted
while carrying out their research, For instance, the habitable zone
at which life can exist has recently been amended. According to <a href="http://www.scientificamerican.com/article.cfm?id=habitable-zone-redefined">
a study</a> from Penn State University, based on information from
two atmospheric databases that detail absorption rates of water and
carbon dioxide, the so-called Goldilocks zone at which a planet
could host liquid water was slightly off (in our solar system, it's
shifted from being between 0.95 and 1.67 astronomical units (the
distance from the Sun) to between 0.99 and 1.7 astronomical
units). <br />
"Right now I see it as a significant change," <a href="http://www.scientificamerican.com/article.cfm?id=habitable-zone-redefined">
commented Abel Mendez</a> of the University of Puerto Rico, who was
not involved in the study. "Many of those planets that we believe
were inside are now outside. But on the other side, it extends the
habitable zone's outer edge, so a few planets that are farther away
might fall inside the habitable zone now."<br />
It means some of the stars Tarter and her team focused on may
have potentially hosted planets outside of the habitable zone.<br />
To widen the parameters of its study, the team is hoping to look
into planetary pairs that might be communicating with one another,
and that routinely line up with Earth. Considering they've already
set their predictions at one in a million, what the likelihood of
finding two planets having a galactic chat is remains to be seen.
On the bright side, such a signal would have to be narrowly beamed
and powerful, predicts the team, so would be easier to spot.<br />
The SETI team does admit, however, that when it really comes
down to it we have no idea how a distant civilisation would
function and communicate -- it's all based on educated
predictions.<br />
"In particular, we can offer no argument that an advanced,
intelligent civilisation necessarily produces narrow-band radio
emission, either intentional or otherwise," reads the paper's
conclusion. "Thus we are probing only a potential subset of such
civilisations, where the size of the subset is difficult to
estimate." Earthlings, for instance, have been producing those
kinds of signals for only a mere fraction of their
existence. <br />
As things like the semiconductor business continue to boom,
however, progress is advancing, they say. <br />
"Within the next decade, we will have the ability to examine
significantly larger portions of the electromagnetic spectrum,
including instantaneous analysis of the entire 10 GHz of the
terrestrial microwave window. In addition to radio searches, new
technology will extend SETI into regions of the electromagnetic
spectrum never before observed with high sensitivity. Extending
searches to encompass much larger classes of signals is crucial to
producing robust and meaningful limits."<br />
<em>Image: <a href="http://www.shutterstock.com/">Shutterstock</a></em><br />
<br />
<em>Read more...</em><br />
<em><a href="http://www.wired.co.uk/news/archive/2013-02/08/aliens-are-one-in-a-million" target="_blank"> http://www.wired.co.uk/news/archive/2013-02/08/aliens-are-one-in-a-million</a></em><br />
<div class="separator" style="clear: both; text-align: center;">
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<em> </em>Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-65223964814342481102013-02-12T13:13:00.000-08:002013-02-12T13:15:38.066-08:00 Extreme life might be visible on colourful exoplanets <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQqxGhjJBJ7BVuuQbC-WQada-lCyo4fg0Zp9_gUSEhqqmk3hwYye3kZ6BSw8K0xTeet1RRDHTW4PsObw3b1WIADbOhyphenhyphenokBy9lNfIfYk3qU1JH8cHfZwTsh1W6pYcClYtblUXT_QPQIM0Y/s1600/%CE%BB%CE%B5%CE%B9%CF%87%CE%B7%CE%BD%CE%B5%CF%82.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="408" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQqxGhjJBJ7BVuuQbC-WQada-lCyo4fg0Zp9_gUSEhqqmk3hwYye3kZ6BSw8K0xTeet1RRDHTW4PsObw3b1WIADbOhyphenhyphenokBy9lNfIfYk3qU1JH8cHfZwTsh1W6pYcClYtblUXT_QPQIM0Y/s640/%CE%BB%CE%B5%CE%B9%CF%87%CE%B7%CE%BD%CE%B5%CF%82.jpg" width="640" /></a></div>
<div class="infuse">
Lichens and algae could be the first life forms we find on Earth-like exoplanets, by looking for their <a href="http://www.newscientist.com/article/dn7435-slime-worlds-may-reflect-signs-of-life.html">light signatures</a> in a planet's distinctive colouring.</div>
<div class="infuse">
Astronomers have found several <a href="http://www.newscientist.com/article/dn23144-closest-earthlike-planet-may-be-13-light-years-away.html">rocky worlds in the habitable zone</a>,
the region around a star where liquid water can exist on a planet's
surface, and many more are thought to exist. As telescopes get more
sensitive, we should be able to collect light reflected off such planets
and look for clues to their surface conditions.</div>
<a name='more'></a><br />
<div class="infuse">
Seen from space, Earth gives off a
large amount of near-infrared light, which is reflecting off the
chlorophyll in plants. We might see a similar <a href="http://www.newscientist.com/article/dn19889-could-we-detect-trees-on-other-planets.html">"red edge"</a> on distant exoplanets if they also host green vegetation.</div>
<div class="infuse">
But Siddharth Hegde and <a href="http://www.mpia-hd.mpg.de/homes/kaltenegger/Home.html">Lisa Kaltenegger</a>
of the Max Planck Institute for Astronomy in Heidelberg, Germany, think
it is possible that many rocky worlds will have extreme heat, dryness
or acidity, and that hardier life forms will dominate their surfaces. So
what would these organisms look like from a distance?</div>
<h3 class="crosshead">
Patterns of life</h3>
<div class="infuse">
To find out the pair looked at the
light reflected by some of Earth's more extreme life forms: lichens in
arid regions, bacterial mats in very hot water and red algae in acid
mine drainage. They calculated that seen from afar each type of organism
would create a unique colour pattern. Lichens, for instance, appear
