All Questions
205
questions
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52
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Was "flow of time" equally fast during the life of universe? Is Doppler Effect the only interpretation of "shift to red"? [duplicate]
I'm an IT developer and recently I created a project where I tried to send signals between two threads in a slowing down environment. I simulated two points with their own clocks and tried to send a ...
- 101
2
votes
0
answers
76
views
An unusual calculation of our universe's age? [closed]
Does the following make sense? And has anyone else come
across this odd ~’cosmological coincidence’ before?…
…If we posit that our total universe mass is:
(1) $$M_{U}=\frac{{M_{pl}}^4}{{M_{p}}^...
- 149
4
votes
1
answer
675
views
Intuitive explanation of COSMIC TIME?
I came across the following statement, while studying a Newtonian model for cosmic expansion:
"If $R(t)$ is the scaling factor, we can define the Hubble parameter as $H(t)=\frac{\dot{R(t)}}{R(t)}...
- 152
2
votes
5
answers
503
views
What is the branch of physics that asks the question 'what was before the Big Bang'?
What is the branch of physics that asks the question 'what was before the Big Bang', assuming the Big Bang is truly what happened at the beginning of the universe? If there could be a better model ...
- 421
0
votes
0
answers
39
views
Planck time - what would I see? [duplicate]
Impossibly hypothetical, but to communicate the question: when the universe "ticks" a plank second, what does a particle do? I'd imagine the natural conception that it moves from position a ...
- 149
2
votes
1
answer
144
views
Common clock reference of Big Bang
Relativity tells us that there is no preferred reference frame, yet current cosmology does operate on the hypothesis that all points in the observable universe originate from the same big bang ...
- 4,892
1
vote
1
answer
95
views
What happens if we let time expand in the FLRW metric?
If we multiplied the time differential (dt) by a scale factor that depends on time in the FLRW metric, what would this imply on cosmology? In particular, what are its implications on the cosmological ...
- 468
0
votes
2
answers
119
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Time in the Standard Model of Cosmology
Beyond a formal preference for background independence, what is stopping us from setting cosmological time as a de facto universal timeline, analogous to newtonian absolute time? General relativity ...
- 1
0
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0
answers
23
views
Is the size/age of the universe dependent on your velocity? [duplicate]
As Photons do not experience time or space, then according to my thought experiment, all photons must occupy some kind of singularity as well as what WE observe from earth.
I was also thinking that ...
1
vote
1
answer
156
views
Why did the Big Bang happen first?
As far as I know, the laws of physics are time-reversal invariant, which means there is no preferred direction of time. The arrow of time emerges with entropy which is a property of macrostates, not ...
- 308
-6
votes
1
answer
97
views
What exists in the world according to the special relativity? [closed]
Before I learned about special relativity, I thought that only one 3-dimensional state of the world exists. Then, like in game of chess, in one "turn" previous state is destroyed - and the ...
9
votes
2
answers
1k
views
Has the age of the universe changed in 2023?
I teach high school physics and physical science. I was going through the definitions of theory and law when a couple of my students (of different periods) asked about some recent development that ...
- 203
0
votes
0
answers
47
views
Theoretical: what is the meaning of nothing? [duplicate]
Before the big bang, there was a point surrounded by nothing (no space or anything). Then the big bang happened and the universe expanded. so beyond the universe's limits, there is nothing? I don't ...
- 1
1
vote
2
answers
106
views
In spacetime time is a coordinate. Does it mean there is a single objective timeline for the Universe?
If every event can be defined with x, y, z, t coordinates - does it mean all events with the same t are composing the whole Universe at the moment t?
0
votes
1
answer
276
views
Is heat death absolutely and really inevitable? [duplicate]
As the second law of thermodynamics indicates, entropy would continue to grow in the universe until it reaches a maximal value (in an expanding universe with a cosmological constant, like ours) or ...
- 2,462