Big Bang Vs Inflationary Big Bang

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In summary, the paper discusses inflation as a solution to the early universe entropy problem. It supports the idea that inflation occurred and resolves many issues that were previously seen as problems with the big bang model. However, it is not the only solution and further research is needed to determine if inflation is the correct model.
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dm4b
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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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  • #2
dm4b said:
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.
 
  • #3
Nabeshin said:
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.
 
  • #4
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.
 
  • #5
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 isn't 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.
 
  • #6
Chronos said:
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?
 

1. What is the difference between the Big Bang theory and the Inflationary Big Bang theory?

The Big Bang theory states that the universe began as an extremely hot and dense singularity and has been expanding and cooling ever since. In contrast, the Inflationary Big Bang theory proposes that the universe underwent a rapid period of inflation, expanding exponentially in the first fraction of a second after the Big Bang. This theory helps to explain some of the observed features of the universe, such as its overall uniformity and the absence of magnetic monopoles.

2. How did the idea of inflation in the Big Bang theory come about?

The idea of inflation was first proposed by physicist Alan Guth in the early 1980s as a way to address some of the flaws in the original Big Bang theory. It was later refined by Andrei Linde and others, and has become a widely accepted explanation for the initial expansion of the universe.

3. What evidence supports the Inflationary Big Bang theory?

One of the main pieces of evidence for inflation is the observed uniformity of the cosmic microwave background radiation, which is the leftover heat from the early universe. This uniformity is difficult to explain without some sort of rapid expansion. Additionally, the theory has successfully predicted the distribution of matter in the universe on large scales and the existence of gravitational waves.

4. Are there any alternative theories to the Inflationary Big Bang?

Yes, there are alternative theories to the Inflationary Big Bang, such as the Steady State theory and the Cyclic model. However, these theories have not been as widely accepted and do not have as much evidence supporting them as the Inflationary Big Bang theory.

5. Can the Inflationary Big Bang theory be tested?

Yes, the Inflationary Big Bang theory can be tested through observations of the cosmic microwave background radiation and the distribution of matter in the universe. Additionally, experiments such as the BICEP2 and Planck missions have provided further evidence for the theory. However, as with any scientific theory, it is always subject to further testing and refinement.

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