Big Bang Vs Inflationary Big Bang


by dm4b
Tags: bang, inflationary
dm4b
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#1
Dec7-12, 10:19 AM
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I was under the impression that originally the main impetus for inflationary Big Bang was that the original Big Bang model implied a finely tuned Universe, or highly unlikely starting conditions for the Universe.

In other words, the flatness and horizon problems, etc., don't necessarily indicate the original Big Bang has to be wrong. It just implies the Universe had to have a finely tuned beginning.

Well, perhaps the Universe really is fine tuned and our desire to avoid theories that seem to "predict" very unlikely starting conditions for the Universe has led us astray.

Since neither models go back to T=0, perhaps there was a mechanism that forced the Universe into what appears to be a finally tuned beginning. In other words, it isn't really a highly unlikely scenario - it only seems that way due to our lack of understanding of unknown physics that came into play at the very beginning.

So, I guess my questions is are there recent advances in cosmology that show additional advantages to the inflationary model and that exclude the original Big Bang model as impossible now.

Thanks.
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Nabeshin
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#2
Dec7-12, 01:14 PM
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Quote Quote by dm4b View Post
I was under the impression that originally the main impetus for inflationary Big Bang was that the original Big Bang model implied a finely tuned Universe, or highly unlikely starting conditions for the Universe.

In other words, the flatness and horizon problems, etc., don't necessarily indicate the original Big Bang has to be wrong. It just implies the Universe had to have a finely tuned beginning.

Well, perhaps the Universe really is fine tuned and our desire to avoid theories that seem to "predict" very unlikely starting conditions for the Universe has led us astray.

Since neither models go back to T=0, perhaps there was a mechanism that forced the Universe into what appears to be a finally tuned beginning. In other words, it isn't really a highly unlikely scenario - it only seems that way due to our lack of understanding of unknown physics that came into play at the very beginning.

So, I guess my questions is are there recent advances in cosmology that show additional advantages to the inflationary model and that exclude the original Big Bang model as impossible now.

Thanks.
The dynamical mechanism to explain the fine tuning is precisely inflation though! It does deal with physics beyond the standard big bang scenario, namely something weird happening around the GUT scale.
dm4b
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#3
Dec7-12, 04:39 PM
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Quote Quote by Nabeshin View Post
The dynamical mechanism to explain the fine tuning is precisely inflation though! It does deal with physics beyond the standard big bang scenario, namely something weird happening around the GUT scale.
I guess I was looking at that a bit differently.

For example, with the flatness problem you really do need fine tuning under the original Big Bang - specifically the Universe had to be very, very close to the critical density.

Under inflation, the observable Universe only appears flat in a way analogous to how the surface of the earth appears flat to us. So, really, it explains away any need for fine tuning, rather than being a mechanism for it.

Chronos
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Dec7-12, 11:29 PM
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Big Bang Vs Inflationary Big Bang


There was an interesting paper on initial conditions yesterday - Inflation as a Solution to the Early Universe Entropy Problem, http://arxiv.org/abs/1212.1087.
skydivephil
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#5
Dec8-12, 04:06 AM
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The fine tuning of Omega is definitely something resolved in inflationary big bang cosmology but not big bang (sans inflation) cosmology. But of course this isnt the only issue. Inflation solves the monopole problem, the horizon problem, the origin of structure problem and explains why the universe is so big and where the hot soup of particles comes from. So even if there was no observational evidence for inflation, which there is according to NASA WMAP team, then it would still have a lot going for it.
skydivephil
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#6
Dec8-12, 04:14 AM
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Quote Quote by Chronos View Post
There was an interesting paper on initial conditions yesterday - Inflation as a Solution to the Early Universe Entropy Problem, http://arxiv.org/abs/1212.1087.
Any comments on this paper? who think it'll satisfy the likes of Roger Penrose and Sean Caroll?


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