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No Big Bang? Quantum equation predicts universe has no beginning
Feb 09, 2015 by Lisa Zyga feature
big bang
This is an artist’s concept of the metric expansion of space, where space (including hypothetical non-observable portions of the universe) is represented at each time by the circular sections. Note on the left the dramatic expansion (not to …more
(Phys.org) —The universe may have existed forever, according to a new model that applies quantum correction terms to complement Einstein’s theory of general relativity. The model may also account for dark matter and dark energy, resolving multiple problems at once.
The widely accepted age of the universe, as estimated by general relativity, is 13.8 billion years. In the beginning, everything in existence is thought to have occupied a single infinitely dense point, or singularity. Only after this point began to expand in a “Big Bang” did the universe officially begin.
Although the Big Bang singularity arises directly and unavoidably from the mathematics of general relativity, some scientists see it as problematic because the math can explain only what happened immediately after—not at or before—the singularity.
“The Big Bang singularity is the most serious problem of general relativity because the laws of physics appear to break down there,” Ahmed Farag Ali at Benha University and the Zewail City of Science and Technology, both in Egypt, told Phys.org.
Ali and coauthor Saurya Das at the University of Lethbridge in Alberta, Canada, have shown in a paper published in Physics Letters B that the Big Bang singularity can be resolved by their new model in which the universe has no beginning and no end.
Old ideas revisited
The physicists emphasize that their quantum correction terms are not applied ad hoc in an attempt to specifically eliminate the Big Bang singularity. Their work is based on ideas by the theoretical physicist David Bohm, who is also known for his contributions to the philosophy of physics. Starting in the 1950s, Bohm explored replacing classical geodesics (the shortest path between two points on a curved surface) with quantum trajectories.
In their paper, Ali and Das applied these Bohmian trajectories to an equation developed in the 1950s by physicist Amal Kumar Raychaudhuri at Presidency University in Kolkata, India. Raychaudhuri was also Das’s teacher when he was an undergraduate student of that institution in the ’90s.
Using the quantum-corrected Raychaudhuri equation, Ali and Das derived quantum-corrected Friedmann equations, which describe the expansion and evolution of universe (including the Big Bang) within the context of general relativity. Although it’s not a true theory of quantum gravity, the model does contain elements from both quantum theory and general relativity. Ali and Das also expect their results to hold even if and when a full theory of quantum gravity is formulated.
No singularities nor dark stuff
In addition to not predicting a Big Bang singularity, the new model does not predict a “big crunch” singularity, either. In general relativity, one possible fate of the universe is that it starts to shrink until it collapses in on itself in a big crunch and becomes an infinitely dense point once again.
Ali and Das explain in their paper that their model avoids singularities because of a key difference between classical geodesics and Bohmian trajectories. Classical geodesics eventually cross each other, and the points at which they converge are singularities. In contrast, Bohmian trajectories never cross each other, so singularities do not appear in the equations.
In cosmological terms, the scientists explain that the quantum corrections can be thought of as a cosmological constant term (without the need for dark energy) and a radiation term. These terms keep the universe at a finite size, and therefore give it an infinite age. The terms also make predictions that agree closely with current observations of the cosmological constant and density of the universe.
New gravity particle
In physical terms, the model describes the universe as being filled with a quantum fluid. The scientists propose that this fluid might be composed of gravitons—hypothetical massless particles that mediate the force of gravity. If they exist, gravitons are thought to play a key role in a theory of quantum gravity.
In a related paper, Das and another collaborator, Rajat Bhaduri of McMaster University, Canada, have lent further credence to this model. They show that gravitons can form a Bose-Einstein condensate (named after Einstein and another Indian physicist, Satyendranath Bose) at temperatures that were present in the universe at all epochs.
Motivated by the model’s potential to resolve the Big Bang singularity and account for dark matter and dark energy, the physicists plan to analyze their model more rigorously in the future. Their future work includes redoing their study while taking into account small inhomogeneous and anisotropic perturbations, but they do not expect small perturbations to significantly affect the results.
“It is satisfying to note that such straightforward corrections can potentially resolve so many issues at once,” Das said.
Explore further: Did the universe originate from a hyper-dimensional black hole?
More information: Ahmed Farag Ali and Saurya Das. “Cosmology from quantum potential.” Physics Letters B. Volume 741, 4 February 2015, Pages 276–279. DOI: 10.1016/j.physletb.2014.12.057. Also at: arXiv:1404.3093[gr-qc].