more yellow than the algae or bacteria.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">Living on a neighbouring planet? <i>(Image: Don Johnston/Getty)</i></td></tr>
</tbody></table>
</div>
<div class="infuse">
Finding these patterns wouldn't
necessarily mean life is present, but it could be a step towards
narrowing down exoplanets for more detailed searches, the authors say.</div>
<div class="infuse">
It's an attractive idea, says <a href="http://nickcowan.com/">Nicolas Cowan</a>
of Northwestern University in Evanston, Illinois, and it is far more
likely that a given planet would contain microbial life than trees. But
the work has its limits, he cautions. For instance, atmospheres on other
planets may be very different from our own and could scatter light in
ways we wouldn't expect.</div>
<div class="infuse">
"Nature may be more creative than our little corner of the cosmos would have us believe," Cowan says.</div>
<div class="infuse">
Journal reference: <i>Astrobiology</i>, <a href="http://doi.org/kch">doi.org/kch</a></div>
<div class="infuse">
<br /></div>
<div class="infuse">
Read more</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn23155-extreme-life-might-be-visible-on-colourful-exoplanets.html" target="_blank"> http://www.newscientist.com/article/dn23155-extreme-life-might-be-visible-on-colourful-exoplanets.html</a></div>
<div class="separator" style="clear: both; text-align: center;">
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<div class="infuse">
<br /></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-69143021221348148122013-02-07T11:12:00.002-08:002013-02-07T11:12:43.835-08:00 What is life? The physicist who sparked a revolution in biology<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">Insights
from biology and computing built upon Schrödinger’s genius, changing
our view of life forever. Photograph: Rick Sammon/AP</td></tr>
</tbody></table>
<br />Matthew Cobb<br /> Seventy years ago, on 5 February 1943, the Nobel prizewinning quantum physicist Erwin Schrödinger gave the first of three public lectures at Trinity College, Dublin. His topic was an unusual one for a physicist: “What is Life?” The following year the lectures were turned into a book of the same name. <a name='more'></a><br /><br />One of Schrödinger’s key aims was to explain how living things apparently defy the second law of thermodynamics – according to which all order in the universe tends to break down. It was this that led my colleague Professor Brian Cox to use Schrödinger as the starting point of his BBC series Wonders of Life, leading to What is Life? shooting up the Amazon sales chart. <br /><br />But Schrödinger’s book contains something far more important than his attempt to fuse physics and biology. In that lecture 70 years ago, he introduced some of the most important concepts in the history of biology, which continue to frame how we see life. <br /><br />At a time when it was thought that proteins, not DNA, were the hereditary material, Schrödinger argued the genetic material had to have a non-repetitive molecular structure. He claimed that this structure flowed from the fact that the hereditary molecule must contain a “code-script” that determined “the entire pattern of the individual’s future development and of its functioning in the mature state”. <br /><br />This was the first clear suggestion that genes contained some kind of “code”, although Schrödinger’s meaning was apparently not exactly the same as ours – he did not suggest there was a correspondence between each part of the “code-script” and precise biochemical reactions. <br /><br />Historians and scientists have argued over the influence of Schrödinger’s lectures and the book that followed, but there can be no doubt that some of the key figures of 20th century science – James Watson, Francis Crick, Maurice Wilkins and others – were inspired to turn to biology by the general thrust of Schrödinger’s work. <br /><br />The role of the brilliant “code-script” insight is less clear. Reviewers of What is Life? in both Nature and the New York Times noted the novel phrase, but despite the fact that in 1944 Oswald Avery published clear evidence that DNA was the genetic material, virtually no one immediately began looking for – or even talking about – a molecular “code-script” in DNA, although Kurt Stern suggested that the code might involve grooves in a protein molecule, like the grooves in a vinyl disc. <br /><br />Part of the reason for this lack of immediate excitement and for Avery’s discovery not being widely accepted was that DNA was thought to be a “boring” molecule with a repetitive structure – exactly what Schrödinger had said a gene could not be. It took the work of Erwin Chargaff, inspired by Avery, to show that the proportion of the “bases” in the DNA molecule – generally presented by the letters A, T, C and G – differed widely from species to species, suggesting the molecule might not be so boring after all. <br /><br />As early as 1947, Chargaff suggested that the change of a single base “could produce far-reaching changes … it is not impossible that rearrangements of this type are among the causes of the occurrence of mutations.” The culmination of this line of work was Watson and Crick’s double helix model, which was based on the experimental data of Rosalind Franklin and Maurice Wilkins. <br /><br />But in 1947 there was a missing component in biological thinking about the nature of the code, one which was at the heart of Watson and Crick’s decisive interpretation of their discovery a mere six years later – “information”. That idea entered biology through some applied research carried out to aid the war effort. <br /><br />In 1943, the US National Research and Development Committee set up a group of scientists to study “fire control” – how to ensure accurate anti-aircraft fire, by the control of information from radar, visual tracking and range-finding. Two of the men involved in this project were Claude Shannon, a