No, but there’s a penguin on the telly.
Posted on 02/09/2015 10:55:17 AM PST by Red Badger
(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
I don’t know, but i ‘ad an awful hard time burying the cat.
Not quite...but he’s not at all well.
Maybe it’s not a good analogy, but when you blow up a balloon (imagined as a miniature big-bang type universe) the expanding balloon does not create space, it occupies previously-existing space. So an expanding universe must be moving into SOMETHING when it expands. As the Unfrozen Caveman Lawyer used to say on SNL, “My primitive mind cannot grasp these concepts.”
This isn’t a new idea. I’ve never liked the explanation of redshift. Here is another older link. The first time I read about this was in the late 80s early 90s.
http://www.nature.com/news/cosmologist-claims-universe-may-not-be-expanding-1.13379
My hat’s off to the Designer.
Or they're not really moving away from each other, and there isn't really any expansion.
Well, yes and no.
I am relieved. All is right with the Universe.
Um, until these calculators can start with the first expression of space and the first expression of time (point/moment) their calculations will spit out ONLY what they are inputting for potentials.
I hair you talkin’.
No, but there’s a penguin on the telly.
http://www.nature.com/news/cosmologist-claims-universe-may-not-be-expanding-1.13379
hehehe
so cute! :-)
Fred Hoyle coined the term ‘Big Bang’.....................
I have never heard anyone explain how the “stuff” that made up the singularity got there.
me neither! LOL!
That’s just baseless speculation. If there is something outside the universe, we cannot observe it, so it’s outside the realm of science to even think about.
Depsite the “aether drag” experiments coming up negative, it has always seemed to me that there must be a medium of some kind out there, and I think that science continually predicts it.
For example, how are gravitational waves propagated if not through a medium? In this case, the medium is “space-time” itself, supposedly. Now space itself seems an odd medium, but if it can propagate waves, then what else can you call it? If space is a medium, and by definition, space fills all of space, then is that not a kind of “aether”?
How about vacuum fluctuations? What exactly is fluctuating if nothing is there? It seems if something is fluctuating, there must be a “something” to fluctuate, hence a medium.
Then there is the “cosmic microwave background radiation”, which is distributed throughout space. Relativity tells us that matter and energy are interchangeable, so why does a medium only have to be composed of matter? Wouldn’t a distribution of energy throughout the universe itself qualify as a medium?
Or how about gravity itself? If space is a true vacuum, a true nothing, then there's nothing for gravity to bend, yet gravitational bending of light is observed. There is clearly a medium in which light propagates. The warp and woof of it is observed, and yet has been denied. You can't bending "nothing", ergo: there is something. Call it aether, call it quantum sludge, but if it walks like a duck and it quacks like a duck, well, the scientists don't have to call it a duck if egos won't permit, but the existence of the water fowl cannot be denied.
“If space is a true vacuum, a true nothing, then there’s nothing for gravity to bend, yet gravitational bending of light is observed. There is clearly a medium in which light propagates. The warp and woof of it is observed, and yet has been denied. You can’t bending “nothing”, ergo: there is something.”
True, except that space isn’t being bent in relativity, “space-time” is, which is a subtle distinction but it has important implications. So, perhaps this “space-time” itself is the replacement aether needed, at least to make relativity function.
On the other hand, I still doubt Einstein’s explanation that space-time warping is the cause of gravity. If you think about the classic demonstration of it (the rubber sheet and bowling ball one), it actually demonstrates nothing. For, if you did the experiment in an environment where there was no pre-existing gravity well to pull down the bowling ball, then no motion would be observed. So it’s just a clever magic trick, and not a demonstration of the principle.
It seems to me that mass warping space-time can explain light difraction very obviously, but how it would cause gravity remains a mystery.
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