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Feb2313 08:40 AM
ZapperZ

1 
37,396 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
37,153 
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 
27,416 
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 
415 
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 
335 
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 
793 
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 
418 
I had a discussion regarding the region of spacetime visible to an observer falling into aSchwarzschild black hole....

Jan2614 03:30 PM
JesseM

18 
919 
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 
256 
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 
664 
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 
536 
Is there a simple intuitive description of what the Ricci tensor and scalar represent?
I have what seems to me a...

Jan2614 06:13 AM
pervect

2 
257 
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 
409 
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 
420 
Hello,
I was reading a book about general relativity and I came across these two equations
$$ \begin{align}
...

Jan2514 04:37 PM
direct99

5 
325 
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 
326 
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 
1,270 
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 
314 
With Δt = γ ( Δt' + v Δx' ) For calculating delta t for stationary twin with values of traveling twin.
Is it...

Jan2514 12:35 AM
morrobay

2 
225 
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 
236 
Hi, I'm trying to understand why the metric I've seen for AdS space,...

Jan2414 11:38 AM
copernicus1

0 
182 
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 
313 
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 
197 
I'm concerned about your book. I got up to this part:
And I got very concerned. Although what you say is true,...

Jan2314 03:40 PM
PhilDSP

28 
753 
If spacelike Killing vectors are associated with a conserved momentum, and timelike Killing vectors are associated...

Jan2314 03:26 AM
pervect

3 
288 
Hello all,
I will preface this post with an apology for not putting it in the math/science learning materials...

Jan2214 06:58 PM
bcrowell

6 
303 
There's an equation from Dirac's book on General Relativity that I don't get at all. It isn't derived; instead it's...

Jan2214 06:03 PM
Bill_K

3 
257 
I've been working on a problem that I can't seem to get started on. Here is how it is posted:
Metric of a space is:...

Jan2214 03:47 PM
Libra82

13 
388 
Disclaimer: I have no formal education in physics.
I watched a TedTalk...

Jan2214 02:58 PM
mfb

1 
222 
A quick question I hope:
What would I see from Earth if I sent a rocket to Saturn at nearly the speed of light?
...

Jan2214 02:42 PM
DaleSpam

64 
1,405 
What happens to a particle in a scalar potential U(t,x)? I have been living under a belief that the equation of motion...

Jan2214 01:40 PM
jostpuur

12 
408 
We are trying to find the relative velocity in a Lemaitre observer's frame, when said observer passes an observer...

Jan2214 05:06 AM
Mentz114

15 
436 
After learning about special relativity, and the behavior of light, I do not understand why light is not able to reach...

Jan2114 05:36 PM
stevmg

41 
1,385 
The full Lagrangian for electrodynamics ##\mathcal{L}## can be expressed as ##\mathcal{L}=\mathcal{L}_\textrm{field}+...

Jan2114 09:21 AM
dextercioby

2 
306 
I've written an opensource book on special relativity: http://www.lightandmatter.com/sr/ . It's a work in progress,...

Jan2014 09:35 PM
bcrowell

2 
299 
In the wikipedia page a distinction is made in the definition of the SR 4acceleration between the case with...

Jan2014 03:32 PM
TrickyDicky

4 
320 
I remember reading something, long ago, to the effect that any attempt at creating a CTC would be doomed by energy...

Jan2014 01:30 PM
PAllen

4 
313 
If you don't have any charges or currents, the electromagnetic Lagrangian becomes...

Jan2014 12:33 PM
BruceW

14 
447 
The Lagrangian for a point particle is just L=m\sqrt{1v^2}. If instead we had a continuous distribution of matter,...

Jan2014 11:16 AM
dextercioby

10 
422 
I am just wondering  is spacetime curvature in the presence of energymomentum ( i.e. in interior solutions to the...

Jan2014 08:26 AM
Markus Hanke

4 
256 
Two twins A and (evil) B. Twin A remains "stationary" while evil B goes at near light speed toandfro. Ignoring...

Jan2014 02:36 AM
tom.stoer

10 
411 
Is there any reason to think that that the speed of light could vary with time (taking t=0 at Big Bang), ie, could...

Jan1914 03:27 PM
stevmg

28 
1,282 