mathematician who developed what became known as “information theory” to understand how signals were processed, and Norbert Wiener, who thought there were parallels between control systems in machines and in organisms, and who coined the term “cybernetics”. <br /><br />The first person to argue that a gene contains information was the co-founder of cybernetics, John von Neumann. In 1948, von Neumann described a gene as a “tape” that could program the organism – like the “universal Turing machine” described in 1936 by Alan Turing (intriguingly, Turing had discussed it with Shannon while working in New York in 1944). A few years later in 1950, geneticist Hans Kalmus deliberately applied cybernetic thinking to the problem of heredity and suggested that a gene was a “message”. <br /><br />Cybernetics briefly became wildly popular, filling the pages of broadsheet newspapers all over the world and encouraging biologists to look for feedback loops in living things. Following the 1948 publication of Shannon’s dense book Information Theory (co-authored by Warren Weaver, who had chaired the fire control group and also coined the term “molecular biology”), the abstract concept of information percolated into the scientific mainstream. <br /><br />Although the term had a precise meaning for Shannon, in the hands of the biologists it turned into a vague metaphor, a way of thinking about something they as yet had no real understanding of: the nature of the gene. <br /><br />Ten years after Schrödinger’s brilliant insight, Watson and Crick’s second 1953 article on the structure of DNA provided the world with the key to the secret of life, casually employing the new concepts that had been created by cybernetics and propelling biology into the modern age with the words: “it therefore seems likely that the precise sequence of the bases is the code which carries the genetical information.” <br /><br />These prophetic words – shorn of the conditional opening phrase – are uttered in biology classes all over the world, every single day. <br /><br />In a decade of tumultuous discovery, insights from biology and computing built upon Schrödinger’s genius, changing our view of life forever. Life had become information, genes were the bearers of that information, carrying it in a tiny, complex code inside every cell of our bodies. And the breakthrough began in a Dublin lecture theatre 70 years ago this week.<br />
<br />
Read more: <a href="http://www.guardian.co.uk/science/blog/2013/feb/07/wonders-life-physicist-revolution-biology" target="_blank">www.guardian.co.uk</a>Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-55407416247273607712013-01-27T00:50:00.001-08:002013-01-27T00:50:30.959-08:00 A theory of everything won't provide all the answers <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">"Dark matter and dark energy – these are not crazy ingredients we're adding"</td></tr>
</tbody></table>
<div class="infuse">
<i>We shouldn't be obsessed with finding a theory of everything, says <b>Lisa Randall</b>, one of the world's most prominent theoretical physicists </i></div>
<div class="infuse">
<b>Doesn't every physicist dream of one neat theory of everything?</b><br />There
are lots of physicists! I don't think about a theory of everything when
I do my research. And even if we knew the ultimate underlying theory,
how are you going to explain the fact that we're sitting here? Solving
string theory won't tell us how humanity was born.</div>
<a name='more'></a><br />
<div class="infuse">
<b>So is a theory of everything a myth?</b><br />It's
not that it's a fallacy. It's one objective that will inspire progress.
I just think the idea that we will ever get there is a little bit
challenging.</div>
<div class="infuse">
<b>But isn't beautiful mathematics supposed to lead us to the truth?</b><br />You
have to be careful when you use beauty as a guide. There are many
theories people didn't think were beautiful at the time, but did find
beautiful later - and vice versa. I think simplicity is a good guide:
the more economical a theory, the better.</div>
<div class="infuse">
<b>Is it a problem, then, that our best theories of particle physics and cosmology are so messy?</b><br />We're trying to describe the universe from 10<sup>27</sup> metres down to 10<sup>-35</sup>
metres, so it's not surprising there are lots of ingredients. The idea
that the stuff we're made of should be everything seems quite
preposterous. Dark matter and dark energy - these are not crazy
ingredients we're adding.</div>
<div class="infuse">
<b>Did the discovery of the Higgs boson - the "missing ingredient" of particle physics - take you by surprise last July?</b><br />I
was surprised that the Large Hadron Collider experiments reached that
landmark. I thought the teams would say something very affirming but the
announcement of the discovery was amazing. It was a feat of engineering
that they got the collision rate up to what it had to be, and the
experiments did a better job at analysing the data.</div>
<div class="infuse">
<b>Are you worried that the Higgs is the only discovery so far at the LHC?</b><br />I'm
not worried that nothing else exists. But I am worried that the LHC
might have too low an energy. Had the Superconducting Super Collider
been built in Texas, it would have had almost three times the energy.
There is a distinct possibility we'll discover things when the LHC's
energy is nearly doubled next year. But it's too early to see signs of
warped extra dimensions - they will take longer to find.</div>
<div class="infuse">
<b>What would an extra dimension look like?</b><br />The
best signature of the warped extra dimensions would be seeing a
so-called Kaluza-Klein particle. These are partners of the particles
that we know about but they get their momentum from extra dimensions.
They would look to us like heavy particles with properties similar to
the ones we know, but with bigger masses.</div>
<div class="infuse">
