All Questions
Tagged with big-bang-theory cosmology
38
questions
4
votes
0
answers
101
views
From what distances do the atoms in you come from?
If the atoms of a human come from stars, comets, nebulas and magnetrons, then what is the greatest distance that two atoms of a human can possibly have been away from each other previously? Perhaps ...
- 4,268
3
votes
1
answer
180
views
Question on the singularity theorem
I have just started studying Cosmology and we have been asked to prove that in an expanding FRW Universe which obeys the strong energy condition: $$\rho + 3P >0$$
Then there must exist a Big Bang ...
- 61
2
votes
1
answer
854
views
What is the 'scale factor' equation for a dark-matter dominated universe?
The Friedmann equations can be solved exactly in presence of a perfect fluid with equation of state
$${\displaystyle p=w\rho c^{2}} \qquad p=w\rho c^2$$
where ${\displaystyle p}$ is the pressure, ${\...
- 5,307
1
vote
2
answers
290
views
Why can't we point the centre of the universe from inflation graph we see?
This question is not about whether it makes sense to have a centre of the universe or not instead, it's about the inflation graph we used to see while describing the Big Bang. From the inflation graph ...
- 1,007
4
votes
1
answer
731
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What happened before, Big Bang or inflation?
I always thought that the cosmic inflation happened after the big bang (10-36 sec) and lasted for a very tiny fraction of time).
Now, I recently came across a couple of articles (links below) claiming ...
- 91
5
votes
0
answers
126
views
Does the cosmological principle apply to the entire universe?
Some cosmological models assume that the universe is isotropic and homogeneous and that is also flat and infinite. If the universe is infinite now it was infinite immediately after the big bang. If ...
- 91
-3
votes
1
answer
297
views
Is our universe a singularity?
According to the Big Bang theory our universe used to be a lot smaller in size.
It actually used to be so small that in the beginning it used to be a singularity.
And the universe started to expand ...
- 1
2
votes
1
answer
186
views
Did Einstein supported Big Bang Theory cosmological model?
Einstein made many predictions, including gravitational waves and the possibility of black holes.
Relativity is taken into consideration for the Big Bang model, so did Einstein agree with it or did ...
- 341
1
vote
1
answer
208
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What reference frame do age-of-the-universe calculations assume?
I'm thinking, in particular, about general relativity. When we speak, for example, of neutrino decoupling, what do we mean when we say this happened in the first second after the Big Bang? Do we mean ...
- 163
8
votes
1
answer
256
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How do we know so many details about Big Bang, but we do not know if Universe is finite/infinite?
I understand that this question may be too vague, but I am confused about the following:
On one hand we know a lot of "details" about Big Bang, like really precise details, evolution of universe, age ...
- 181
1
vote
1
answer
201
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Is it possible that the Universe is expanding due to additional Big Bang events?
Is it theoretically possible that the Universe is expanding due to additional Big Bang events that have occurred at the same location that the original Big Bang occurred at?
Perhaps there has been an ...
user23327
0
votes
1
answer
144
views
Fundamental axioms in LCDM
What are the axioms (if any) behind the LCDM model of cosmology?
NB: axioms, not postulates (e.g., inflation)
user19333
2
votes
0
answers
54
views
How the observed deuterium abundance constrains big bang nucleosynthesis?
I know deuterium can be used as a good tracer to constrain the big bang nucleosynthesis. But can anyone tell me the in details how this is actually done?
- 187
2
votes
1
answer
368
views
How does inflation justify the nonexistence of magnetic monopoles?
It is said that inflation justifies that magnetic monopoles don't exist. Can anyone explain how inflation theory explains the non existence of magnetic monopoles?
- 529
9
votes
2
answers
208
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How Good Are the Upper Limits on Heavy Elements?
There are between 90 and 254 stable nuclei all the way up to element number 82. In discussions and graphs about big bang nucleosynthesis nothing above lithium is even mentioned. It's a pretty safe bet ...
- 2,946