# Special & General Relativity

- Dependence of various physical phenomena on relative motion of the observer and the observed objects. Exp. & theo. theories of relativity
 Meta Thread / Thread Starter Last Post Replies Views Views: 1,513 Announcement: Follow us on social media and spread the word about PF! Jan16-12 Before posting anything, please review the Physics Forums Global Guidelines. If you are seeking help with a... Feb23-13 08:40 AM ZapperZ 1 42,388 The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many... Dec31-07 02:06 AM jtbell 0 42,035 We are trying to find the relative velocity in a Lemaitre observer's frame, when said observer passes an observer... Jan22-14 05:06 AM Mentz114 15 599 After learning about special relativity, and the behavior of light, I do not understand why light is not able to reach... Jan21-14 05:36 PM stevmg 41 1,772 The full Lagrangian for electrodynamics ##\mathcal{L}## can be expressed as ##\mathcal{L}=\mathcal{L}_\textrm{field}+... Jan21-14 09:21 AM dextercioby 2 369 I've written an open-source book on special relativity: http://www.lightandmatter.com/sr/ . It's a work in progress,... Jan20-14 09:35 PM bcrowell 2 375 In the wikipedia page a distinction is made in the definition of the SR 4-acceleration between the case with... Jan20-14 03:32 PM TrickyDicky 4 380 I remember reading something, long ago, to the effect that any attempt at creating a CTC would be doomed by energy... Jan20-14 01:30 PM PAllen 4 356 If you don't have any charges or currents, the electromagnetic Lagrangian becomes... Jan20-14 12:33 PM BruceW 14 528 The Lagrangian for a point particle is just L=-m\sqrt{1-v^2}. If instead we had a continuous distribution of matter,... Jan20-14 11:16 AM dextercioby 10 498 I am just wondering - is space-time curvature in the presence of energy-momentum ( i.e. in interior solutions to the... Jan20-14 08:26 AM Markus Hanke 4 318 Two twins A and (evil) B. Twin A remains "stationary" while evil B goes at near light speed to-and-fro. Ignoring... Jan20-14 02:36 AM tom.stoer 10 480 Is there any reason to think that that the speed of light could vary with time (taking t=0 at Big Bang), ie, could... Jan19-14 03:27 PM stevmg 28 1,505 I want to ask General Relativity is a force or Its a theory which explains how to space-time curve and space-time... Jan19-14 02:37 PM A.T. 1 300 Hi, In his original paper, Schwarzschild set the "'equation of the determinant" to be: |g|=-1. In other words, he... Jan19-14 02:09 PM Rob Sfic 17 820 A satellite orbiting the globe at some 300 miles at 18000 mph. Does the clock on the GPS tick slower or faster than... Jan19-14 12:04 AM stevmg 2 293 If I start with the standard FRW cosmology equations, {\eqalign{ 3\dot a^2/a^2&=8\pi\rho-3k/a^2\cr 3\ddot... Jan18-14 11:23 PM stevmg 5 452 In the special relativity the conservation of energy and momentum is represented by the equation:... Jan18-14 07:02 PM WannabeNewton 21 841 Hi All, Long time no post! I've asked a highly-related question to the one I'm about to ask here, but there's a... Jan18-14 12:42 PM phyti 34 1,882 Ok folks, I've taken a stab at the Latex thing (for the first time, so please bear with me). I've mentioned before... Jan18-14 09:49 AM grzz 3 323 If I start with the stress-energy tensor T^{\mu\nu} of the electromagnetic field and then apply energy-momentum... Jan17-14 11:05 AM WannabeNewton 5 625 According to Wikipedia, This definition doesn't sit well with me. Flux is defined as the rate that something... Jan16-14 10:31 PM pervect 10 518 Here is a excellent book on special relativity and world lines. ... Jan16-14 08:56 PM arydberg 0 336 Length and distance in SR ( 1 2 3 ... Last) I would appreciate views on the following understanding of length and distance in SR, restricted here to inertial... Jan16-14 04:52 PM PAllen 73 2,827 If gravitational waves cause fluctuations in space time, than could all gravitational waves, large or small all would... Jan16-14 03:32 PM ilikescience94 0 282 So I've been reading Einstein's theory of relativity, and at one point when discussing the Lorentz equations' proof... Jan16-14 12:45 PM DaleSpam 3 322 Does \eta^{\alpha \beta}=\eta_{\alpha \beta} in all coordinate systems or just inertial coordinate systems? Jan16-14 11:43 AM dEdt 3 342 I want to know how force works in relatvistivc mechanics.I searched it and I know the formula but I didn't know how it... Jan16-14 12:34 AM Agerhell 19 1,062 If the space around the earth is curved according to general theory of relativity no lateral force is required to put... Jan15-14 05:00 PM A.T. 6 368 I never seen any intuitive interpretation of the LHS of the equations. I realize the question is a tall order. But i... Jan15-14 04:31 PM DaleSpam 7 475 I'm trying to figure out if there is an deep or simple relationship between the following two facts. (1) A stick,... Jan15-14 01:28 PM bcrowell 6 642 Hi! How this paper relates to the equivalence principle? http://arxiv.org/pdf/gr-qc/0701084.pdf "in contrast to... Jan15-14 09:52 AM .Scott 3 456 Broad title, but really a specific question that I thought should be straightforward, but got stuck. Consider the... Jan15-14 09:47 AM PAllen 2 478 I know E=mc2 essentially means energy = mass. One might think why not just say E = m? But I also know that: Every... Jan15-14 02:38 AM luna4579 10 1,077 The most famous time traveling paradox is the Grandfather Paradox, where the traveler goes back in time to kill his... Jan15-14 01:06 AM Vanadium 50 4 441 If I had a spoked disc made of unobtainium that could be spun up to .9999c outer rim speed, what would it look like as... Jan14-14 07:50 PM pervect 14 697 In a number of threads over the years the idea has been discussed that if odometers were as well defined as (and as... Jan14-14 04:07 PM ghwellsjr 53 2,184 In general relativity, the source of the gravitational field is the "stress-energy tensor" I know that thing is not... Jan14-14 12:31 PM Naty1 28 1,629 If a spacecraft moving near the speed of light has a camera set up inside observing the people in the spacecraft, and... Jan14-14 09:41 AM .Scott 2 642 Let us say that we have small object of mass ##m## at some location far away from the earth (with zero velocity... Jan13-14 10:47 AM PAllen 7 604 Does anyone have any favorite applications of the acceleration four-vector? More specifically, the WP article... Jan13-14 10:22 AM George Jones 3 626 Gravitomagnetism is this thing https://en.wikipedia.org/wiki/Gravitomagnetism Like electromagnetism equations, but... Jan13-14 07:18 AM DaleSpam 48 2,059