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Feb2313 08:40 AM
ZapperZ

1 
42,794 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
42,431 
If the effects of gravity are relative to an objects stressenergymomentum tensor, is the equation:
Fg = Gm1m2/r^2...

Jan3114 12:00 AM
Nugatory

3 
534 
Hey guys, I just want to ask a quick question that confuses me a bit regarding the twin paradox. During acceleration,...

Jan3014 04:27 PM
pervect

32 
1,131 
Hello All,
would anyone know an expression for the heat capacity of an ideal gas, moving with relativistic speeds....

Jan3014 10:30 AM
Sunfire

10 
463 
I have a question; If two particles (let's say protons) collide at high speed, they can produce heavy particles, like...

Jan2914 08:10 PM
Herbascious J

7 
567 
...is the impression that "God plays dice with the universe" an illusion?
If all time in the universe is already...

Jan2914 05:29 PM
ZapperZ

12 
929 
I remember I have read somewhere that contravariant/covariant vectors correspond to polar/axial vectors in physics,...

Jan2914 02:38 PM
WannabeNewton

7 
812 
In http://arxiv.org/abs/0808.1081 / Am.J.Phys.77:688694,2009 Bunn and Hogg explain how cosmological redshift can be...

Jan2914 08:33 AM
PAllen

13 
1,110 
We know the equation E=mc^2 which correlates energy to mass.
If we rearrange the equation:
E/m = c^2 , it turns into...

Jan2914 06:03 AM
BruceW

4 
391 
General relativity talks about curvature of spacetime due to mass. What does it actually mean by 'curve'. Is the...

Jan2914 04:55 AM
nalA

24 
1,388 
I found a funny video on youtube, but I am not totally convinced by the argument.
...

Jan2814 05:26 PM
pervect

11 
597 
The Michelson Moorley experiment to detect the presence of aether is the main experiment
that gave rise to the theory...

Jan2814 03:58 PM
Paul77

3 
434 
I've asked this question a few times. This time i have tiny change in the question. Instead of people I'm using...

Jan2814 03:30 PM
PAllen

118 
4,666 
Here is another train and platform example, offered to examine ghwellsjr's view equating what you see with what is...

Jan2814 02:34 PM
phyti

31 
1,056 
Is there a coordinate independent/geometric definition of a tensor density?

Jan2814 10:45 AM
bcrowell

3 
302 
Due to the diffeomorphism invariance of GR ##(M, g_{ab})## and ##(M, \phi_*g_ab)## represents the same physical...

Jan2814 08:37 AM
center o bass

0 
273 
Here's the scenerio: you have box (shape is not necessarily important, but for simplicity we'll say its a cube),...

Jan2814 08:15 AM
PAllen

19 
991 
Yesterday, I read about Hawking's new proposal regarding the firewall paradox.
A more general thought about...

Jan2814 06:09 AM
PeterDonis

4 
481 
Hi,
I would like to share you this video
http://video.mit.edu/watch/michelsoninterferometer6561/
By this...

Jan2814 05:11 AM
powermind

0 
385 
See below. I screwed up the edit and the use of tex.

Jan2714 07:20 PM
TimeFall

3 
301 
Imagine two asteroids which are separed by 1Ly distance. They are in uniform velocity (.9c) with respect to an observe...

Jan2714 01:17 PM
salvador_dali

13 
611 
Hi,
I'm trying to write down the stressenergy tensor for a single photon in GR, but I'm running into trouble with...

Jan2714 11:44 AM
bcrowell

5 
463 
Observers Alice and Bob are hovering far above the event horizon of a block hole. Alice stops hovering and enters...

Jan2714 09:56 AM
PAllen

546 
33,387 
Ive Heard that things can get mass when moving in speeds Close to c. So I have question.
Lets say we have to...

Jan2714 09:38 AM
Drakkith

16 
551 
An intuitive gravity analogy that explains why the moon orbits the earth is, the earth's mass' effect on space creates...

Jan2714 05:09 AM
A.T.

5 
443 
Hi, i'm new to this, so i'm hope this is how this works. But I had a question. I've heard that even theoretically,...

Jan2614 11:09 PM
ZapperZ

18 
1,005 
I have heard many physicists (ex: Michio Kaku) saying "Warp speed" from Star Trek doesn't violate any known physical...

Jan2614 05:31 PM
JesseM

6 
540 
I had a discussion regarding the region of spacetime visible to an observer falling into aSchwarzschild black hole....

Jan2614 03:30 PM
JesseM

18 
1,373 
If the tangent space at p is a true vector space, then it must be that the sum of two vectors is itself a directional...

Jan2614 01:45 PM
WannabeNewton

2 
314 
Hi all. I'm a runofthemill layman—not a student. I've just developed an interest in physics lately and have been...

Jan2614 10:33 AM
Incognito310

20 
1,182 
So I just started taking Modern Physics and we are currently discussing special relativity. And needless to say, its...

Jan2614 09:28 AM
ghwellsjr

13 
656 
Hey everyone, for anyone who saw my thread in the chemistry section you know I'm changing my view point to that of the...

Jan2614 05:45 AM
llynne

5 
516 
Hello,
Lately I have been wondering about the implications of the speed of light being constant for all observers,...

Jan2614 02:19 AM
ghwellsjr

12 
560 
Hello,
I was reading a book about general relativity and I came across these two equations
$$ \begin{align}
...

Jan2514 04:37 PM
direct99

5 
389 
According to general relativity, if a remote observer monitors an object falling onto a black hole, (s)he will never...

Jan2514 03:12 PM
phinds

6 
380 
Hi. I know that space for an object in motion will contract, relative to an observer. We generally read that space...

Jan2514 02:29 PM
Mentz114

62 
1,803 
How do you find the inverse of metric tensor when there are offdiagonals?
More specifivally, given the (Kerr)...

Jan2514 10:48 AM
Nabigh R

4 
569 
Tensors can be of type (n, m), denoting n covariant and m contravariant indicies. Rank is a concept that comes from...

Jan2414 09:50 PM
jcsd

4 
331 
Hi, I'm trying to understand why the metric I've seen for AdS space,...

Jan2414 11:38 AM
copernicus1

0 
236 
From what I learned watching Brian Greene's "Fabric of the Cosmos" episode on Nova, if you look at spacetime like a...

Jan2314 08:56 PM
PeterDonis

3 
459 
This is about Hans Ohanian, "Einstein's E = mc2 mistakes," http://arxiv.org/abs/0805.1400 , a historical paper that...

Jan2314 06:03 PM
bcrowell

0 
253 