<b>What if we don't see one? Some argue that seeing nothing else at the LHC would be best, as it would motivate new ideas.</b><br />I
don't know what dream world they are living in. It would be very hard
to make the argument to build a higher energy machine based on the fact
that you didn't see something.</div>
<div class="infuse">
<br /></div>
<div class="infuse">
<br /></div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21729000.300-a-theory-of-everything-wont-provide-all-the-answers.html" target="_blank">http://www.newscientist.com/article/mg21729000.300-a-theory-of-everything-wont-provide-all-the-answers.html</a></div>
<div class="infuse">
<br /></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-14249222449313761332013-01-05T14:12:00.002-08:002013-01-05T14:12:50.009-08:00 Cloud of atoms goes beyond absolute zero <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6QHPBLwh2kYctEEXXWFl3qrvOO_dIzFITKZRg0Vo3EDRveZn76io9ellMwCMbAPaRpRQn5aLdwrgvJBCzqC89i_Efzs1mI9W_k0zjCshyHCXnFF2IAVJP6NbpUMrjxuABaVnlC-Mad1g/s1600/dn23042-1_300.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="305" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6QHPBLwh2kYctEEXXWFl3qrvOO_dIzFITKZRg0Vo3EDRveZn76io9ellMwCMbAPaRpRQn5aLdwrgvJBCzqC89i_Efzs1mI9W_k0zjCshyHCXnFF2IAVJP6NbpUMrjxuABaVnlC-Mad1g/s400/dn23042-1_300.jpg" width="400" /></a></div>
<div class="infuse">
Nothing is colder than absolute zero, so it seems
nonsensical to talk about negative temperature – but now there is a
substance that must have just that. The revelation could shake up our
ideas about temperature and help us understand strange entities such as
dark energy, as well as the interactions of subatomic particles.</div>
<a name='more'></a><br />
<div class="infuse">
Although we're used to talking about
negative temperatures, such as −10°C, all temperatures on an ordinary
thermometer are actually positive when measured in kelvin, the
scientific temperature scale that starts at absolute zero (−273.15°C).</div>
<div class="infuse">
On the kelvin scale, temperature is
determined by the kinetic energy of particles, so a gas of slow
particles is colder than a gas of fast-moving ones. Absolute zero
corresponds to the point at which particles stop moving completely,
which is why nothing can be colder.</div>
<div class="infuse">
That does not tell the whole story,
however. Temperature also depends on the way in which the particle
energies are distributed within the gas, which determines their entropy,
or disorder.</div>
<h3 class="crosshead">
Energy landscape</h3>
<div class="infuse">
Above absolute zero, adding more
energy corresponds to an increase in entropy. Picture a hill next to a
valley (see image) with the height of the landscape corresponding to the
energy of a particle – and the chance of finding a particle at a
certain height representing entropy. At absolute zero, particles are
motionless and all have no energy so are all at the bottom of the
valley, giving a minimum entropy.</div>
<div class="infuse">
As the gas heats up, the average
energy of the particles increases, with some gaining lots of extra
energy but most just a small amount. Spread along the side of the hill,
now the particles have different energies, so entropy is higher.</div>
<div class="infuse">
According to temperature's entropic
definition, the highest positive temperature possible corresponds to the
most disordered state of the system. This would be an equal number of
particles at every point on the landscape. Increase the energy any
further and you'd start to lower the entropy again, because the
particles wouldn't be evenly spread. As a result, this point represents
the end of the positive temperature scale.</div>
<div class="infuse">
In principle, though, it should be
possible to keep heating the particles up, while driving their entropy
down. Because this breaks the energy-entropy correlation, it marks the
start of the negative temperature scale, where the distribution of
energies is reversed – instead of most particles having a low energy and
a few having a high, most have a high energy and just a few have a low
energy. The end of this negative scale is reached when all particles are
at the top of the energy hill.</div>
<div class="infuse">
The resulting thermometer is
mind-bending with a scale that starts at zero, ramps up to plus
infinity, then jumps to minus infinity before increasing through the
negative numbers until it reaches negative absolute zero, which
corresponds to all particles sitting at the top of the energy hill.</div>
<h3 class="crosshead">
Cold atoms</h3>
<div class="infuse">
"The temperature scale as we know it starts at zero and goes up to infinity, but it doesn't stop there," says <a href="http://www.quantum-munich.de/people/person-details/pers/10/">Ulrich Schneider</a> of the Ludwig Maximilian University of Munich in Germany.</div>
<div class="infuse">
To enter the negative realm, Schneider
and his colleagues began by cooling atoms to a fraction above absolute
zero and placing them in a vacuum. They then used lasers to place the
atoms along the curve of an energy valley with the majority of the atoms
in lower energy states. The atoms were also made to repel each other to
ensure they remained fixed in place.</div>
<div class="infuse">
Schneider's team then turned this
positive temperature system negative by doing two things. They made the
atoms attract and adjusted the lasers to change the atoms' energy
levels, making the majority of them high-energy, and so flipping the
valley into an energy hill. The result was an inverse energy
distribution, which is characteristic of negative temperatures.</div>
<div class="infuse">
The atoms can't lose energy and "roll
down" this hill because doing so would require them to increase their
kinetic energy and this is not possible because the system is in a
vacuum and there is no outside energy source. "We create a system with a
lot of energy, but the particles cannot redistribute their energy so
they have to stay on top of the hill," says Schneider.</div>
<h3 class="crosshead">