Saurya Das and Rajat K. Bhaduri, “Dark matter and dark energy from Bose-Einstein condensate”, preprint: arXiv:1411.0753[gr-qc].
Journal reference: Physics Letters B

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Did the universe originate from a hyper-dimensional black hole?
Sep 25, 2014 by Brian Koberlein, One Universe At A Time
Did the universe originate from a hyper-dimensional black hole?
Lately there’s been news of a radical new theory proposing that the universe began from a hyper-dimensional black hole. Most of the reports seem to stem from an article posted a while back on the Nature blog, which references the original paper. So let’s have a little reality check.
No one is abandoning the big bang model. The original paper hasn’t even been peer reviewed yet and the paper doesn’t present a radical new theory to overturn the big bang. What the paper is actually about is higher-dimensional gravitational theory.
The standard theory of gravity (general relativity) describes our universe as a geometry of three-dimensional space with one dimension of time. This is sometimes called 3 + 1 space, and it gives a very accurate description of the universe we observe. But theorists like to play around with alternative models to see how they differ from regular general relativity. They may look at 2 + 1 space, a kind of flatland with time, or 2 + 2, with two time dimensions. There isn’t necessarily anything “real” about these models, and there certainly isn’t any experimental evidence to support anything other than 3 + 1 gravity, but alternative models are useful because they help us gain a deeper understanding of general relativity. In this particular paper, the authors were exploring 4 + 1 gravity. That is, a five-dimensional universe with 4 spatial dimensions and 1 time.
Back in 2000, another team of authors proposed a model where our regular 3 + 1 gravity could be treated as a brane within a larger 4 + 1 universe. It is similar to the way a 2 + 1 universe could be imagined as a 2-dimensional surface (the brane) within our 3-dimensional space. In the 2000 paper, the authors showed that a particular 4 + 1 universe with a 3 + 1 brane could give rise to the type of gravity we actually see.
The new paper takes this model one step further. In it, the authors show that 4 + 1 gravity allows for the existence of black holes. So if a 4 + 1 universe had large stars, some of those stars could collapse into a 4-dimensional “hyper black hole”. Like black holes in regular general relativity, these hyper black holes would have a central “singularity” of extremely dense and hot matter/energy. The authors then went on to show that a hyper black hole with the right conditions could not only create a three-dimensional brane, but the new brane would look very similar to the early universe we actually observe.
In other words, if we imagine a five-dimensional 4 + 1 universe, and if such a universe could create stars that collapse into hyper black holes, and if a particular hyper black hole had the right energy, then it might be possible for for such a hyper black hole to produce a 3 + 1 brane-universe with a beginning that looks like a big bang. That’s a lot of ifs.
Just to be clear, this is good theoretical work. The model is interesting, and it shows a curious connection between the universe we observe and higher-dimensional gravity. It could also address some of the issues in cosmology, but it also predicts the universe is flat, which as I mentioned yesterday may not be the case. The authors note this problem, and are careful not to make broad claims. They also outline possible ways that such a model could be tested. This is what good theoreticians do.
But currently there is no experimental evidence to support higher-dimensions, much less hyper black holes. So don’t toss the big bang just yet.

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Could the famed “Big Bang” theory need a revision? A group of theoretical physicists suppose the birth of the universe could have happened after a four-dimensional star collapsed into a black hole and ejected debris.
Before getting into their findings, let’s just preface this by saying nobody knows anything for sure. Humans obviously weren’t around at the time the universe began. The standard theory is that the universe grew from an infinitely dense point or singularity, but who knows what was there before?
“For all physicists know, dragons could have come flying out of the singularity,” stated Niayesh Afshordi, an astrophysicist with the Perimeter Institute for Theoretical Physics in Canada who co-authored the new study.
So what are the limitations of the Big Bang theory? The singularity is one of them. Also, it’s hard to predict why it would have produced a universe that has an almost uniform temperature, because the age of our universe (about 13.8 billion years) does not give enough time—as far as we can tell—to reach a temperature equilibrium.
Most cosmologists say the universe must have been expanding faster than the speed of light for this to happen, but Ashford says even that theory has problems: “The Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on.”
