All Questions
17
questions with no upvoted or accepted answers
2
votes
1
answer
285
views
Does curved spacetime arise from inhomogeneity of gravitational field?
In general relativity textbooks such as Sean Carroll's Spacetime and Geometry, there is often a line of reasoning that goes like this:
Strong equivalence principle states that free falling frames are ...
- 2,997
1
vote
1
answer
117
views
How would a spacecraft travelling near light speed say 0.9c compensate for time dilation in radio communication from spacecraft to earth?
For a spacecraft travelling at 0.9 c for 5 seconds, only 5 seconds would have passed for an observer on Aircraft, while 26.31 second would pass for a stationary observer watching from Earth.
In a ...
1
vote
0
answers
106
views
Energy is the time component of 4-momentum in SR: Proof as per R. Wald's book
This is an excerpt fom R. Wald's book on General Relativity (page 61). I'm not able to understand how he deduces that $E$ must be the time component of $p^a$ with only the assertions made before this ...
- 107
1
vote
0
answers
170
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Rindler Observers
In the process of transition from STR to GR, I'm trying to understand what Rindler observers actually are. Here is how one of the questions from our assignment defines them:
If the distance between B ...
- 67
1
vote
1
answer
113
views
How to tell who is experiencing time slower and who faster when travelling at different speed?
I am trying to understand time dilation w.r.t velocity. Its said that when a satellite travels around earth (at speed more than a synchronized clock on earth which is stationary w.r.t earth), it ...
1
vote
0
answers
89
views
Does time expand?
If the time component of spacetime does not "expand" in the sense that space expands, doesn't that imply that time must already exist in its entirety, past and future? I believe I have seen ...
- 11
1
vote
1
answer
104
views
How two observers on different gravitational fields would observe each other?
As far as I know (from what I have heard) time passes differently (faster or slower) depending on the gravitational field of the observer (or an acceleration). So my question is, if an observer was ...
- 111
1
vote
1
answer
118
views
Reference systems in Special and General Relativity
I am enthralled by the notion of placing observers along with standard identical clocks in a line spaced from one another according to rods of standard length when place next to one another at the ...
- 11
0
votes
1
answer
116
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Time required to reach Black Hole's Event Horizon from outsider perspective?
Let's imagine a pair of particles that is entangled. One (call it $P_1$) is released and then falls to a black hole from a distant $x_0$, (for example $x_0=5r_s$) and velocity $v_0(=1/2c)$, while the ...
0
votes
2
answers
86
views
Time desync with light delay: can we still "look into the future"?
I'm reasonably familiar with special relativity and its effect such as time desynchronization, but I'm having trouble understanding how these effects come into play when we also consider the time for ...
- 728
0
votes
0
answers
26
views
Question on Example 5.9 of Prof. Hartle Gravity textbook
I'm reading the Gravity Hartle book (ed.2003) and I'm having trouble with the question in the last part of Example 5.9 - Frequency Measured by an Accelerating Observer. More specifically the problem ...
- 1
0
votes
0
answers
27
views
Is it correct to say that acceleration slows the frequency of an oscillator?
My question is based on differential aging or differential timekeeping due to, 1) increased speed, and 2) proximity to center of gravitational field. As far as I know, both involve acceleration, and ...
- 1
0
votes
2
answers
92
views
Beginner question special relativity: How many clocks does each observer use when measuring simultaneity?
I am reading a bit about special relativity and saw this picture in a book:
If I understand correctly, the author is using it to demonstrate that when we consider observer Alice at rest, she will ...
- 101
0
votes
0
answers
36
views
If frequency shift is positive then how to interpret it?
Let say lightning is happening at $r=r_{A}$ from center of gravity and our observer at $r=r_{B}$ with $r_{A}>r_{B}$ then if we get frequency shift is positive (by considering let say schwarzschild ...
0
votes
1
answer
52
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Transformation of space at almost the speed of light from different observers
I hear this a lot in documentary movies, where they claim that if you would be able to travel through space near the speed of light, then things would seem squished, the Earth would seem like a 70 ...