Dark temperature</h3>
<div class="infuse">
Cold atoms are already used to
simulate the interactions of some subatomic particles. The new negative
temperature set-up could be used to create simulated interactions that
are not possible with positive temperatures. "They are a new technical
tool in the business of quantum simulations," says Schneider.</div>
<div class="infuse">
Negative temperature may also have
implications for cosmology. Dark energy, thought to explain the
accelerating expansion of the universe, exerts negative pressure, which
suggests it might have negative temperature – Schneider is currently
discussing the idea with cosmologists.</div>
<div class="infuse">
"It is amazing experimental work," says <a href="http://www.mosk.net/">Allard Mosk</a> of the University of Twente in the Netherlands, who <a href="http://www.newscientist.com/article/mg20827893.500-how-to-create-temperatures-below-absolute-zero.html">originally outlined the theory behind the experiment in 2005</a>.</div>
<div class="infuse">
Learning more about how negative
temperature systems interact both with themselves and with positive
temperatures might allow us to build ultra-efficient heat engines, but
these are far off, he says. "I don't think this will immediately give us
new devices, but it will give us a deeper understanding about what
temperature really is."</div>
<div class="infuse">
Journal reference: <i>Science</i>, 10.1126/science.1227831</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn23042-cloud-of-atoms-goes-beyond-absolute-zero.html" target="_blank"> http://www.newscientist.com/article/dn23042-cloud-of-atoms-goes-beyond-absolute-zero.html</a></div>
<div class="infuse">
<br /></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-74466810473687971062012-12-25T00:46:00.003-08:002012-12-25T00:46:43.692-08:00 2012 review: The year in the physical sciences <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhU1deje9rp3aEinWQ5U9lVNmXrJZlSVom4rHqYFGPfDI_YzwekRN9VMm0ZfSWFs1hrxmaerf_SJudboORPNd8v5GDoKPw7JAZDFWzLhkdfR7ClsqSYwHIBU6Zex94pKLHD9HZL8TM6bGI/s1600/universe.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="305" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhU1deje9rp3aEinWQ5U9lVNmXrJZlSVom4rHqYFGPfDI_YzwekRN9VMm0ZfSWFs1hrxmaerf_SJudboORPNd8v5GDoKPw7JAZDFWzLhkdfR7ClsqSYwHIBU6Zex94pKLHD9HZL8TM6bGI/s400/universe.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="lowlight">
Even the universe probably isn't eternal <i>(Image: Jupe/Alamy)</i></div>
</td></tr>
</tbody></table>
<div class="infuse">
You may have thought that 2011 was the year of amazing
physics, but 2012 soundly beats it. Whereas last year threw up
intriguing questions, 2012 was a year of answers, some enabled by
marvels of engineering.</div>
<a name='more'></a> A boson resembling the Higgs popped up at the
largest particle accelerator ever built, confirming hints first glimpsed
at the end of 2011. Statistics were crucial to that discovery and
proved vital even in the US presidential elections. But 2012 brought
lessons as well as triumphs: what looked in 2011 like neutrinos breaking
the cosmic speed limit was revealed to be an engineering flaw. Now,
relive the roller coaster.<br />
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21528734.000-beyond-higgs-deviant-decays-hint-at-exotic-physics.html"><b>Beyond Higgs: Deviant decays hint at exotic physics</b></a><br />The
world's most wanted particle has shown up at last, and surprises in its
behaviour could help transcend the limits of the standard model of
particle physics</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21328544.700-neutrino-speed-errors-dash-exotic-physics-dreams.html"><b>Neutrino speed errors dash exotic physics dreams</b></a><br />Extra
dimensions, time travel and tachyons all seemed a little more likely in
the wake of claims that subatomic particles called <a href="http://www.newscientist.com/special/neutrinos" target="ns">neutrinos</a> had moved faster than light – but the universe just returned to its slightly more mundane self</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21628914.800-if-you-want-to-be-president-hire-geeks-not-pundits.html"><b>If you want to be president, hire geeks not pundits</b></a><br />As
the US re-elected President Barack Obama, mathematics fans crowned
their own king: statistician Nate Silver. Elections of the future could
be won by the party with the best stats</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21328474.400-why-physicists-cant-avoid-a-creation-event.html"><b>Why physicists can't avoid a creation event</b></a><br />The big bang may not have been the beginning of everything – but new calculations suggest we still need a cosmic starter gun</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn22256-fiendish-abc-proof-heralds-new-mathematical-universe.html"><b>Fiendish 'ABC proof' heralds new mathematical universe</b></a><br />Solving
this 25-year-old puzzle meant tearing up and rebuilding the basic
elements of number theory – and the result could prise open other
enigmas</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21328484.000-deathdefying-time-crystal-could-outlast-the-universe.html"><b>Death-defying time crystal could outlast the universe</b></a><br />Don't
take the heat death of the universe lying down – a time crystal,
symmetrical in time rather than space, would have the power to survive
even the end of the universe</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21428641.500-truth-of-the-matter-the-majorana-particle-mystery.html"><b>Truth of the matter: The Majorana particle mystery</b></a><br />Can
a single entity be matter and antimatter at the same time? The idea was
first aired 80 years ago, but now matter-antimatter hybrids seem to
have been sighted trapped in the innards of a solid superconductor</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn22336-quantum-measurements-leave-schrodingers-cat-alive.html"><b>Quantum measurements leave Schrödinger's cat alive</b></a><br />Physicists
