Questions tagged [observable-universe]
The observable universe of a given observer encompasses the volume of space from which information - particles, radiation - could ever (past, present or future) reach that observer.
239 questions
-1 votes
0 answers
63 views
Why I am not expanding? [duplicate]
We know universe is expanding and space is also expanding. When why we dont feel the space around us and ourself expanding or stretching .even an big object Does it negligible?
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1 vote
1 answer
96 views
Can a photon cross the visible horizon and come back if some galaxies across the visible horizon curved it's path significantly?
Can photons cross the visible horizon of the universe and the gravity of galaxies across the horizon make them come back to our side and would we be able to tell from their redshift?
user550784
0 votes
2 answers
382 views
Light travel distance and comoving distance in the Big Crunch scenario
I'm aware that the Big Crunch is practically ruled out, but I need it to ask my question. Imagine, that we live at the cosmic time of the reversal of the expansion, precisely when it stops. At the ...
user467398
1 vote
1 answer
145 views
How has the observable radius and mass within it varied over time?
How have the values for the radius of the observable universe and observable mass within this radius varied over the time of the universe? Was the observable radius bigger or smaller in the past? Was ...
2 votes
0 answers
145 views
Observable universe
What does observable universe mean? I saw your graphs in proper and comoving distances. An hypothetical object that emitted light at the Big Bang (after recombination: cosmological time $t=0$ and ...
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2 votes
1 answer
363 views
Negative Horizon distance
Consider a flat universe, here, proper distance can be given by R-W Metric: $$d_p (t_0) = c\int_{t_e}^{t_0}\frac{dt}{a(t)},$$ $t_e$ is the time when a photon is emitted from a distant galaxy, $t_0$ is ...
- 571
0 votes
1 answer
129 views
Horizon problem, what if our observable universe is roughly equal to the whole universe, especially in early times?
How do we know that at a time of 380.000 years, when CMB got free, the observable universe was not equal to the actual universe? Maybe they were roughly the same and couldn't that explain the horizon ...
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4 votes
3 answers
2k views
If the observable universe had only one galaxy, how would people know the expansion of the universe?
Hubble measured high redshifted galaxies to discover the cosmic expansion. In a hypothetical universe where only one galaxy exists, would there still be observational evidence for the Big Bang theory? ...
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