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Relativity FAQ

Mar11-14 10:20 AM bcrowell

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 Before posting anything, please review the Physics Forums Global Guidelines. If you are seeking help with a... Feb23-13 08:40 AM ZapperZ 1 37,396 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 37,153 Observers Alice and Bob are hovering far above the event horizon of a block hole. Alice stops hovering and enters... Jan27-14 09:56 AM PAllen 546 27,416 Ive Heard that things can get mass when moving in speeds Close to c. So I have question. Lets say we have to... Jan27-14 09:38 AM Drakkith 16 415 An intuitive gravity analogy that explains why the moon orbits the earth is, the earth's mass' effect on space creates... Jan27-14 05:09 AM A.T. 5 335 Hi, i'm new to this, so i'm hope this is how this works. But I had a question. I've heard that even theoretically,... Jan26-14 11:09 PM ZapperZ 18 793 I have heard many physicists (ex:- Michio Kaku) saying "Warp speed" from Star Trek doesn't violate any known physical... Jan26-14 05:31 PM JesseM 6 418 I had a discussion regarding the region of spacetime visible to an observer falling into aSchwarzschild black hole.... Jan26-14 03:30 PM JesseM 18 919 If the tangent space at p is a true vector space, then it must be that the sum of two vectors is itself a directional... Jan26-14 01:45 PM WannabeNewton 2 256 Hi all. I'm a run-of-the-mill layman—not a student. I've just developed an interest in physics lately and have been... Jan26-14 10:33 AM Incognito310 20 664 So I just started taking Modern Physics and we are currently discussing special relativity. And needless to say, its... Jan26-14 09:28 AM ghwellsjr 13 536 Is there a simple intuitive description of what the Ricci tensor and scalar represent? I have what seems to me a... Jan26-14 06:13 AM pervect 2 257 Hey everyone, for anyone who saw my thread in the chemistry section you know I'm changing my view point to that of the... Jan26-14 05:45 AM llynne 5 409 Hello, Lately I have been wondering about the implications of the speed of light being constant for all observers,... Jan26-14 02:19 AM ghwellsjr 12 420 Hello, I was reading a book about general relativity and I came across these two equations  \begin{align} ... Jan25-14 04:37 PM direct99 5 325 According to general relativity, if a remote observer monitors an object falling onto a black hole, (s)he will never... Jan25-14 03:12 PM phinds 6 326 Hi. I know that space for an object in motion will contract, relative to an observer. We generally read that space... Jan25-14 02:29 PM Mentz114 62 1,270 How do you find the inverse of metric tensor when there are off-diagonals? More specifivally, given the (Kerr)... Jan25-14 10:48 AM Nabigh R 4 314 With Δt = γ ( Δt' + v Δx' ) For calculating delta t for stationary twin with values of traveling twin. Is it... Jan25-14 12:35 AM morrobay 2 225 Tensors can be of type (n, m), denoting n covariant and m contravariant indicies. Rank is a concept that comes from... Jan24-14 09:50 PM jcsd 4 236 Hi, I'm trying to understand why the metric I've seen for AdS space,... Jan24-14 11:38 AM copernicus1 0 182 From what I learned watching Brian Greene's "Fabric of the Cosmos" episode on Nova, if you look at spacetime like a... Jan23-14 08:56 PM PeterDonis 3 313 This is about Hans Ohanian, "Einstein's E = mc2 mistakes," http://arxiv.org/abs/0805.1400 , a historical paper that... Jan23-14 06:03 PM bcrowell 0 197 I'm concerned about your book. I got up to this part: And I got very concerned. Although what you say is true,... Jan23-14 03:40 PM PhilDSP 28 753 If space-like Killing vectors are associated with a conserved momentum, and timelike Killing vectors are associated... Jan23-14 03:26 AM pervect 3 288 Hello all, I will preface this post with an apology for not putting it in the math/science learning materials... Jan22-14 06:58 PM bcrowell 6 303 There's an equation from Dirac's book on General Relativity that I don't get at all. It isn't derived; instead it's... Jan22-14 06:03 PM Bill_K 3 257 I've been working on a problem that I can't seem to get started on. Here is how it is posted: Metric of a space is:... Jan22-14 03:47 PM Libra82 13 388 Disclaimer: I have no formal education in physics. I watched a TedTalk... Jan22-14 02:58 PM mfb 1 222 A quick question I hope: What would I see from Earth if I sent a rocket to Saturn at nearly the speed of light? ... Jan22-14 02:42 PM DaleSpam 64 1,405 What happens to a particle in a scalar potential U(t,x)? I have been living under a belief that the equation of motion... Jan22-14 01:40 PM jostpuur 12 408 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 15 436 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 1,385 The full Lagrangian for electrodynamics ##\mathcal{L}## can be expressed as ##\mathcal{L}=\mathcal{L}_\textrm{field}+... Jan21-14 09:21 AM dextercioby 2 306 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 2 299 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 4 320 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 4 313 If you don't have any charges or currents, the electromagnetic Lagrangian becomes... Jan20-14 12:33 PM BruceW 14 447 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 10 422 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 4 256 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 10 411 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 1,282