have probed a delicate quantum state without destroying it – the
equivalent of taking a peek at the metaphorical cat without killing it</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn21597-us-judge-rules-that-you-cant-copyright-pi.html"><b>US judge rules that you can't copyright pi</b></a><img alt="Movie Camera" class="artxicon" src="http://www.newscientist.com/img/icon/artx_video.gif" title="Contains video content" /><br />The
mathematical constant pi continues to infinity, but an extraordinary
lawsuit that centred on this most beloved string of digits has come to
an end – on <a href="http://www.newscientist.com/article/dn21589-constants-clash-on-pi-day.html">Pi Day</a></div>
<div class="infuse">
<a href="http://www.newscientist.com/article/mg21428625.400-move-over-graphene-silicene-is-the-new-star-material.html"><b>Move over graphene, silicene is the new star material</b></a><br />After
only a few years basking in the limelight, wonder material graphene now
has a silicon-based competitor that could be more compatible with
electronic devices</div>
<div class="infuse">
<br /></div>
<div class="infuse">
Read more...</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn23030-2012-review-the-year-in-the-physical-sciences.html" target="_blank"> http://www.newscientist.com/article/dn23030-2012-review-the-year-in-the-physical-sciences.html</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-33138525296774723952012-12-15T13:55:00.002-08:002012-12-15T13:55:25.214-08:00 Einstein was first to dream up dark energy <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgloekWpRv8cl1TtbrdlqgcPckY-lvMqlL2IqtA1m6mWTHbkQ7F8rrwCBjd0LB7ozIhl32h4CO2TXJkfGoL6cZfC1FVXFO5HTgOumUK1OwAcRqrIY7OmAEY2Q7Bczix9T1vdUCfGrJVXVk/s1600/dn22608-1_300.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="305" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgloekWpRv8cl1TtbrdlqgcPckY-lvMqlL2IqtA1m6mWTHbkQ7F8rrwCBjd0LB7ozIhl32h4CO2TXJkfGoL6cZfC1FVXFO5HTgOumUK1OwAcRqrIY7OmAEY2Q7Bczix9T1vdUCfGrJVXVk/s400/dn22608-1_300.jpg" width="400" /></a></div>
<br /><br />For geniuses, even blunders are triumphs in disguise. A dialogue between Albert Einstein and Erwin Schrödinger, pictured, suggests the pair stumbled upon the idea of <a href="http://www.newscientist.com/special/dark-energy">dark energy</a> 80 years before its time, while toying with what they thought was an ugly fudge factor.<a name='more'></a><br />In 1917, Einstein's novel equations of space-time had geometric terms on the left and energy on the right. A constant on the left kept the universe steady, suiting observations at the time. But in 1929, it became clear that the universe is expanding and Einstein dubbed the constant "the biggest mistake of my life". <br /><br />Now historian Alex Harvey of New York University has re-analysed papers from the physicists, published in 1918. In one Schrödinger toyed with Einstein's equations, moving the constant from the left to the right. <br /><br />The simple move transformed the constant from part of the geometry of space-time to a source of energy for the universe. "While mathematically it doesn't make any difference, physically it does," says Harvey. <br /><br />Einstein responded, rather cheekily, that the properties of this new energy term were either nothing or demand a "non-observable negative density in interstellar spaces".<h3 class="crosshead">
Pandora's Box</h3>
<div class="infuse">
"That turns out to be dark energy,"
Harvey says – which only emerged again in 1998 to explain the universe's
accelerating expansion.</div>
<div class="infuse">
Cosmologists have been seeking to pin
down dark energy's true nature ever since. The discovery that the
universe's expansion is accelerating <a href="http://www.newscientist.com/article/dn21006-stillmysterious-dark-energy-takes-physics-nobel.html">garnered three physicists the 2011 Nobel prize in physics</a>.</div>
<div class="infuse">
If Einstein had followed the
mathematics, he could have predicted yet another Nobel-worthy idea from
first principles. Instead, he dismissed his notion almost as soon as he
conceived of it. "The course taken by Herr Schrödinger does not appear
possible to me because it leads too deeply into the thicket of
hypotheses," Einstein wrote.</div>
<div class="infuse">
"He simply pointed out that you're
opening up a Pandora's Box here," says Harvey. "It's either trivial, or
you have a headache. That headache historically turned out to be dark
energy."</div>
<div class="infuse">
Harvey thinks Einstein was mildly
irritated by Schrödinger's mathematical games. "His language indicates a
certain degree of annoyance," he adds.</div>
<div class="infuse">
<br /></div>
<div class="infuse">
Read more...</div>
<div class="infuse">
<a href="http://www.newscientist.com/article/dn22608-einstein-was-first-to-dream-up-dark-energy.html" target="_blank"> http://www.newscientist.com/article/dn22608-einstein-was-first-to-dream-up-dark-energy.html</a></div>
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-84791548544965108522012-12-13T11:35:00.003-08:002012-12-13T11:35:41.657-08:00Is Quantum Reality Analog after All? <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPUKviuf79acRz3NHVgcdX1yrKwRkVthB1Io9qDwruvpjeCEuKHkogs4AoRfyN7bb7yFdeVwd-dRfFOxK_b03Z_pvHSMB9fpayVdiuQTDtlCgKGLJLB2BrqPUldv5fuxb080gH28_R6wQ/s1600/the-unquantum-quantum_2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPUKviuf79acRz3NHVgcdX1yrKwRkVthB1Io9qDwruvpjeCEuKHkogs4AoRfyN7bb7yFdeVwd-dRfFOxK_b03Z_pvHSMB9fpayVdiuQTDtlCgKGLJLB2BrqPUldv5fuxb080gH28_R6wQ/s1600/the-unquantum-quantum_2.jpg" /></a></div>
<span style="font-weight: bold;"> </span>Last year the Foundational
Questions Institute's third essay contest posed the following question
to physicists and philosophers: “Is Reality Digital or Analog?” <br />
<a name='more'></a>The
organizers expected entrants to come down on the side of digital. After
all, the word “quantum” in <a href="http://www.scientificamerican.com/topic.cfm?id=quantum-physics">quantum physics</a>
