Cosmological inflation refers to an era of expansion that lasted for approximately $10^{-34}$ seconds, during which the universe expanded by a factor of approximately $10^{26}$ in every direction. This is different from ordinary space expansion and from the acceleration in expansion we experience now and questions tagged by inflation should pertain to this era and not be about the expansion of the universe in general.
Questions tagged [cosmological-inflation]
751 questions
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What was the major discovery on gravitational waves made March 17th, 2014, in the BICEP2 experiment?
The Harvard-Smithsonian Centre for Astrophysics held a press conference today to announce a major discovery relating to gravitational waves. What was their announcement, and what are the implications?
Would this discovery be confirmation of…
Physics_maths
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8 answers
Is the Big Bang defined as before or after Inflation?
Is the Big Bang defined as before or after Inflation? Seems like a simple enough question to answer right? And if just yesterday I were to encounter this, I'd have given a definite answer. But I've been doing some reading while writing up my thesis…
Jim
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If string theory is inconsistent with observations, why hasn't it been rejected yet?
I'm no expert on string theory, but I've been reading about it. I've been quite surprised because of how it appears to be inconsistent with observations, but hasn't been rejected yet. Examples:
On the cosmological implications of the string…
Allure
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27
votes
5 answers
Size of universe after inflation?
Wikipedia states the period of inflation was from $10^{-36}$sec to around $10^{-33}$sec or $10^{-32}$sec after Big Bang, but it doesn't say what the size of the universe was when inflation ended. Just saw a Brian Greene show on the Multiverse and I…
Art Hays
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Photons in expanding space: how is energy conserved?
If a photon (wave package) redshifts (stretches) travelling in our expanding universe, is its energy reduced?
If so, where does that energy go?
IljaBek
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Before inflation, what sets the initial value of the inflaton field?
[This is a version of the question that I've revised based on helpful comments from Dan.]
I haven't studied inflation at a technical level. My picture of the process is that we have an inflaton field $\phi$ which is a scalar and has a potential…
user4552
19
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4 answers
Could quantum fluctuations spawn real matter?
Would it be plausible for fluctuations in the QED vacuum to spawn actual matter (such as quarks, electrons the constituents of a hydrgen atom) given enough time and space?
Justin
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Inflation and the Meaning of Time
I'm not quite sure how to ask this so that it can be answered in layman's terms, but I have lately seen, in several places, that with cosmological inflation, there was a point where the universe expanded faster than the speed of light.
In this…
Jim
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18
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4 answers
Will the Big Rip tear black holes apart?
There seems to be an obvious contradiction between the predictions of the physics of black holes and the Big Rip, a predicted event about 16.7 Gyr in the future where local groups, galaxies, solar systems, planets, and even atoms will be torn apart.…
Alan Rominger
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How does Inflation solve the Magnetic Monopole problem?
Cosmological Inflation was proposed by Alan Guth to explain the flatness problem, the horizon problem and the magnetic monopole problem. I think I pretty much understand the first two, however I don't quite understand how a period of exponential…
Benjamin Horowitz
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Can the Big Rip really rip apart an atomic nucleus?
Some scenarios describing the fate of the matter vs dark energy tug of war on the universe involve the acceleration of the universe increasing to the point that it ends up ripping apart even atoms. This is called the Big Rip.
This makes no sense to…
John
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Time diffeomorphisms breaking in inflation
I am currently working on the topic of inflation.
It seems that at the stage of inflation, the universe can be described as a de Sitter space. In such a space, all spacetime diffeomorphisms are preserved. (That is something I don't really understand…
AnSy
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How is it possible the universe expanded faster than the speed of light during inflation?
In a documentary written in collaboration with Stephen Hawking, the narrator (supposedly Stephen Hawkings) says that by the time the cosmos was 10 minutes old, it had already expanded thousands of light years in diameter. How is it possible that…
Lisa Jacobs
14
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1 answer
On Flatness problem, Inflation etc
I have a couple of naive questions from the topic of the title.
We know
\begin{eqnarray}
\Omega-1=\frac{k}{a^2H^2}-\frac{\Lambda}{3H^2}
\end{eqnarray}
Now I read that from the standard big bang (SBB) model $\frac{1}{aH}$ increases with time and in…
user1349
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7 answers
How does the whole universe agree on the laws of physics?
How is it possible that the every particle in the universe agrees on the laws of physics?
Note that I'm not asking 'why', I'm asking 'how'.
I might ask, "How does my water behave the same as your water?", and a reasonable answer could be: "By being…
Rocketmagnet
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