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Feb2313 08:40 AM
ZapperZ

1 
41,662 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
41,311 
I'm having a bit of a debate on travelling to AC. I was wondering if someone can post calculatons to show how long it...

Jan2111 01:34 PM
JesseM

17 
2,711 
We have talked about black hole, Unruh and cosmological horizons in these forums....I am wondering if a simple...

Jan2111 11:18 AM
Qreeus

58 
4,516 
Probably this has an easy answer but I can't see it just now, according to the principle of relativity we shouldn't be...

Jan2111 10:52 AM
TrickyDicky

20 
2,173 
let's say a train is traveling at relativistic speed along a straight line to right, and a man is standing in the...

Jan2111 09:05 AM
ghwellsjr

3 
1,008 
I'm confused about how photons are able to split into electrons and positrons. Learning about four dimensional...

Jan2111 08:17 AM
DaleSpam

4 
1,188 
I understand that the distance between 2 points in 2 dimensions
sqrt(x^2 + y^2)
and in 3 dimensions it's
sqrt(x^2 +...

Jan2111 03:12 AM
K^2

4 
1,152 
Suppose we are looking from an inertial frame at two events in a region of spacetime.
The first event A (0,0,0,0) is...

Jan2111 01:52 AM
JesseM

22 
2,056 
What do we mean by "Time is elastic"?
How can we see that time is elastic? Is there anyway to illustrate this?

Jan2011 08:48 PM
BigBang1234

5 
1,634 
If we rearrange Einstein's massenergy equivallency equation we get.
m=\frac{E\sqrt{1\beta^{2}}}{c^{2}}
A...

Jan2011 01:19 PM
Mueiz

8 
1,442 
Hello PF Folks.
So Einsteins Special Thoery of Relativity is based upon two principles (im shortening them for...

Jan2011 09:28 AM
roineust

23 
4,037 
Is there such an animal as an energy continuity equation, or one involving Pmu or the stress energy tensor?
It...

Jan2011 04:09 AM
Phrak

2 
1,827 
1. What are the value of physics constant in Kerr metric, including G, M, c, a, r, or others?
I expect to...

Jan2011 02:01 AM
stevebd1

2 
1,159 
when we say "a topological action", do we only mean that the action is metric free? or is there some other meaning for...

Jan1911 04:46 PM
Naty1

2 
2,082 
i have read quite a bit about gravity waves, and even worked (as a lab tech) on an early GW experiment at LSU back in...

Jan1911 04:36 PM
Naty1

3 
735 
Folks, apologies for reviving a thread that I know has been picked over, but I am a bit confused.
I understand the...

Jan1911 10:26 AM
JesseM

20 
2,488 
Hello. When one is converting between coordinate systems, the Jacobian arises as a necessary consequence of the...

Jan1911 10:20 AM
bcrowell

2 
1,702 
I'm a little confused about what an observer would see while watching something fall into a black hole.
From what...

Jan1911 06:39 AM
lavinia

24 
3,047 
if light can be affected by gravity then why is it said to have no mass? and sience light is affected by gravity.. if...

Jan1911 05:57 AM
DaleSpam

46 
6,842 
To travel by space ship to Andromeda (2.5 million light years) within a life time (say 50 years) you would have to...

Jan1811 03:39 PM
Nabeshin

8 
3,206 
In the LHC, what radial and tangential Gforces does a proton experience where from start to finish? Where would each...

Jan1811 03:10 PM
teve

0 
999 
What are the symmetries determined by FRW spacetime? I guess they include Lorentz symmetry, rotationally and...

Jan1811 01:58 PM
Ich

6 
2,463 
Ok so in Einstein's thought experiment with the train, everything makes sense except...
Einstein is stating that an...

Jan1811 08:29 AM
JesseM

7 
1,047 
Hi,
Is Spacetime inside the Quantum Vacuum or is the Quantum Vacuum inside or fill up Spacetime?

Jan1811 12:25 AM
Alfrez

2 
824 
Is it
\nabla_\mu\nabla_\nu A^\alpha={A^\alpha}_{;\mu\nu}
or
\nabla_\mu\nabla_\nu...

Jan1711 10:32 PM
pellman

3 
1,431 
Hi
I tried using the search function but it keeps timing out on me. Anyway I'm trying to find a good description...

Jan1711 04:59 PM
jason12345

6 
7,940 
This is a two part question. Part 1: I am embarrassed to ask but if someone could please help me. I was thinking about...

Jan1711 10:10 AM
JesseM

23 
2,828 
I was reading in a paper for Chamseddine the following:
"In the past many attempts were made to construct
gravity...

Jan1711 05:04 AM
haushofer

10 
2,453 
I am confused with some of the aspects of time dilation. I read the derivation (the one with the mirrors) and I...

Jan1611 11:08 PM
merry

10 
2,279 
If gravity and acceleration are "cousins," How much faster does time proceed on Earth than floating motionless (or...

Jan1611 08:21 PM
poeteye

10 
2,569 
I'm not very fund of the subject, but what i know is that the Schwarzschild metric and other known solutions for...

Jan1611 03:09 PM
atyy

4 
923 
Why must the 4momentum for photons p^\mu =(\frac{h\nu}{c},\frac{h\nu}{c} \textbf{e}) transform as a 4vector in...

Jan1611 02:09 PM
CompuChip

2 
1,041 
I'd like to start by mentioning that I have very little in the way of experience on the subject, so forgive me if my...

Jan1511 09:23 PM
JesseM

11 
1,475 
So I am an engineering graduate trying to teach myself some general relativity.
I have tried to solve the Einstein...

Jan1511 01:57 PM
Mentz114

4 
2,615 
I do not fully understand the time dialation formula, if the answer is nearer to 1 does that mean time itself under...

Jan1511 01:30 PM
JesseM

3 
834 
In the process of proving that the d'Alembert operator
is invariant under Lorentz transformations, it was...

Jan1511 12:02 PM
elemental09

2 
1,645 
Q.) If i were to travel at 100,000 m/s in an exact horizontal line away from earth for approximately 1 year, when i...

Jan1511 09:33 AM
nismaratwork

4 
1,551 
Suppose you have a source that send a very strong straight beam of light (say laser )
Then you direct the light...

Jan1511 07:47 AM
DaleSpam

59 
7,756 
Is there any merit to the idea that all black hole singularities are in essence one and the same singularity?

Jan1511 02:49 AM
Phrak

13 
1,379 
Can someone give a definition of Killing Horizon along with a few examples that clearly illustrate the difference...

Jan1411 08:44 PM
AEM

0 
782 
Can anyone please tell me what does SPEED OF LIGHT WITH RESPECT TO AN OBSERVER mean?
Some explain it like this: If...

Jan1411 02:43 PM
ghwellsjr

21 
2,553 