connotes “discrete” —hence, “digital”. Many of the best essays held,
however, that the world is analog. Among them was the entry by David
Tong, who shared the second-place prize. The article here is a version
of his essay.<br />
In the late 1800s the famous german mathematician Leopold Kronecker
proclaimed, “God made the integers, all else is the work of man.” He
believed that whole numbers play a fundamental role in mathematics. For
today's physicists, the quote has a different resonance. It ties in with
a belief that has become increasingly common over the past several
decades: that nature is, at heart, discrete—that the building blocks of
matter and of spacetime can be counted out, one by one. This idea goes
back to the ancient Greek atomists but has extra potency in the digital
age. Many physicists have come to think of the natural world as a vast
computer described by discrete bits of information, with the laws of
physics an algorithm, like the green digital rain seen by Neo at the end
of the 1999 film <i>The Matrix</i>.<br />
<br />
Read more...<br />
<a href="http://news.feedzilla.com/en_us/stories/266404069?count=20&q=physics&client_source=feedzilla_widget&order=relevance&format=json&sb=1" target="_blank"> http://news.feedzilla.com/en_us/stories/266404069?count=20&q=physics&client_source=feedzilla_widget&order=relevance&format=json&sb=1</a>Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-43698294755349065782012-12-06T10:01:00.002-08:002012-12-06T10:05:02.412-08:00 Common Physics Misconceptions <div class="separator" style="clear: both; text-align: center;">
<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.youtube.com/embed/IM630Z8lho8?feature=player_embedded' frameborder='0'></iframe></div>
<br />Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-57774940227297284002012-11-27T01:05:00.000-08:002012-11-27T01:05:01.832-08:00 Full Moon, Partial Eclipse, and Jupiter <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUMoGmQr9bbUJyYpmW2cyn1kTsppjvAEIy6vM6A-4mER33aoofHiYJ45Dphe-LoAr4Z1Sj6_IExt8Zbsf6faRD3ORGllkFlHjZ89JvxH8S31KoQ7NTE94rAR8ZAe6Abs54Ets1Ai01fNI/s1600/Webvic12_Nov27ev.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUMoGmQr9bbUJyYpmW2cyn1kTsppjvAEIy6vM6A-4mER33aoofHiYJ45Dphe-LoAr4Z1Sj6_IExt8Zbsf6faRD3ORGllkFlHjZ89JvxH8S31KoQ7NTE94rAR8ZAe6Abs54Ets1Ai01fNI/s400/Webvic12_Nov27ev.jpg" width="252" /></a></div>
This week we are presented with a collection of celestial alignments that are quite visible in an urban setting. <br />
<a name='more'></a>The Moon reaches full phase on Tuesday, and will pass through the busy area of the night sky near the constellation Orion, the beautiful star cluster known as the <a href="http://en.wikipedia.org/wiki/Pleiades">Pleiades</a>, and the bright planet Jupiter (on Wednesday). As it does, take a closer look with a pair of binoculars or simple telescope, since these objects will be easy to locate and are engaging to view up close.<br /> <br /> The morning of Wednesday November 28th, the Moon touches the edge of Earth's shadow in space, creating a faint darkening of the northern limb of the Moon, also known as a <a href="http://eclipse.gsfc.nasa.gov/LEplot/LEplot2001/LE2012Nov28N.pdf">Partial Eclipse</a>. For San Francisco and the western US, the Moon's darkening will be most visible just before sunrise, during the 6:00 am hour.<br />
<br />
<br />
Read more...<br />
<a href="http://urbanastronomer.blogspot.gr/2012/11/full-moon-partial-eclipse-and-jupiter.html">http://urbanastronomer.blogspot.gr/2012/11/full-moon-partial-eclipse-and-jupiter.html</a><br />
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-46527062758907236982012-11-22T07:06:00.000-08:002012-11-22T07:06:10.732-08:00 Climate change may supersize sweet potatoes <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvDyJvDZz2eqrEaKeaJGY9FC2rd52v-5ocJxps3RvEIHYMHxEZ5aU9rlRMm0HIK71SVpdUFZ0OmiDr4txf-aLGaA0BB1dq8yahRdln-hx3WK_xjG5DSLsrNNqRsDChom0Nsmp7J-RMmVk/s1600/potato.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="305" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvDyJvDZz2eqrEaKeaJGY9FC2rd52v-5ocJxps3RvEIHYMHxEZ5aU9rlRMm0HIK71SVpdUFZ0OmiDr4txf-aLGaA0BB1dq8yahRdln-hx3WK_xjG5DSLsrNNqRsDChom0Nsmp7J-RMmVk/s400/potato.jpg" width="400" /></a></div>
<div class="infuse">
RISING levels of carbon dioxide in the atmosphere may
have a silver lining: doubling the size of the sweet potato, the fifth
most important food crop in the developing world.</div>
<div class="infuse">
Most studies of the effects of higher atmospheric CO<sub>2</sub>
on crops have shown rising yields of rice, </div>
<a name='more'></a>wheat and soy. The hardy
sweet potato is increasingly becoming a staple in Africa and Asia,
producing "more edible energy per hectare per day than wheat, rice or
cassava", according to research group the <a href="http://cipotato.org/">International Potato Center</a>.<br />
<div class="infuse">
<a href="http://www.soest.hawaii.edu/GG/FACULTY/jahren/">Hope Jahren</a> at the University of Hawaii at Manao and colleagues grew the plants at four CO<sub>2</sub>
concentrations: the current level of 390 parts per million, as well as
760, 1140 and 1520 ppm. The Intergovernmental Panel on Climate Change
predicts that atmospheric CO<sub>2</sub> levels will be between 500 and 1000 ppm by the year 2100.</div>
<div class="infuse">
For the least extreme scenario at 760 ppm, the team found the tubers grew up to 96 per cent larger.</div>
<div class="infuse">
The team is now testing their nutrient
content. "Are these sweet potatoes any more nutritious," asks team
member Ben Czeck, "or do you have to eat twice as many to get the
nutrients needed?" Crucially, previous studies revealed the protein
content in wheat, rice, barley and potatoes <a href="http://www.newscientist.com/article/mg19726374.700-global-warming-could-harm-food-quality.html">dropped by 15 per cent</a> when grown under CO<sub>2</sub> levels double those of today.</div>
