All Questions
85
questions
1
vote
2
answers
530
views
Please help me with this paradox [closed]
Physicists believe that some galaxies are moving away from us at faster than the speed of light. A galaxy that is moving away from us at faster than the speed of light would be moving backwards in ...
- 53
1
vote
3
answers
86
views
Does the fact that we are able to see CMBR implies that universe expanded faster than light?
Supposedly, the universe underwent rapid expansion immediately after the big bang, surpassing the speed of light. If we can detect remnants from that era, does this suggest they moved faster than ...
- 21
1
vote
2
answers
470
views
Isn't the universe older than 13.8 billion years? [duplicate]
To preface this, I'm not an expert, I'm just an avid astronomer with little mathematical knowledge.
I was watching a video that was explaining the cosmic scale and how the observable universe is only ...
- 299
9
votes
2
answers
4k
views
Why do we need inflation?
wiki (https://en.wikipedia.org/wiki/Inflation_(cosmology)) says that immediately after BB there was expansion at speed greater than $c$, what makes this necessary, what would happen if expansion took ...
user337596
2
votes
2
answers
133
views
If galaxies beyond the cosmological event horizon move faster than light is then that motion a combination of their KE and space expansion?
If galaxies beyond the cosmological event horizon move faster than light is then that motion a combination of their KE and space expansion? Their KE alone isn't enough for them to move faster than ...
- 2,255
3
votes
1
answer
334
views
Can we observe the universe expanding faster than light?
I am looking at the sky, and I see two objects moving away from each other with speed greater than the speed of light.
Light from one object is not fast enough to reach the other. So I decided to help ...
- 2,127
0
votes
2
answers
122
views
Is there empirical evidence supporting a universe expanding faster than light?
We receive no light from galaxies beyond the cosmological horizon, but if they were moving away only at light speed, it seems to me their light wouldn't reach us. Is there any observations or ...
- 93
10
votes
7
answers
5k
views
Why is FTL travel impossible if the universe expands FTL?
If the universe is expanding spacetime faster than light (FTL), is FTL travel no longer completely impossible?
Do not care about energy requirements or needing new tech, just if it is NOT physically ...
- 141
3
votes
2
answers
130
views
Faster-than-light gravitational waves and faster-than-light expansion in the inflation
I have no introduction to the inflationary epoch. I know, however, that during this time space-time expanded with a speed faster than the speed of light. If gravitational waves are perturbations of ...
- 585
0
votes
0
answers
33
views
Questions on observations of faster than light recession of galaxies [duplicate]
I've been reading several threads here and online articles trying to absorb the current understanding of observations of far galaxies receding faster than the speed of light, it is said because the ...
- 1
-1
votes
1
answer
53
views
Big Bang and relativity [duplicate]
Wasn't the big bang's explosion itself faster than speed of light? how does this not violate relativity, I had read an explanation earlier but it wasn't sufficient, can someone explain to me how the ...
3
votes
2
answers
273
views
How can spacetime be expanding faster than the speed of light? [duplicate]
How can spacetime be expanding faster than the speed of light when the speed of light is the speed limit of the universe?
- 117
2
votes
1
answer
82
views
Can we observe an event that occurs more than 13.7 billion light years away? [duplicate]
In Kurzgesagt's latest video about the largest black holes, the narrator says that two black holes have been observed orbiting each other at a distance of 17 billion light years from Earth. So light ...
- 437
1
vote
1
answer
178
views
When do special relativity causally linked reference frames split into general relativity un-linked?
I'm looking for the "a-ha" moment in trying to understand how the super-luminal apparent speeds of the universe inflation theory are allowed.
Specifically, the short explanation is that &...
- 113
2
votes
0
answers
68
views
What would happen if universe wouldn’t accelerate faster than speed of light? [closed]
Its quite stunning to assume that not only space-time is expanding but also the rate of expansion is greather that speed of light.
But after the initial surprise, I ve been wondering if that fenomena ...
- 21