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Feb2313 08:40 AM
ZapperZ

1 
41,707 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
41,349 
Hello,
I need to calculate how accurate a GPS system is using only Special Relativity and a very basic knowledge...

Nov2411 03:53 AM
stevebd1

1 
1,471 
The precession of Mercury is presented as one of the threshold moments for general relativity. Are there any publicly...

Nov2411 12:09 AM
utesfan100

33 
3,868 
Here's a scenario:
A crew travels through the Universe in a spaceship capable of 100% light speed. Relativity...

Nov2311 10:22 PM
DaleSpam

9 
1,153 
I was wondering if someone could help me see where I am messing this up:
Lets say we have our train with a relative...

Nov2311 09:38 PM
Zula110100100

11 
1,292 
I have read that at sea level gravity is the same everywhere on the surface of the Earth. I have also read that...

Nov2311 08:04 PM
YummyFur

6 
1,325 
can you think of gravity as space itself shrinking directionally? and the time dilation effect could be due to the...

Nov2311 07:50 PM
Gomjabbar

2 
1,509 
As I understand it, if you are moving fast enough relative to me, your mass increase will cause you to APPEAR like a...

Nov2311 04:29 PM
pervect

9 
10,405 
The twin who has left earth and travels close to the speed of light in his spaceship, lands back on Earth only to find...

Nov2311 04:19 PM
Passionflower

5 
3,114 
We are currently studying special relativity and using the idea of four vectors.
The position 4vector has been...

Nov2311 01:58 PM
Chestermiller

8 
4,217 
Although I can follow many of the equations, given the Schwarzschild metric, I am stuck on what seems like a...

Nov2311 01:02 PM
PeterDonis

25 
2,846 
Hi all,
I came up with the following problem myself and am trying to solve myself. I haven't seen it in any...

Nov2311 01:01 PM
Passionflower

2 
1,044 
OK, here is the problem formulation, I won't give the "surprsing" answer for a few days.
In an inertial frame, we...

Nov2311 10:00 AM
A.T.

4 
2,803 
Hello,
A recent paper by Cohen and Glashow argued recently that FTL neutrinos would quickly lose energy by pair...

Nov2311 09:41 AM
PeterDonis

5 
1,138 
The Abraham's photon moment p_A=hbar*w/n*c is not Lorentz covariant, but it has been confirmed by several experiments....

Nov2311 07:20 AM
Vanadium 50

153 
16,738 
There is Feynman's example of a mirror in the book QED. To summarize, there is more than one reflection off of a...

Nov2311 01:00 AM
PatrickPowers

0 
805 
1. Can a human travel to distant stars? If the faster you go the slower the time passes for you, then you could...

Nov2311 12:23 AM
Mind Bender

24 
2,219 
Hi all,
I've heard it said that if I could send a message faster than light, then another inertial observer would...

Nov2211 11:18 PM
AdrianMay

3 
965 
It is often said that the paths of light bend, close to a neutron star? What happens if the ray of light is vertical...

Nov2211 11:03 PM
zonde

4 
1,525 
Lets say we have triplets on earth A B and C.
B and C goes from earth together in the same direction at some...

Nov2211 10:42 PM
Janus

16 
2,240 
Hello,
As I'm sure you are aware the Kretschmann scalar (formed by contracting the contravariant and covariant...

Nov2211 11:02 AM
HolyCats

5 
1,574 
Hello,
Let me first say this is not homework, If you do not beleive me you can use any numbers you would like. I am...

Nov2111 11:08 PM
ghwellsjr

13 
1,546 
if light hits a mirror at a 90 degree angle, wouldn't it HAVE to travel slower than the speed of light when it hit the...

Nov2111 11:03 PM
turbo

5 
1,679 
Any faster than light signal can create backward time effect by means of some frames seeing the signal go to the past...

Nov2111 08:31 PM
Fredrik

13 
2,062 
1. Is the universe finite?
2. Could it be just the surface of a higher dimensional object?
3. If something...

Nov2111 05:41 PM
DrGreg

3 
1,096 
What is the reason for this?

Nov2111 03:10 PM
Noja888

13 
2,405 
Because for myself I had some misunderstandings about the behaviour of light.
What are the differences between an...

Nov2111 02:08 PM
DNMock

4 
1,140 
Hi,
I am very new to general relativity and have only just started to learn how to do some very basic manipulation...

Nov2111 11:03 AM
atyy

1 
830 
I'm in the middle of reading 'The Great Equations' by Robert P. Crease (good book) and I've just got to the chapter on...

Nov2111 09:55 AM
ghwellsjr

19 
2,683 
Hello everyone,
I'm trying to calculate the doppler shift in frequency of a moving source. I'm approaching the...

Nov2111 05:44 AM
harrylin

4 
1,387 
Hi, I hear that light always seems to travel at c, but I've failed to completely understand what that means, could...

Nov2111 03:23 AM
harrylin

6 
1,248 
In the weak field approximation,
g_{\mu\nu}=\eta_{\mu\nu}+h_{\mu\nu}
If we make a coordinate transformation of...

Nov2011 09:37 PM
Sam Gralla

4 
961 
If we start from an action in which geometry and matter are nonminimally coupled, can the resulting theory have a...

Nov2011 07:46 PM
atyy

0 
839 
I have been wondering this ever since I was in elementary school and I am hoping for an answer.
The time dilation...

Nov2011 06:00 PM
Nabeshin

1 
1,569 
The theory of Relativity uses a constant c which has the approximate value of 3x108 ms1
The measured speed of...

Nov2011 10:13 AM
Integral

24 
3,502 
Hello, Wald defines, on page 203 the future Cauchy Horizon of a set S\subset M as:
H^+(S)=\overline{D^+(S)}I^
...

Nov2011 03:44 AM
Matterwave

1 
833 
Let’s say some reasonable scientist claims it turns out the speed limit of the universe is actually 8000 meters per...

Nov1911 09:26 PM
ghwellsjr

8 
1,515 
Firstly: Does anyone know at our current level of technology what "small enough not to detect tidal forces" equates...

Nov1911 06:09 PM
PeterDonis

10 
1,388 
Hello. I am trying to get the hang of tensors. I saw this written in http://mathworld.wolfram.com/MetricTensor.html...

Nov1911 05:50 PM
Mazulu

52 
5,327 
Can anyone give an explanation of causality?? Or maybe an article where causality is explained?.

Nov1911 05:50 PM
Matterwave

1 
881 
Hello
So i saw this video on youtube explaining some basics of general relativity and they used example with 2...

Nov1911 04:02 PM
Simon Bridge

6 
1,186 