15 votes

Why do cosmologists assume that inflation began shortly after the Big Bang, rather than at the exact start?

The universe cannot have begun in an inflationary phase. Note that it is not necessarily the case that there was a phase that preceded inflation. However, if there was no phase preceding inflation, ...
Sten's user avatar
  • 4,654
5 votes

Energy density of the inflaton field

I wouldn't say obvious, especially to someone who isn't familiar with quantum field theory, but it's the type of expression that theorists write because it's the only possible thing it could be by ...
ScienceSnake's user avatar
  • 1,002
3 votes

If the energy density during inflation were lower, how would the CMB look in comparison to the observed CMB today?

We don't know the energy density during inflation. This should immediately tell you that it doesn't (directly) impact any of the observables that we are able to measure. Even though the inflation ...
Sten's user avatar
  • 4,654
1 vote

Are vacuum fluctuations that produce dark matter correlated to fluctuations that produce baryonic matter?

Yes. This question was only settled in the last decade or so, but initial variations in the baryon density and in the dark matter density seem to agree at the percent level. See for example "...
Sten's user avatar
  • 4,654

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