Goodbye Big Bang, hello black hole? A new theory of the universe’s creation
Representation of the timeline of the universe over 13.7 billion years, from the Big Bang, through the cosmic dark ages and formation of the first stars, to the expansion in the universe that followed. Credit: NASA/WMAP Science Team
This is what the physicists propose:
The model they constructed has the three-dimensional universe floating as a membrane (or brane) in a “bulk universe” that has four dimensions. (Yes, this is making our heads hurt as well, so it might be easier to temporarily think of the brane as two-dimensional and the “bulk universe” as three-dimensional when trying to picture it.) You can read the more technical details in this 2000 paper on which the new theory is based.
So if this “bulk universe” has four-dimensional stars, these stars could go through the same life cycles as the three-dimensional ones we are familiar with. The most massive ones would explode as supernovae, shed their skin and have the innermost parts collapse as a black hole.
The 4-D black hole would have an “event horizon” just like the 3-D ones we are familiar with. The event horizon is the boundary between the inside and the outside of a black hole. There are a lot of theories of what goes on inside a black hole, although nothing has ever been observed.
In a 3-D universe, the event horizon appears as a two-dimensional surface. So in a 4-D universe, the event horizon would be a 3-D object called a hypersphere.
So basically, what the model says is when the 4-D star blows apart, the leftover material would create a 3-D brane surrounding a 3-D event horizon, and then expand.
The long and the short of it? To bring this back to things that we can see, it is clear from observations that the universe is expanding (and indeed is getting faster as it expands, possibly due to the mysterious dark energy). The new theory says that the expansion comes from this 3-D brane’s growth. But there is at least one limitation.
While the model does explain why the universe has nearly uniform temperature (the 4-D universe preceding it would have existed it for much longer), a European Space Agency telescope called Planck recently mapped small temperature variations in the cosmic microwave background, which is believed to be leftovers of the universe’s beginnings.
Goodbye Big Bang, hello black hole? A new theory of the universe’s creation
This artist’s impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus (The Centaur). New observations using the Very Large Telescope Interferometer …more
The new model differs from these CMB readings by about four percent, so the researchers are looking to refine the model. They still feel the model has worth, however. Planck shows that inflation is happening, but doesn’t show why the inflation is happening.
“The study could help to show how inflation is triggered by the motion of the universe through a higher-dimensional reality,” the researchers stated.
You can read more about their research on this prepublished Arxiv paper. The Arxiv entry does not specify if the paper has been submitted to any peer-reviewed scientific journals for publication.
Explore further: An improved model for star formation
More information: arxiv.org/abs/1309.1487
Journal reference: arXiv
Source: Universe Today
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Our universe may have emerged from a black hole in a higher-dimensional universe, propose a trio of Perimeter Institute researchers.
The big bang poses a big question: if it was indeed the cataclysm that blasted our universe into existence 13.7 billion years ago, what sparked it?
Three Perimeter Institute researchers have a new idea about what might have come before the big bang. It’s a bit perplexing, but it is grounded in sound mathematics, testable, and enticing enough to earn the cover story in Scientific American, called “The Black Hole at the Beginning of Time.”
What we perceive as the big bang, they argue, could be the three-dimensional “mirage” of a collapsing star in a universe profoundly different than our own.
“Cosmology’s greatest challenge is understanding the big bang itself,” write Perimeter Institute Associate Faculty member Niayesh Afshordi, Affiliate Faculty member and University of Waterloo professor Robert Mann, and PhD student Razieh Pourhasan.
Conventional understanding holds that the big bang began with a singularity – an unfathomably hot and dense phenomenon of spacetime where the standard laws of physics break down. Singularities are bizarre, and our understanding of them is limited.
“For all physicists know, dragons could have come flying out of the singularity,” Afshordi says in an interview with Nature.
The problem, as the authors see it, is that the big bang hypothesis has our relatively comprehensible, uniform, and predictable universe arising from the physics-destroying insanity of a singularity. It seems unlikely.
So perhaps something else happened. Perhaps our universe was never singular in the first place.
Their suggestion: our known universe could be the three-dimensional “wrapping” around a four-dimensional black hole’s event horizon. In this scenario, our universe burst into being when a star in a four-dimensional universe collapsed into a black hole.
In our three-dimensional universe, black holes have two-dimensional event horizons – that is, they are surrounded by a two-dimensional boundary that marks the “point of no return.” In the case of a four-dimensional universe, a black hole would have a three-dimensional event horizon.
In their proposed scenario, our universe was never inside the singularity; rather, it came into being outside an event horizon, protected from the singularity. It originated as – and remains – just one feature in the imploded wreck of a four-dimensional star.
