
Before posting anything, please review the Physics Forums Global Guidelines.
If you are seeking help with a...

Feb2313 08:40 AM
ZapperZ

1 
42,262 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
41,898 
I am looking for a mathematical solution of the following "paradox" regarding the OppenheimerSnyder collapse of a...

May1214 03:33 PM
tom.stoer

3 
366 
It is said that light particle being massless charged particle are not affected by gravity but space, which is...

May1214 02:44 AM
Mordred

14 
647 
I will just describe a common thought experiment to do with special relativity and a question I have about it.
Note...

May1214 12:51 AM
ghwellsjr

6 
512 
Hi,
I am working through Section 5.8 of Sean Carroll's book on GR. Does someone know where I can find the bridging...

May1114 10:48 PM
PeterDonis

1 
285 
As I've understood so far, there are theoretically many types of acceleration.
In all cases except in the Born...

May1114 02:33 PM
Bill_K

2 
455 
Hi,
I am having trouble understanding why Tij can be nonzero for i≠j. Tij is the flux of the ith component of...

May1114 11:28 AM
epovo

4 
594 
If each person exists in an unchanging state in the block universe, and the flow of time is an illusion caused by the...

May1014 02:31 PM
PeterDonis

18 
991 
Greetings,
I'm having some issues with a problem that I is related, though not identical, to Bell's spaceship...

May1014 01:51 PM
HJ Farnsworth

4 
567 
Let's say there's an electric current in a neutral loop of wire. Then we change to a frame where the loop is moving....

May1014 11:53 AM
vanhees71

6 
338 
I've been thinking about the geometry of spacetime itself, and it has really been mindblowing in some way. If space...

May914 04:59 AM
Nugatory

16 
720 
Reading into some special relativity, I have seen E=mc^2 proposed from the assumption of four momentum conservation...

May914 04:04 AM
haael

6 
652 
What would be the example of the twin paradox where there is no acceleration at all ?
Only different periods of...

May814 07:40 AM
DaleSpam

12 
1,708 
Let's say there's a current going around in a superconducting loop in vacuum. Then the loop gets buried in huge amount...

May814 06:45 AM
Bill_K

2 
339 
Length contraction velocity question.
Suppose there are two sets of binary neutron stars in mirrored synchronous...

May814 01:34 AM
PeterDonis

27 
1,220 
As far as I understood the relativity:
1. Massless particles travel at the speed of light.
2. As the speed...

May714 03:23 PM
jtbell

3 
370 
Do you know how could I interpret the Einstein Tensor geometrically (on a general manifold)?
For example the...

May714 02:42 PM
Bill_K

1 
298 
Hello,
I am studying general relativity right now and I am very curious about the Ricci tensor and its meaning. I...

May714 02:16 PM
homeomorphic

6 
453 
Why does one particular 'frame of reference' have fictitious forces (like inertia) whilst another one doesn't.
I...

May714 01:01 PM
DaleSpam

3 
328 
I have spent some time reading other threads and other source. However I could not find any clear derivation of...

May714 07:02 AM
DaleSpam

28 
1,174 
I now have a general understanding of relativity but it threw up a few issues.
I understand that there are no...

May614 11:51 PM
pervect

16 
592 
I am in a zero mass space ship at rest in my chosen frame of reference.
A cylinder with a diameter equal to the sun...

May614 06:34 PM
PAllen

20 
743 
Hello I was reading something the other day and wondered what a twoparticle lagrangian would look like in SR. I'm not...

May614 05:33 PM
Matterwave

10 
468 
Hello. So I always hear people say, "If someone flew in a ship at light speed to a far away star and then came back to...

May614 11:11 AM
ghwellsjr

7 
519 
Consider a pole of 1 light second long in the ##y## direction (the vertical line(s) in the enclosed figure). It is...

May514 11:05 AM
PeterDonis

14 
613 
Hello,
What is the most general cylindrically symmetric line element in the canonical form?
Best regards.

May514 08:31 AM
Bill_K

3 
315 
quote from wikipedia:
"According to the special theory of relativity, it is impossible to say in an absolute sense...

May514 02:50 AM
foobar

16 
863 
In the Feynman lectures, feynman describes the hot plate model of space curvature and shows that light is bent around...

May514 01:14 AM
Sonderval

17 
672 
Hi,
I want to know how can we arrive at the generators of Lie algebra if we have killing equation ?
on the other...

May514 12:32 AM
Matterwave

2 
365 
how can we write and interpret Lorentz generators in light cone coordinates?

May414 10:47 PM
Greg Bernhardt

1 
373 
Hello,
Some knows how to Bondi deduce his radiating line element? I read some papers and there isn't any hint about...

May414 07:21 PM
btphysics

2 
236 
Hi people, please could someone enlighten me on gravitational time dilation. I have read online that some places, such...

May414 04:39 PM
Matterwave

13 
584 
In classical mechanics we can get a nice overview of the dynamics of a system by looking at its positionmomentum...

May414 03:12 PM
WannabeNewton

1 
264 
Light is deflected in a gravitational field and this effect has been measured empirically, confirming the predictions...

May414 09:37 AM
Thinkor

11 
566 
If i am moving at the speed of light, facing the direction that i am going in, everything in front of me appears...

May414 08:02 AM
ghwellsjr

15 
576 
When light is greatly slowed via a medium in laboratories, is it still constant among reference frames?

May314 09:39 PM
1MileCrash

9 
351 
In Dirac's book on GRT, he says the following, p. 45: "In curved space the conservation of energy and momentum is only...

May314 06:37 PM
bcrowell

3 
364 
if we know the relations between time and distance at the moving frame and stationary frame why can't we derive the...

May314 12:09 PM
DaleSpam

4 
284 
If I am understand correctly a moving mass has more energy than a stationary mass. Mass and energy are two forms of...

May314 11:44 AM
PeterDonis

4 
405 
One problem in understanding Special Relativity is that it is intuitively hard to agree with relative simultaneity.
...

May214 02:58 PM
ghwellsjr

60 
3,574 
This is taken from B. Schutz's First Course in General Relativity.
Am I alone in considering this an abuse of...

May214 02:11 PM
PhilDSP

17 
629 