Czeck will present the work in December at the American Geophysical <a href="http://fallmeeting.agu.org/2012/">Union meeting</a> in San Francisco<br />
<br />
Read more...<br />
<a href="http://www.newscientist.com/article/mg21628924.300-climate-change-may-supersize-sweet-potatoes.html?cmpid=RSS|NSNS|2012-GLOBAL|online-news" target="_blank"> http://www.newscientist.com/article/mg21628924.300-climate-change-may-supersize-sweet-potatoes.html?cmpid=RSS|NSNS|2012-GLOBAL|online-news</a>Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-62814323033275146092012-11-22T07:01:00.004-08:002012-11-22T07:01:55.943-08:00Bridging Cities of Galaxies<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgygyf-ZNJH7AToHMZibzQeUN8q5Yp3YWvdiL9I9osDxpGedA1SKyt612Y0U8KE_ESwhwojWfSbnHS51GLiQP7M5NecDYm9BCf0pjGdCwtfgb6DypliElOHrUa_Al7OWLkByC7Zbd49Fck/s1600/%CE%93%CE%B1%CE%BB%CE%B1%CE%BE%CE%B9%CE%B1%CE%BA%CE%B7+%CE%B3%CE%AD%CF%86%CF%85%CF%81%CE%B1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgygyf-ZNJH7AToHMZibzQeUN8q5Yp3YWvdiL9I9osDxpGedA1SKyt612Y0U8KE_ESwhwojWfSbnHS51GLiQP7M5NecDYm9BCf0pjGdCwtfgb6DypliElOHrUa_Al7OWLkByC7Zbd49Fck/s640/%CE%93%CE%B1%CE%BB%CE%B1%CE%BE%CE%B9%CE%B1%CE%BA%CE%B7+%CE%B3%CE%AD%CF%86%CF%85%CF%81%CE%B1.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"> Image credits: Sunyaev–Zel’dovich effect: ESA Planck Collaboration; optical image: STScI Digitized Sky Survey</td></tr>
</tbody></table>
Planck has discovered a bridge of hot gas that connects galaxy clusters
Abell 399 (lower center) and Abell 401 (top left). The galaxy pair is
located about a billion light-years from Earth, and the gas bridge
extends approximately 10 million light-years between them. <br />
<a name='more'></a><br /><br /> The
image shows the two galaxy clusters as seen at optical wavelengths with
ground-based telescopes and through the Sunyaev-Zel'dovich effect (in
orange) with the Planck satellite. <br /><br /><br /><br />
<br />
Read more..<br />
<a href="http://www.nasa.gov/mission_pages/planck/multimedia/pia16466.html" target="_blank"> http://www.nasa.gov/mission_pages/planck/multimedia/pia16466.html</a>Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-70647588790376309292012-11-12T08:08:00.002-08:002012-11-12T08:08:22.731-08:00Nebula new photo<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6k5Np3EJFs2PR_nL5bEgTVrAeICd9OU_3uwNMSSDyyMQO6kZ6D5AE-EDRWX87RqnqZdGPtiVdtYbHz6WwOSSOi8RA9A8KDpQQmW7ftXgR7oGy0nyQx8wsADdw-ObCF3CL_P7r1YhGM9s/s1600/Nebula.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="410" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6k5Np3EJFs2PR_nL5bEgTVrAeICd9OU_3uwNMSSDyyMQO6kZ6D5AE-EDRWX87RqnqZdGPtiVdtYbHz6WwOSSOi8RA9A8KDpQQmW7ftXgR7oGy0nyQx8wsADdw-ObCF3CL_P7r1YhGM9s/s640/Nebula.jpg" width="640" /></a></div>
<br />
<span class="fbPhotosPhotoCaption" id="fbPhotoSnowliftCaption" tabindex="0"><span class="hasCaption">Australian
astrophotographer Dave Larkin used the Internet based Slooh Space
Camera's Canary Island 20'' robotic telescope to capture this photo of
the Lagoon Nebula</span></span>Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-22201917654796640662012-11-11T12:50:00.003-08:002012-11-11T12:50:55.770-08:00Solar Eclipses: An Observer’s Guide (Infographic) <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8RC4ZYfPjLpkomuCge4eKYYULbY3CGNvrJoYeSv2TlxnLcKvGwgxkfXPgVKsDdBCJEySfug3KyRJv1mkxne-6PKJe5j5MDP9eG_g8ARJ6HsFkXd8HBY3_KulAOx276ITOLfnV7Rq2cvY/s1600/solar-eclipses-120509c-02.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8RC4ZYfPjLpkomuCge4eKYYULbY3CGNvrJoYeSv2TlxnLcKvGwgxkfXPgVKsDdBCJEySfug3KyRJv1mkxne-6PKJe5j5MDP9eG_g8ARJ6HsFkXd8HBY3_KulAOx276ITOLfnV7Rq2cvY/s1600/solar-eclipses-120509c-02.jpg" /></a></div>
<br />Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0tag:blogger.com,1999:blog-571949102557218314.post-66564180868139473532012-11-10T03:25:00.000-08:002012-11-10T03:25:07.953-08:00 Big Idea Bring Back the "Cold Fusion" Dream <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoP5Emu-6l2Bw6HTwilnhqMLtF3doa5i0HNbVc1wpiG-Q0fyr4v0UoWl8cM9ntq70c4P_NBgTR7bNCj_lW_PzyZ7LrazovSbceZqm6zWeKpgT91Nt_21zdzk_Zi__j7yH7wvTazS8XGpQ/s1600/coldfusion.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoP5Emu-6l2Bw6HTwilnhqMLtF3doa5i0HNbVc1wpiG-Q0fyr4v0UoWl8cM9ntq70c4P_NBgTR7bNCj_lW_PzyZ7LrazovSbceZqm6zWeKpgT91Nt_21zdzk_Zi__j7yH7wvTazS8XGpQ/s320/coldfusion.jpg" width="314" /></a></div>
In 1989 <a class="external-link" href="http://en.wikipedia.org/wiki/Stanley_Pons">Stanley Pons</a> and <a class="external-link" href="http://www.telegraph.co.uk/news/obituaries/9465201/Martin-Fleischmann.html">Martin Fleischmann</a>
made a sensational claim that would have changed the world—had it been
true. They said they had achieved nuclear fusion at room temperature
using a simple tabletop device, thus creating a revolutionary clean
energy source they called “cold fusion.”<br />
<a name='more'></a><br />
Unfortunately for the University of Utah chemists, multiple attempts
to replicate their experiment over ensuing months failed. Cold fusion
was considered debunked, and it has lived beyond the fringe of
mainstream science ever since.<br />
Yet quietly, more than 20 years later, two of the world’s largest
mainstream scientific institutions—NASA and the European physics
research center CERN—have revisited the controversial energy-generating
experiment. A growing cadre of scientists now suspect that Pons and
Fleischmann’s observations were the result not of fusion but of more
plausible physical processes. Some are even cautiously optimistic that
those processes could be exploited to generate abundant amounts of clean
energy. “There’s enough evidence that says we need to look at this,”
says Joseph Zawodny, a physicist at NASA’s Langley Research Center in
Virginia.<br />
<br />
Read more...<br />
<a href="https://discovermagazine.com/2012/nov/27-big-idea-bring-back-the-cold-fusion-dream" target="_blank"> https://discovermagazine.com/2012/nov/27-big-idea-bring-back-the-cold-fusion-dream</a><br />
Δρ. Τίνα Νάντσουhttp://www.blogger.com/profile/12594965709904872905noreply@blogger.com0