All Questions
209 questions
1vote
1answer
87views
Conformal time values at important epochs in the history of the universe
Neglecting the effect of dark energy for the late time evolution of the universe, one can correlate the coordinate time with temperature in RD and MD epochs RD ($10^{-6}MeV < T < 10^{16}MeV$) ...
- 3,374
-6votes
2answers
198views
How total mass of universe is calculated? [closed]
I think that Total mass of universe can be calculated using below formula. Total mass of universe = (Age of Universe) × (Planck mass / Planck time) = (4.35×10^17 ) × (2.18×10 ^−8 / 5.39×10^−44 ) Kg = ...
0votes
0answers
65views
Time-temperature relation in matter dominated and dark energy dominated era
Can we derive a cosmological relation between time and temperature in matter dominated era and in dark energy era? Something like the radiation era expression here $$T= \frac{t^{-1/2} 1.15}{k_B}$$ ...
0votes
0answers
52views
Entropy and local flow of time
I have little training in physics or mathematics beyond HS and early undergrad long ago so apologies for any fundamental misconceptions and/or sloppy use of terms. As I understand, the flow of time ...
0votes
0answers
53views
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
2votes
0answers
79views
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}}^...
- 159
4votes
1answer
879views
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
2votes
5answers
589views
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 ...
- 417
0votes
0answers
41views
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 ...
- 235
2votes
1answer
157views
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 ...
- 5,545
1vote
1answer
112views
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 ...
- 612
0votes
2answers
153views
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 ...
0votes
0answers
24views
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 ...
1vote
1answer
170views
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
-6votes
1answer
104views
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 ...
