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Message: <blockquote data-quote="priyade" data-source="post: 24181377" data-attributes="member: 565365"><img src="http://www.elakiri.com//www.elakiri.com//www.elakiri.com//www.elakiri.com//img.purch.com/h/1400/aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA3Mi8yNTcvb3JpZ2luYWwvQXJyb3dfSlBHLmpwZw==" alt="" class="fr-fic fr-dii fr-draggable " style="" /><img src="http://www.elakiri.com//www.elakiri.com//img.purch.com/h/1400/aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA3Mi8yNTcvb3JpZ2luYWwvQXJyb3dfSlBHLmpwZw==" alt="" class="fr-fic fr-dii fr-draggable " style="" />Was the universe created with a Big Bang 13.7 billion years ago, or has it been expanding and contracting for eternity? A new paper, inspired by alternative explanations of the physics of black holes, explores the latter possibility, and rejects a core tenet of the Big Bang hypothesis.The universal origin story known as the Big Bang postulates that, 13.7 billion years ago, our universe emerged from a singularity — a point of infinite density and gravity — and that before this event, space and time did not exist (which means the Big Bang took place at no place and no time).There is ample evidence to show that the universe did undergo an early period of rapid expansion — in a trillionth of a trillionth of a trillionth of a second, the universe is thought to have expanded by a factor of 1078 in volume. For one, the universe is still expanding in every direction. The farther away an object is, the faster it appears to move away from an observer, suggesting that space itself is expanding (rather than objects simply moving through space at a steady rate). [Big Bang Theory: 5 Weird Facts About the Universe's Birth]Another key piece of evidence is the cosmic microwave background (CMB), which is thought to be heat left over from this great cosmological event. It can be observed in every direction and has no single origin point. Scientists think the CMB began propagating through the universe about 380,000 years after the Big Bang, when atoms began to form and the universe became transparent, according to the European Space Agency. However, there is no direct evidence of the original singularity. (Collecting information from that first moment of expansion is impossible with current methods.) In the new paper, Brazilian physicist Juliano Cesar Silva Neves argues that the original singularity may never have existed.Any potential hints about the Big Bang are worth looking for, but the main question, according to experts, is whether the putative oscillatory pattern will be strong enough to detect. It might not be a clear-cut guillotine as advertised.If it does exist, the signal would appear in density variations across the universe. Imagine taking a giant ice cream scoop to the sky and counting how many galaxies wind up inside. Do this many times all over the cosmos, and you’ll find that the number of scooped-up galaxies will vary above or below some average. Now increase the size of your scoop. When scooping larger volumes of universe, you might find that the number of captured galaxies now varies more extremely than before. As you use progressively larger scoops, according to Chen, Loeb and Xianyu’s calculations, the amplitude of matter density variations should oscillate between more and less extreme as you move up the scales. “What we showed,” Loeb explained, is that from the form of these oscillations, “you can tell if the universe was expanding or contracting when the density perturbations were produced” — reflecting an inflationary or bounce cosmology, respectively.Regardless of which theory of cosmogenesis is correct, cosmologists believe that the density variations observed throughout the cosmos today were almost certainly seeded by random ripples in quantum fields that existed long ago.Because of quantum uncertainty, any quantum field that filled the primordial universe would have fluctuated with ripples of all different wavelengths. Periodically, waves of a certain wavelength would have constructively interfered, forming peaks — or equivalently, concentrations of particles. These concentrations later grew into the matter density variations seen on different scales in the cosmos today.But what caused the peaks at a particular wavelength to get frozen into the universe when they did? According to the new paper, the timing depended on whether the peaks formed while the universe was exponentially expanding, as in inflation models, or while it was slowly contracting, as in bounce models.If the universe contracted in the lead-up to a bounce, ripples in the quantum fields would have been squeezed. At some point the observable universe would have contracted to a size smaller than ripples of a certain wavelength, like a violin whose resonant cavity is too small to produce the sounds of a cello. When the too-large ripples disappeared, whatever peaks, or concentrations of particles, existed at that scale at that moment would have been “frozen” into the universe. As the observable universe shrank further, ripples at progressively smaller and smaller scales would have vanished, freezing in as density variations. Ripples of some sizes might have been constructively interfering at the critical moment, producing peak density variations on that scale, whereas slightly shorter ripples that disappeared a moment later might have frozen out of phase. These are the oscillations between high and low density variations that Chen, Loeb and Xianyu argue should theoretically show up as you change the size of your galaxy ice cream scoop.</blockquote>

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