Symmetric big bang

[JonDE]

Is it possible that whatever cause the big bang to happen and make space expand also (for lack of a better phrase) tore time in two? Resulting in two universes moving in opposite directions of time, and could this be used to explain why there appears to be more matter then antimatter in the universe?

[Chalnoth]

Is it possible that whatever cause the big bang to happen and make space expand also (for lack of a better phrase) tore time in two? Resulting in two universes moving in opposite directions of time, and could this be used to explain why there appears to be more matter then antimatter in the universe?
Well, I'm not entirely sure this idea is coherent. The problem is that the description already assumes some sort of "super-time" under which this tearing of time in two could be observed. This kind of description, ultimately, does not work. Any description that is going to work has to operate as if the universe is all there is, and describe what goes on within it.

So if we instead describe what was going on within the universe, the picture you've drawn is one of a universe that, in the past, was collapsing and getting lower and lower in entropy (this is what is meant by having an opposite arrow of time), until it reached a turnaround point where it started to expand and increase in entropy. The difficulty here is that previous phase, where entropy was getting lower and lower, is tremendously unlikely. So much so that I would wager it makes the idea impossible.

And the problem with the matter thing is that as far as we know, matter simply didn't exist in the earliest parts of the universe when inflation was occurring. It was only later, when inflation ended that matter was generated. And when it was first produced it couldn't have been produced with anything resembling an asymmetry between matter and anti-matter: that asymmetry had to come about because of the detailed physics of what was going on in the massively hot furnace of our universe after the end of inflation.

[yenchin]

Certainly similar idea in the context of inflation has been entertained before (but I don't think it will help in explaining matter antimatter asymmetry because of what Chalnoth said in his last paragraph), see for example Spontaneous Inflation and the Origin of the Arrow of Time (http://arxiv.org/abs/hep-th/0410270) by Sean Carroll and Jennifer Chen:

Abstract: "We suggest that spontaneous eternal inflation can provide a natural explanation for the thermodynamic arrow of time, and discuss the underlying assumptions and consequences of this view. In the absence of inflation, we argue that systems coupled to gravity usually evolve asymptotically to the vacuum, which is the only natural state in a thermodynamic sense. In the presence of a small positive vacuum energy and an appropriate inflaton field, the de Sitter vacuum is unstable to the spontaneous onset of inflation at a higher energy scale. Starting from de Sitter, inflation can increase the total entropy of the universe without bound, creating universes similar to ours in the process. An important consequence of this picture is that inflation occurs asymptotically both forwards and backwards in time, implying a universe that is (statistically) time-symmetric on ultra-large scales."

[Chalnoth]

Certainly similar idea in the context of inflation has been entertained before (but I don't think it will help in explaining matter antimatter asymmetry because of what Chalnoth said in his last paragraph), see for example Spontaneous Inflation and the Origin of the Arrow of Time (http://arxiv.org/abs/hep-th/0410270) by Sean Carroll and Jennifer Chen:

Abstract: "We suggest that spontaneous eternal inflation can provide a natural explanation for the thermodynamic arrow of time, and discuss the underlying assumptions and consequences of this view. In the absence of inflation, we argue that systems coupled to gravity usually evolve asymptotically to the vacuum, which is the only natural state in a thermodynamic sense. In the presence of a small positive vacuum energy and an appropriate inflaton field, the de Sitter vacuum is unstable to the spontaneous onset of inflation at a higher energy scale. Starting from de Sitter, inflation can increase the total entropy of the universe without bound, creating universes similar to ours in the process. An important consequence of this picture is that inflation occurs asymptotically both forwards and backwards in time, implying a universe that is (statistically) time-symmetric on ultra-large scales."
I really like that idea put forth by Sean Carroll and Jennifer Chen. Others have presented similar ideas. But I should mention that it is fundamentally different from the original post in that it is asymmetrical: you have an initial fluctuation into a low-entropy state, and the configuration of that state determines the direction of time as seen within the fluctuation.

[qraal]

Years ago there was a theory of the Big Bang in which four Universes had their common origin - one of matter, one of antimatter and two tachyon Universes. I wish I could remember the cosmologists who proposed it. Bob Shaw used it in his "Orbitsville" trilogy, but it was a legit cosmological theory.

[qraal]

Years ago there was a theory of the Big Bang in which four Universes had their common origin - one of matter, one of antimatter and two tachyon Universes. I wish I could remember the cosmologists who proposed it. Bob Shaw used it in his "Orbitsville" trilogy, but it was a legit cosmological theory.

Found it. J.Richard Gott III proposed it in 1973...

A Time-Symmetric Matter, Antimatter, Tachyon Cosmology (http://adsabs.harvard.edu/full/1974ApJ...187....1G)

...what I misremembered as two tachyon universes is just one, from the Space-Time diagram of the whole.

[yenchin]

Somewhat related: http://www.physorg.com/news/2011-07-big-quick-conversion-antimatter.html

Arxiv: http://arxiv.org/abs/1106.1260

[bcrowell]

Is it possible that whatever cause the big bang to happen and make space expand also (for lack of a better phrase) tore time in two? Resulting in two universes moving in opposite directions of time, and could this be used to explain why there appears to be more matter then antimatter in the universe?

If this was going to mean anything, you would have to define what you meant by your terms: "tore time in two," "moving in opposite directions of time."

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[qraal]

Somewhat related: http://www.physorg.com/news/2011-07-big-quick-conversion-antimatter.html

Arxiv: http://arxiv.org/abs/1106.1260

Fascinating model. I am still trying to understand the proposed mechanism for changing the parity of matter in the Big Bounce. Such cosmological models do kind of make existence seem pointless for Life, since there's no evident survivals of intelligence from one cosmic epoch to the next.