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

Feb2313 08:40 AM
ZapperZ

1 
42,391 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
42,036 
Isn't the force of gravity just a result of the shape of space as it is affected by masses within it? Why is it...

Jul2814 08:05 PM
pervect

3 
447 
Hi all. I'm working on a project that requires me to perform calculations in Fermi normal coordinates to certain...

Jul2814 05:47 PM
George Jones

3 
472 
Hi, I am trying to show explicitly the isotropy of the stress energy tensor for a scalar field Phi.
By varying the...

Jul2814 11:27 AM
George Jones

7 
603 
I want to write a sciencefiction story concerning the rapid increase in technology affecting the speed at which...

Jul2814 09:13 AM
ghwellsjr

3 
516 
According to Einstein (e.g. in his book The Meaning of Relativity), a clock rotating about a central clock will be...

Jul2814 12:51 AM
HALON

21 
2,709 
Whatever spacetime be made of strings or some other erotic substance it seems that it doesn't have mass so what causes...

Jul2714 07:39 PM
DaleSpam

13 
562 
Thinking about how so much matter can be squeezed into a singularity, the answer (if I understand correctly) is that...

Jul2714 03:40 PM
Vanadium 50

6 
851 
Hi,
I would be really grateful if someone could help me with two questions I have, both have puzzled me on and off...

Jul2714 10:33 AM
CraigDxHypo

16 
1,024 
I have a metric given as a line element differential ds^2. I have written down the 3x3 matrix with the coefficients. ...

Jul2614 06:56 PM
ChrisVer

8 
500 
What does it mean to boost something along the z axis?
To give some acceleration to it, or to spatially translate it?...

Jul2514 09:52 PM
WannabeNewton

4 
531 
So I was thinking about the space time field and trying to wrap my head around how it is actually bent around a mass. ...

Jul2514 12:38 PM
Nugatory

1 
487 
If velocity is relative and if we cannot say which is moving away from what *objectivley, how do we say that time...

Jul2514 01:23 AM
objecta99

61 
4,147 
It is my understanding that at the most fundamental level, a black hole is simply an object with a gravitational field...

Jul2414 03:31 PM
willoughby

17 
894 
I was reading Einstein's paper "The Foundation of the General Theory of Relativity" and as i understood, he tried to...

Jul2414 08:03 AM
nixed

3 
999 
We measure time based off of atomic vibrations, so time dilation from gravity and velocity are nothing more than...

Jul2414 06:31 AM
DaleSpam

12 
996 
Hello everyone! My question is this: Do we believe time is a constant and forces such as gravity affect our perception...

Jul2314 12:18 PM
DaleSpam

41 
4,096 
Is there a simple intuitive description of what the Ricci tensor and scalar represent?
I have what seems to me a...

Jul2314 11:24 AM
robphy

5 
888 
1. What exactly is the cosmological constant, what is its value (or how do you derive it if it is something that must...

Jul2214 09:43 PM
bcrowell

2 
725 
I was wondering why can't I use formulas from the "Special Relativity" in cases like:
F=mv^2/r Or F=qv•B...

Jul2214 12:56 AM
ghost313

2 
689 
Are there any EXACT solutions similar to Schwarzschild or Kerr in a spacetime which is not asymptotically flat; e.g....

Jul2114 01:36 PM
George Jones

3 
1,319 
Hello everyone. I am attempting to teach myself about special relativity, and have learned a derivation for the...

Jul2114 01:31 PM
toothpaste666

8 
1,110 
I got stuck in deriving the velocity of the particle from the acceleration equation. Here are the details of the...

Jul2014 10:07 PM
ecastro

6 
1,365 
Hello. I'm a layperson curious about physics.
I've read that Quantum Gravity could eliminate the predicted...

Jul2014 06:22 PM
sshai45

11 
1,802 
I have recently gone over the derivation of the stress energy momentum tensor elements for the special case of dust....

Jul2014 04:42 PM
spacetime

4 
1,085 
*Edit: I noticed I may have posted this question on the wrong forum... if this is the case, could you please move it...

Jul1914 10:23 AM
coleman123

8 
2,201 
its been years since I took a physics course so I might have what amounts to a really dumb question. However, I got...

Jul1914 10:21 AM
objecta99

19 
2,143 
Hi
I am a new(ish) student of general relativity. I am currently reading 'Relativitiy DeMystified'
However...

Jul1914 03:58 AM
Nugatory

1 
999 
Hi, I'm trying to derive the displacement of an object with proper acceleration (constant) α.
t is our laboratory...

Jul1814 06:45 PM
pervect

2 
1,251 
Hi
I am teaching myself GTR from Dirac's book...

Jul1814 04:00 PM
WannabeNewton

3 
1,180 
Starting at the beginning and have been having some difficulty explaining the implications of the constancy of the...

Jul1814 03:30 PM
etcota

3 
1,161 
So as the title says, what are the physical reasons behind requiring the connection between tangent vector spaces to...

Jul1814 10:53 AM
stevendaryl

27 
3,704 
Hello Everyone, I am new to this forum.
I understood from sources that spacetime is like a fabric. The massive...

Jul1814 07:48 AM
A.T.

16 
2,541 
What does spacetime curvature means?

Jul1814 05:03 AM
ChrisVer

13 
1,239 
Hi everyone, I just wanted to share this really cool game MIT Game Lab made, it's called A Slower Speed of Light:...

Jul1814 03:15 AM
A.T.

3 
1,643 
Assume observer is located on the surface of the earth with a small amount of time dialation due to gravity. There are...

Jul1714 11:21 PM
rcgldr

2 
1,307 
In "The Hidden Reality", Brian Greene mentions almost offhand that inside the event horizon of a black hole, space...

Jul1714 08:22 PM
PeterDonis

9 
2,192 
Is it possible to assume relativity is still basically correct and reject the btheory of time? Or does a coherent...

Jul1714 05:13 PM
Vanadium 50

2 
1,130 
Hello Forum,
An event is a point in spacetime with spatial coordinates and a time coordinate: (x,y,z,t). An event...

Jul1714 11:33 AM
fog37

7 
1,637 
Please excuse me for being a complete and utter pleb, my meager knowledge of Leonard Susskind's holographic principle...

Jul1614 04:59 PM
pervect

8 
1,939 
Suppose you have a differentiable manifold where at each point you have attached a set of basis vectors...

Jul1614 10:50 AM
George Jones

8 
1,694 