The researchers emphasize that this idea, though it may sound “absurd,” is grounded firmly in the best modern mathematics describing space and time. Specifically, they’ve used the tools of holography to “turn the big bang into a cosmic mirage.” Along the way, their model appears to address long-standing cosmological puzzles and – crucially – produce testable predictions.
Of course, our intuition tends to recoil at the idea that everything and everyone we know emerged from the event horizon of a single four-dimensional black hole. We have no concept of what a four-dimensional universe might look like. We don’t know how a four-dimensional “parent” universe itself came to be.
But our fallible human intuitions, the researchers argue, evolved in a three-dimensional world that may only reveal shadows of reality.
They draw a parallel to Plato’s allegory of the cave, in which prisoners spend their lives seeing only the flickering shadows cast by a fire on a cavern wall.
“Their shackles have prevented them from perceiving the true world, a realm with one additional dimension,” they write. “Plato’s prisoners didn’t understand the powers behind the sun, just as we don’t understand the four-dimensional bulk universe. But at least they knew where to look for answers.”
Explore further: How much of the universe is black holes?
Journal reference: Nature
Provided by Perimeter Institute for Theoretical Physics

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(Phys.org) —Physicists Rodolfo Gambini and Jorge Pullin of University of the Republic in Montevideo, Uruguay, and Louisiana State University respectively, have applied the theory of Loop Quantum Gravity (LQG) to a simplified black hole. In so doing, as they describe in their paper published in the journal Physical Review Letters, they suggest that instead of a singularity existing at its center, there is a portal to another universe.
For many years theoretical physicists have believed that the universe came about as a result of a single Big Bang event—Einstein’s theories suggested it was so. The problem with this line of thinking however, is that the theory of general relativity can’t describe what came before the singularity, which should exist at the point in time just before the Big Bang. Theory also suggests that a similar singularity should exist at the center of black holes, but again, general relativity fails to describe them properly. Worse, there is the problem of the information loss paradox—if something falls into a black hole and is eventually squeezed to a singularity, what happens to the information it contained? Big Bang physicists can’t say.
To address these problems, Abhay Ashtekar and his team at Pennsylvania State University, back in 2006, came up with a theory known as loop quantum gravity. They suggested that instead of a singularity existing just before the Big Bang, there was the remains of a crunched down universe that had existed prior to the one that exists now. The universe didn’t just Big Bang itself into existence from nothing, they said, instead there is an infinite loop where a universe shrinks down to a very tiny spot, then explodes in a Big Bang, then shrinks down again, over and over again forever—hence the use of the term “loop” in the theory. Since that time, some in the field have begun to refer to the theory as the Big Bounce, to replace the name Big Bang.
In this new effort Gambini and Pullin applied LQG to a simplified model of a black hole. Their experiment showed that everything that was pulled into the black hole didn’t compress to a singularity after all—instead it was compressed to a certain small size, then was spit out in another part of the universe or into another universe entirely.
Because their model worked so well, the two suggest that it would likely work with real black holes as well. If this new theory is correct, they note, it would do away with the information loss paradox and open the door to the possibility of black holes being portals to other universes.
Explore further: Quantum shortcut could speed up many quantum technologies
More information: Loop Quantization of the Schwarzschild Black Hole, Phys. Rev. Lett. 110, 211301 (2013) prl.aps.org/abstract/PRL/v110/i21/e211301
Abstract
We quantize spherically symmetric vacuum gravity without gauge fixing the diffeomorphism constraint. Through a rescaling, we make the algebra of Hamiltonian constraints Abelian, and therefore the constraint algebra is a true Lie algebra. This allows the completion of the Dirac quantization procedure using loop quantum gravity techniques. We can construct explicitly the exact solutions of the physical Hilbert space annihilated by all constraints. New observables living in the bulk appear at the quantum level (analogous to spin in quantum mechanics) that are not present at the classical level and are associated with the discrete nature of the spin network states of loop quantum gravity. The resulting quantum space-times resolve the singularity present in the classical theory inside black holes.
via Synopsis
Journal reference: Physical Review Letters

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(Phys.org) —In publishing a story regarding work reported by Japanese physicists last month, Nature News has set off a bit of a tabloid firestorm by describing an obscure bit of physics theory as “the clearest evidence yet that our Universe could be just one big projection.” In two papers uploaded to the preprint server arXiv, Yoshifumi Hyakutake and colleagues from Ibaraki University in Japan offer evidence that supports a theory that suggests that a universe as we conceive of it could actually be a hologram of another two-dimensional space.
