Cosmological Inflation: Theory and Observations

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The discussion centers on a review paper by Daniel Baumann and Hiranya V. Peiris that explores cosmological inflation and its connection between quantum mechanics and cosmic observations. The authors explain how quantum fluctuations during inflation lead to macroscopic density variations observable in the cosmic microwave background (CMB). Key topics include the implications of inflation for understanding the early universe and the potential for tracing its history through CMB anisotropies. Participants express curiosity about the paper's stance on eternal inflation and the origins of perturbations that drive inflation. Overall, the paper is recognized for its mainstream perspective on inflationary theory and its observational support.
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arXiv:0810.3022 [pdf, other]
Title: Cosmological Inflation: Theory and Observations
Authors: Daniel Baumann (Harvard), Hiranya V. Peiris (Cambridge)
Comments: 18 pages, 12 figures. Invited review to appear in Advanced Science Letters Special Issue on Quantum Gravity, Cosmology and Black Holes
Subjects: Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
In this article we review the theory of cosmological inflation with a particular focus on the beautiful connection it provides between the physics of the very small and observations of the very large. We explain how quantum mechanical fluctuations during the inflationary era become macroscopic density fluctuations which leave distinct imprints in the cosmic microwave background (CMB). We describe the physics of anisotropies in the CMB temperature and polarization and discuss how CMB observations can be used to probe the primordial universe.
 
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Is this paper theorizing or eleborating on some form of eternal inflation? Or is there some consideration of the possibility that entropy can be reversed in parches? Does it suggest that there can be tracing of inflation's history or is the history lost in a maze of fluctuating rates and patches of inflation, but all in the direction of final entropy?
 
Force1 said:
Is this paper theorizing or eleborating on some form of eternal inflation? Or is there some consideration of the possibility that entropy can be reversed in parches? Does it suggest that there can be tracing of inflation's history or is the history lost in a maze of fluctuating rates and patches of inflation, but all in the direction of final entropy?

To me it suggests one should play with some numbers ( numbers from the washing machine),
And come up with a macrscopic white wash, nice, so long as there is not too much starch.
 
Lol, that doesn't seem like an endorsement. Where do you stand?
 
Inflation is a convergent theory - i.e., is supported by multiple, unrelated observations. But, like most other cosmological theories, it can only take you back so far into the early universe.
 
Yes. But there is Big Bang Theory with inflation and there is eternal inflation :), the arrow of time, etc. In the OP, the abstract mentions, "a particular focus on the beautiful connection it provides between the physics of the very small and observations of the very large". Does it suggest that the micro world and the macro world have similarities in how they function only on vastly different scales? If so I would be interested in that full text. Is there a PDF file availavble?
 
Force1 said:
Yes. But there is Big Bang Theory with inflation and there is eternal inflation :), the arrow of time, etc. In the OP, the abstract mentions, "a particular focus on the beautiful connection it provides between the physics of the very small and observations of the very large". Does it suggest that the micro world and the macro world have similarities in how they function only on vastly different scales? If so I would be interested in that full text. Is there a PDF file availavble?

The paper is, presumably (I've only read the abstract) discussing how quantum mechanical early time perturbations in the scalar field driving inflation produce macroscopic density fluctuations imprinted on the CMB.

The pdf is available here: http://arxiv.org/abs/0810.3022
 
cristo said:
The paper is, presumably (I've only read the abstract) discussing how quantum mechanical early time perturbations in the scalar field driving inflation produce macroscopic density fluctuations imprinted on the CMB.

The pdf is available here: http://arxiv.org/abs/0810.3022
Thank you. Now that I read the abstract again I see that you are right.

It would be interesting to know if paper takes a position on the cause of the initial expansion and inflation or at least what lead to the perturbations? It seems clear that the anisotropy would require perturbations and the large scale of the anisotropy would point to them early during inflation.
 
It does take a position on the post big bang universe, it does not posit any precursor conditions - which is very mainstream.
 
  • #10
Yes, it is very mainstream. But in my minds ear I can hear Daniel Baumann (Harvard), and Hiranya V. Peiris (Cambridge) talking by satellite phone and Dan saying, "Hey Hirny, don't you think we should mention that the infinitesimal perturbations came from preconditions? And Hirny saying, "Shut your mouth, fool" :).
 
  • #11
I think not, but that is merely an opinion.
 

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