All Questions
132
questions
7
votes
3
answers
5k
views
If we consider the spacetime of the universe to be four-dimensional, does the Big Bang lie in its center?
Apologies for the (hopefully now somewhat less) clickbait-y title. Now, of course, I know that the Big Bang did not happen at any point connected to a single point in our current $3$-dimensional ...
- 1,897
0
votes
0
answers
100
views
Movement of galaxies vs expansion of space
I can readily accept the theory that the universe is expanding as a mathematical model to explain the fact that all galaxies are moving away from each other, but I have difficulty understanding ...
- 1
3
votes
4
answers
3k
views
Is the universe really a closed physical system? [closed]
It is assumed in most physics discussions that the universe is a closed physical system. But is it really? I am defining the universe as the entirety of everything physical, not merely the observable ...
- 1,252
2
votes
5
answers
1k
views
Why is it that the further a galaxy is, the greater is its recessional velocity?
The exam question is:
Explain how red-shift provides evidence for the Big Bang theory.
One of the points in the answer is:
the further away the galaxy is, the greater is their recessional speed
...
- 21
2
votes
0
answers
58
views
Space expansion or generation [duplicate]
When physicists assert that space is expanding, does this imply the creation of new space? If so, why do they use the term "expansion" instead of "generation"?
- 31
0
votes
0
answers
26
views
What is the expansion of space of one megaparsec in one year?
suppose we know Hubble's constant. In a hypothetical scenario an astronomer finds and confirms Hubble's law for a galaxy 1 mega parsec away.
Next year, how much distance will the hypothetical ...
1
vote
1
answer
67
views
Does the universe have an infinite volume? [duplicate]
The implications of a spatially infinite universe is profound, but so are the implications of a finite universe. What we know about this issue?
- 11
0
votes
2
answers
47
views
Is this the Format of the Observable Universe?
The way I have it is: the Observable Universe looks as follows. In some ball, all the galaxy clusters exist, then in a bigger concentric ball the dark ages exist (no galaxies), then on the surface of ...
- 61
0
votes
1
answer
122
views
Cosmological principle: can there be a center of the universe "outside" the universe?
I've been watching youtube videos about the cosmological principle. I understand that the expansion of the universe is not concentric (around a specific point in space). The balloon example helped me ...
- 3
-1
votes
2
answers
74
views
The speed of expansion of space in big freeze
In the case of big freeze, space expansion will be accelerating and there appears to be a lot of different phenomena occurring. However, in the case of big rip, the expansion is super-accelerating so ...
- 13
4
votes
2
answers
950
views
Could it be possible that the Universe is expanding in some areas while contracting in other areas?
I am wondering if could it be possible that the Universe is expanding in some areas while contracting in other areas.
I have wondered if perhaps as one area of the Universe is squeezed inward by some ...
- 478
2
votes
1
answer
171
views
Particle horizon in an empty universe
So in this thread,
Can space expand with unlimited speed?,
the author Pulsar made amazing diagrams of different horizons and paths for a benchmark model that describes our current universe, and gave a ...
- 161
4
votes
3
answers
2k
views
Will a light come back within finite years?
In this answer Javier said
Imagine the universe was the inside of a ball. We're 3D now, so no one is hiding any dimensions. This ball has a border, except it's not really a border. You should think ...
- 405
0
votes
2
answers
91
views
What is there at a point the universe hasn't expanded past yet? [duplicate]
(Please don't mark as a duplicate)
If the universe is constantly expanding that means that there is a point the univese hasn't expanded past, with that what would be past that point? This isn't about ...
- 11
2
votes
2
answers
178
views
Space-time continuum expansion
I still don't understand how the expansion of the universe works.
If the universe is made up of an infinite number of points that make up space-time, then how can space expand or stretch. Common sense ...
- 343