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Feb2313 08:40 AM
ZapperZ

1 
37,383 
The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many...

Dec3107 02:06 AM
jtbell

0 
37,141 
If gravity waves are supposed to propagate at c, how could the theoretical warp drive wave propagate at greater than...

Sep1513 06:51 AM
Vanadium 50

4 
489 
A typical formulation of the Einstein equations is
R_{\mu\nu}\frac{1}{2}Rg_{\mu\nu}+\Lambda g_{\mu\nu}=\frac{8\pi...

Sep1513 12:15 AM
WannabeNewton

1 
558 
Given g=\det(g_{\mu\nu}), I find that
\frac{\partial g}{\partial g^{\mu\nu}}=gg_{\mu\nu}
Can someone confirm...

Sep1413 03:46 PM
Bill_K

1 
443 
As I see,I will show you something and I want to explain me who has right.
For example into the run a human walk...

Sep1413 09:30 AM
ZapperZ

22 
1,205 
http://en.wikipedia.org/wiki/Twin_paradox
I read a little bit about this, and am a little bit confused.
I always...

Sep1413 06:57 AM
DaleSpam

4 
550 
Someone published a simple computation of the relativistic shift in Mercury's perihelion (over and above classical,...

Sep1313 08:55 PM
atyy

1 
443 
A long time ago I visualized mass accelerated to the speed of light(or theoretical maximum to this speed) as an...

Sep1313 03:33 PM
bizzder

6 
428 
The CMB used to be gamma rays, right? And now it's microwaves  more redder energy: so where did the rest of the...

Sep1313 08:06 AM
Naty1

18 
1,350 
The contravariant transform seems to be defined by the differential transform from calculus.
...

Sep1313 07:34 AM
HallsofIvy

1 
453 
If light takes 1 year to reach a destination, and it takes a ship 2 years to reach the same destination, how fast is...

Sep1213 01:46 PM
ghwellsjr

8 
852 
Can anyone help me with this thought experiment.
I have a spaceship moving at very close to the speed of light....

Sep1213 10:36 AM
ghwellsjr

13 
618 
General Relativity says that every object that has mass make a curvation to spacetime.
Ι want to ask from what...

Sep1213 06:47 AM
DaleSpam

1 
435 
My first of many GR questions :cool::
If electromagnetism can be incorporated into the standard model, where I...

Sep1113 07:10 PM
atyy

7 
519 
Hi, I am having problems in constructing a stressenergy tensor representing a constant magnetic field Bz in the...

Sep1113 04:38 PM
PeterDonis

12 
655 
I have a question, my bestfriends dad said that if we were driving at 70 mph and then honked the horn, the sound would...

Sep1113 01:29 PM
Nugatory

3 
601 
explain it like im 12 years old.

Sep1013 10:34 AM
jtbell

6 
614 
I read an article a while back, I can't seem to find it now, that stated that photons can deteriorate into smaller...

Sep1013 09:00 AM
Naty1

13 
893 
I know this is a really "dumb" question but I was thinking about the time continuem that moves from left to right...

Sep913 02:37 PM
PeterDonis

11 
801 
It has been said that special relativity calls for light's oneway speed to be exactly c per all inertial coordinate...

Sep813 09:11 PM
DaleSpam

49 
2,716 
Hi,
Consider two fixed points A and B in a frame S. In this frame a person P moves towards the point A and does an...

Sep813 02:38 PM
PAllen

8 
568 
Hi,
Consider an observer S pushing a fork towards a material xaxis as seen in the figure below
According to...

Sep813 01:13 PM
bgq

20 
1,180 
There is a static spherically symmetric perfect fluid solution of the EFE where the energymomentum tensor is...

Sep813 04:22 AM
Mentz114

2 
490 
Hi, I'm new and uneducated. Would like to know how to reconcile spacetime being considered asymptotically flat near...

Sep713 10:43 PM
jbunch

14 
589 
In a different thread the Herglotz Noether theorem was brought up and it was mentioned that this theory implies it is...

Sep713 08:01 PM
yuiop

80 
3,549 
Hi guys! I need help on a problem from one of my GR texts. Suppose that ##\xi^a## is a killing vector field and...

Sep713 03:35 PM
WannabeNewton

4 
755 
The general field equation for GR is
Rab  1/2 gab R = 8πTab
where I am setting G = 1 and c = 1.
Also, the...

Sep713 01:25 PM
Thinkor

3 
495 
Hi!
I am having the following action with an induced metric and a scalar field: $$S = \int dr d^dx \, \left(...

Sep713 09:44 AM
llorgos

0 
355 
Galilean principle of relativity is for sure not absolutely true, isn't it?
Say one has a pool full of water within...

Sep713 06:37 AM
DaleSpam

44 
1,659 
If you had two synchronized clocks in two side by side elevators, and one sat on the surface of the earth in 1 g for...

Sep613 02:49 PM
Nugatory

14 
764 
Hi..
I was reading about the special theory of relativity, and was thinking about interactions and speed of source...

Sep613 02:16 PM
harrylin

9 
639 
Hello PF members!
First of all, let me start off my post by admitting that I have created a duplicate account....

Sep513 10:34 AM
berkeman

3 
668 
The presence of a cosmic string does not lead to gravitational attraction of a particle placed some distance away from...

Sep513 08:49 AM
Bill_K

1 
470 
I'll begin by admitting that I did not scroll through the entire list of threads to see if there was already a post...

Sep513 02:27 AM
RiccardoVen

15 
935 
Ideal rulers in relativity are generally assumed to be consistent with radar measurements. The modern definition of...

Sep513 01:27 AM
pervect

8 
545 
In the equation x = vt it is generally accepted that x and v are vectors and that they have a common eigenvector....

Sep413 06:37 PM
WannabeNewton

21 
1,328 
I have a (probably trivial) question about coordinate charts. I've been studying Sean Carroll's lecture notes on...

Sep413 05:25 PM
Ibix

2 
454 
Can anyone explain about time dilation in a simple way?
I am confused about these facts:
1) If an observer A...

Sep413 04:40 PM
Nugatory

9 
570 
Can anyone give me a geometrical interpretation of the weyl curvature tensor?

Sep413 11:44 AM
WannabeNewton

7 
520 
I have two questions having to do with the Lorentz transformation for the time...some preamble first:
The Lorentz...

Sep413 08:41 AM
ghwellsjr

2 
508 
Gravity is zero at the center of the earth. how come the same set of equations predict the gravity to be infinity at...

Sep413 03:48 AM
Sasikanth9

1 
412 