All Questions
107
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Does it make sense to talk about time in absence of matter? [duplicate]
The equations of general relativity should predict (although I might be wrong) that in absence of mass the spacetime is everywhere flat. That is, time is the same everywhere. However, I'm not sure ...
- 145
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votes
1
answer
79
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Does time arising from entropy agree with GR?
There's a theory that the direction of time arises from entropy and the correlations (interactions) between bodies. However, I don't see how this would incorporate the effects of General Relativity, ...
- 185
1
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2
answers
71
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How do I interpret the time axis in a diagram with multiple light cones?
Light cones are often drawn on a spacetime diagram that has a directional time axis like the fourth one on this page:
There is a time axis, and all of the light cones are align with it because this ...
- 113
-2
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2
answers
102
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Is spatial distance objective?
While reading some papers on Einstein's theory of relativity, seeing how the flow of time is not the same for everyone, a doubt occurred to me:
Let us imagine a photon moving in a well-defined space ...
8
votes
1
answer
357
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The synchronized clocks on earth's surface: at which observer's rate are they beating?
From what I understand, the time rates (I'm not speaking about absolute times) of all clocks on earth's surface are synchronized. This means that, say, a mobile phone's clock is generally not beating ...
- 3,753
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2
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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
3
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2
answers
297
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Time in the negative mass Schwarzschild solution
I have read that for the Schwarzschild metric solution with $M<0$, something odd happens with the time coordinate. For the constants of motion, $dt/d\tau=e(1 - 2GM/r)^{-1}$ with $M<0$ and $e$ a ...
- 476
2
votes
1
answer
66
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Questions about E. Minguzzi's article on Synchronization (arXiv:1009.3005)
Only recently I learned of E. Minguzzi's article
"Clocks' synchronization without round-trip conditions", [gr-qc: arXiv:1009.3005] ...
(Notably, the article available for download is dated ...
- 4,306
1
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1
answer
56
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Could you take a point on the surface of the earth as the frame of reference in the Hafele-Keating experiment?
I was recently reading about the Hafele-Keating experiment and asking, how does time in the plane which has flow westwards could have passed faster than on the surface of the earth if the frame of ...
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-5
votes
4
answers
171
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Is it possible to define time in a more universal way, such as, time is the outward manifestation of the activities inside an atom? [closed]
Is it possible to define time as the outward manifestation of the activities inside an atom?
For example,
one second is defined as the unperturbed ground state hyperfine
transition frequency of the ...
- 9
2
votes
0
answers
79
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What is Dirac talking about here? [duplicate]
https://www.youtube.com/watch?v=xJzrU38pGWc&ab_channel=mehranshargh
"I might say that my recent work has been very much concerned with Einstein's general relativity and I believe that the ...
- 195
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votes
1
answer
112
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Understanding consequences of spacetime relativity
If I understood right, time flows slower where there is more gravitational force (or to be more precise, as it was pointed out to me, where gravitational potential is lower), compared to where there ...
- 141
-1
votes
1
answer
109
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Quantum Theory and Time [closed]
I read somewhere that quantum theory requires absolute time and not a dynamic time as described in relativity. Can anyone confirm this and further describe in laymen's terms what quantum theorists ...
- 719
1
vote
2
answers
274
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Proper time in a curved space
In special relativity we've the invariant
$$
d s^2=-d t^2 +d x^2 + d y^2+d z^2
$$
For a clock moving along the worldline in question the above equation reduces to $\begin{aligned} d s^2=&-d t^2\...
- 1,270
4
votes
3
answers
1k
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Is there a way to visualize curvature of time?
Is there a way to visualize curvature of time? I mean curvature of space is both mathematically and physically is comprehensible. I have doubt about curvature of time.
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