The papers follow up on a theory first proposed by Juan Maldacen, who in 1997, came up with what is now known as string theory, part of which suggests certain types of universes might actually be holograms of real two-dimensional universes, which is where, as he described it, “the real action would play out.”
String theory was widely embraced by the physics community because it did what no other theory could—provide a bridge across inconsistencies that arose between quantum physics and Einstein’s theory of relativity. The inconsistencies became apparent as physicists began contemplating black holes and their properties and found that the while quantum theory could explain what was observed, the theory of relativity could not. The only down side to string theory was that no one could come up with a proof of it. In this new effort, Hyakutake and his team appear to have come closer.
Hyakutake and various colleagues have been working on the problem for years, submitting papers as they go—all leading, apparently, to the two they’ve most recently uploaded. One of their papers describes mathematically what should happen, according to theory, in a black hole, with numbers that should describe its properties as well. The other describes what should result, theoretically speaking, if there were another, lower dimensional universe with no gravity. What’s surprising, of course, is that the two match, suggesting that one could be projecting the other as a hologram.
The papers don’t suggest that the universe we actually live in is a hologram, Hyakutake et al’s computations describe a universe with ten dimensions in the realm of the black hole and a single dimension universe when calculating characteristics of a gravity free two-dimensional universe. The work does provide a hint however, that what can be calculated using different dimensional universes could perhaps one day be calculated for our own. That of course would imply that what we see and do here might actually be occurring elsewhere and we are merely experiencing its holographic representation.
Explore further: Solving a fish mystery, with human implications
More information: Holographic description of quantum black hole on a computer, arXiv:1311.5607 [hep-th] arxiv.org/abs/1311.5607
Quantum Near Horizon Geometry of Black 0-Brane, arXiv:1311.7526 [hep-th] arxiv.org/abs/1311.7526

http://www.nature.com/news/simulations-back-up-theory-that-universe-is-a-hologram-1.14328

trophysicists duo propose Planck star as core of black holes
Feb 14, 2014 by Bob Yirka report
black holeEnlarge
This artist’s concept depicts a supermassive black hole at the center of a galaxy. The blue color here represents radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. Credit: NASA/JPL-Caltech
(Phys.org) —Two astrophysics, Carlo Rovelli and Francesca Vidotto, have uploaded a paper to the preprint server arXiv in which they suggest that a structure known as a Planck star exists at the center of black holes, rather than a singularity. This would suggest, they note, that black holes at some point return all the information they have pulled in, to the universe.
The current thinking regarding black holes is that they have two very simple parts, an event horizon and a singularity. Because a probe cannot be sent inside a black hole to see what is truly going on, researchers have to rely on theories. The singularity theory suffers from what has come to be known as the “information paradox”—black holes appear to destroy information, which would seem to violate the rules of general relativity, because they follow rules of quantum mechanics instead. This paradox has left deep thinking physicists such as Stephen Hawking uneasy—so much so that he and others have begun offering alternatives or amendments to existing theories. In this new effort, a pair of physicists suggest the idea of a Planck star.
The idea of a Planck star has its origins with an argument to the Big Bang theory—this other idea holds that when the inevitable Big Crunch comes, instead of forming a singularity, something just a little more tangible will result—something on the Planck scale. And when that happens, a bounce will occur, causing the universe to expand again, and then to collapse again and so on forever back and forth.
Rovelli and Vidotto wonder why this couldn’t be the case with black holes as well—instead of a singularity at its center, there could be a Planck structure—a star—which would allow for general relativity to come back into play. If this were the case, then a black hole could slowly over time lose mass due to Hawking Radiation—as the black hole contracted, the Planck star inside would grow bigger as information was absorbed. Eventually, the star would meet the event horizon and the black hole would dematerialize in an instant as all the information it had ever sucked in was cast out into the universe.
This new idea by Rovelli and Vidotto will undoubtedly undergo close scrutiny in the astrophysicist community likely culminating in debate amongst those who find the idea of a Planck star an answer to the information paradox and those who find the entire idea implausible.
Explore further: An improved model for star formation
More information: Planck stars, arXiv:1401.6562 [gr-qc] arxiv.org/abs/1401.6562

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