Astrophysicists propose new twist on Big Bang

84 点作者 blazar将近 11 年前

7 条评论

trhway将近 11 年前

>The researchers emphasize that this idea, though it may sound absurd, is grounded firmly in the mathematics describing space and time. Specifically they’ve used the tools of holography to “turn the big bang into a cosmic mirage.”embedding into higher dimension spaces (or in general - into more "richer" structures) is a convenient mathematical tool and it works nice ... in mathematics. To work in physics that higher dimension space must really exist. Otherwsie, for all we know, out Universe can be just a 3d surface of a 4d nut that a small 4d squirrel puppy is about to bite into.

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adinb将近 11 年前

Original paper title: Out of the White Hole: A Holographic Origin for the Big BangArxive page (w/abstract): <a href="http://arxiv.org/abs/1309.1487" rel="nofollow">http://arxiv.org/abs/1309.1487</a>Direct link to paper: <a href="http://arxiv.org/pdf/1309.1487v2" rel="nofollow">http://arxiv.org/pdf/1309.1487v2</a>

biot将近 11 年前

This isn't a particularly new twist. The idea of our universe coming from a black hole has been around for quite some time, as this 1998 article discusses:<a href="http://martinelli.org/rexpansion/bhole.htm" rel="nofollow">http://martinelli.org/rexpansion/bhole.htm</a><pre><code> "if we run time forwards, we can kind of visualize the beginning of our universe as a very rapid collapse (the inverse of "Inflation"). A similar kind of event happens when a star (hot, spherical, massive, dense...) becomes so dense and massive it collapses in on itself and forms that mysterious black hole. Here's an interesting question to explore... "Did our universe begin as a star that underwent a gravitational collapse?" I.e., do we live in a black hole?" </code></pre> Perhaps the novelty is a formal theory around the idea?

GorgeRonde将近 11 年前

This tends to confirm Lee Smolin's embryo-theory of cosmological natural selection.Source : <a href="http://en.m.wikipedia.org/wiki/Cosmological_natural_selection#Cosmological_natural_selection" rel="nofollow">http://en.m.wikipedia.org/wiki/Cosmological_natural_selectio...</a>Cosmological natural selection Smolin's hypothesis of cosmological natural selection, also called the fecund universes theory, suggests that a process analogous to biological natural selection applies at the grandest of scales. Smolin published the idea in 1992 and summarized it in a book aimed at a lay audience called The Life of the Cosmos.The theory surmises that a collapsing[clarification needed] black hole causes the emergence of a new universe on the "other side", whose fundamental constant parameters (masses of elementary particles, Planck constant, elementary charge, and so forth) may differ slightly from those of the universe where the black hole collapsed. Each universe thus gives rise to as many new universes as it has black holes. The theory contains the evolutionary ideas of "reproduction" and "mutation" of universes, and so is formally analogous to models of population biology.The resulting population of universes can be represented as a distribution of a landscape of parameters where the height of the landscape is proportional to the numbers of black holes that a universe with those parameters will have. Applying reasoning borrowed from the study of fitness landscapes in population biology, one can conclude that the population is dominated by universes whose parameters drive the production of black holes to a local peak in the landscape. This was the first use of the notion of a landscape of parameters in physics.Leonard Susskind, who later promoted a similar string theory landscape, stated:"I'm not sure why Smolin's idea didn't attract much attention. I actually think it deserved far more than it got."

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joe_the_user将近 11 年前

OK,The thing about this popular article is it seems to imply that the universe coming out of a black hole is different from it coming out from any kind of singularity.Well, reading the real article, it seems this popular article got things garbled. The main problem they seem raise with the big bang is that it is a "naked" singularity - there's no barrier between the world and the singular point. So what they are doing is looking at a higher dimensional black hole and finding a non-naked singularity that would generate approximately the same effects as the big bang. There is still a singularity at work here, it is simply that the singularity is not directly spewing matter out. "No naked singularities" is a general principle I recall from scanning general relativity articles.

thisjepisje将近 11 年前

So how did this 4d universe come about? :D

calhoun137将近 11 年前

I think this idea is almost certainly false, and it has it's genesis from a mostly discredited psuedo-physics theory called the holographic universe[1]. But at least there is a testable prediction! In my opinion, the fact that they offer a testable prediction merits a more thorough consideration of the claims.First of all, it has been well understood for multiple decades that the General Relativity(GR) breaks down, and is no longer true, at mass/energy scales that are present inside of a black hole. This is known because physical quantities must be finite, but GR predicts the strength of a gravitational field inside of a black hole is infinite. If string theory is true (and I don't believe it is), then this would be a valid situation to apply it to, since we know that there is unknown physics at play inside of a black hole.Furthermore, the standard big bang cosmology is based on the idea that the beginning of time is a "black hole in time", in the sense that as t->0, the strength of the gravitational field diverges to infinity. Thus, it has been well known for decades that GR is not a valid physical theory at very short time scales after the beginning of time (this would be the epoch of inflation[3]).It is perhaps not apparent to the casual observer that this paper is based on a very bizarre sect within string theory, known as the "Holographic Universe", which according to Wikipedia "suggests that the entire universe can be seen as a two-dimensional information structure "painted" on the cosmological horizon". This is just a bunch of fancy words designed to blow smoke in your eyes, and the entire theory is sort of a joke as far as most physicists I know are concerned.There are actually a number of strange cults within string theory, another one that is good for a laugh is the Anthropic Princple[4]. This theory claims that even though the 11 dimensional D-Brane that is folded into a Calubi-Yau manifold upon which string theory is based predicts trillions of possible universes, the universe we live in exists because it is the only possible one we could live in:"the conditions happen to be just right for the existence of (intelligent) life on the earth at the present time. For if they were not just right, then we should not have found ourselves to be here now, but somewhere else, at some other appropriate time."This kind of nonsense is why I left research in theoretical physics to purse computer science and programming, which truly is the cutting edge of science. There is a lot of valuable physics research going on in material science departments(for example), but the string theory department needs to constantly justify their funding by making extremely bold claims such as "what we perceive as the Big Bang could be the three-dimensional “mirage” of a collapsing star in a universe profoundly different than our own".[1] <a href="http://en.wikipedia.org/wiki/Holographic_principle" rel="nofollow">http://en.wikipedia.org/wiki/Holographic_principle</a>[2] <a href="http://en.wikipedia.org/wiki/D-brane" rel="nofollow">http://en.wikipedia.org/wiki/D-brane</a>[3] <a href="http://en.wikipedia.org/wiki/Inflation_(cosmology)" rel="nofollow">http://en.wikipedia.org/wiki/Inflation_(cosmology)</a>[4] <a href="http://en.wikipedia.org/wiki/Anthropic_principle" rel="nofollow">http://en.wikipedia.org/wiki/Anthropic_principle</a>