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Relativity FAQ

Sep10-12 10:09 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
 Views: 8,605 Announcement: Two free ways to get Gold Membership! Jan17-12 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 36,683 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 36,542 I always try to assume that pretty much anything I think of has been thought of before, so I am relatively sure that... Aug10-13 06:37 PM arydberg 8 550 Hi everyone. I'd like you to help me make sense of a question I found about the Michelson Morley experiment. This is... Aug10-13 05:36 PM Simon Bridge 7 538 hi In a local inertial frame with g_{ij}=\eta_{ij} and \Gamma^i_{jk}=0. why in such a frame, curvature tensor isn't... Aug10-13 02:03 PM stevendaryl 22 1,009 hi i read an article by S.carlip about quantum gravity, arXiv:gr-qc/0108040v1 , in this article carlip stated: why... Aug10-13 12:40 PM Bill_K 1 352 I'm trying to make a chart that displays how much energy it takes a rocket with x mass to reach Y factors of... Aug10-13 12:45 AM Simon Bridge 10 624 Apologies if this is in the wrong forum: I am reading Biocentrism by Robert Lanza, and one of his arguments is that... Aug9-13 07:55 PM DaleSpam 2 401 hello In MTW excercise 22.6, given a fluid 4-velocity u, why the expression : ∇.u is called an expansion of the... Aug9-13 01:38 PM WannabeNewton 9 477 I was working on the derivation of the riemann tensor and got this (1) ##\Gamma^{\lambda}_{\ \alpha\mu}... Aug9-13 12:53 PM ProfDawgstein 3 449 I have a short question about the derivative of a given EM-Tensor. ##\rho## = mass density ##U^\mu## = 4 velocity... Aug9-13 08:27 AM ProfDawgstein 21 964 Here is an anecdote about Arthur Eddington: So Eddington thought only he and Einstein understood GR, at some point... Aug8-13 04:38 PM Jolb 24 1,143 The cosmological redshift can be understood in terms of time dilation. In an expanding Universe light travels on a... Aug8-13 02:01 PM Drakkith 45 2,142 In Stephane Hawking's book-A Brief History of Time-Stephane says that in the past they used to believe thatthe speed... Aug8-13 11:06 AM Harry Wilson 27 1,133 The following is a shot in the dark. Say we have two perfectly reflecting mirrors with equal mass. Which are... Aug8-13 05:06 AM arnesinnema 7 517 I'm a little confused about when I would use the 4-velocity for a particle on a world line. I got confused the other... Aug8-13 02:06 AM WannabeNewton 1 387 In GR, the geodesic equation for a test particle can be seen in 2 ways. (1) It is a fundamental postulate... Aug7-13 11:46 PM WannabeNewton 7 685 For outside observer, an object falling into black hole seems to freeze at event horizon and never cross the boundary... Aug6-13 09:17 PM WannabeNewton 4 448 Hi, I confused about the relationship between light and c on the one hand and massless particles and c on the other. ... Aug6-13 12:19 PM phinds 6 593 In his paper, Chou et. al., 2010 has demonstrated that an atomic clock at the height of our head ticks faster than an... Aug6-13 02:26 AM harrylin 138 4,508 Hi everyone! I was thinking about gravitational waves and gravitons and I realized that I did not fully understand the... Aug5-13 01:09 PM The_Duck 11 842 Einstein reconfirmed "In the new Kepler study, scientists used the gravitational lensing to determine the mass of... Aug4-13 07:03 PM Mentz114 4 946 I would like to have a Star orbiting a Schwarzschild Black Hole if the the velocity and position vectors in the galaxy... Aug4-13 10:04 AM DaleSpam 10 545 At the moment I'm reading a little bit about the connection between the Lorentz group SO^{+}(1,3) and its covering... Aug3-13 10:56 AM parton 0 402 In the regular hall effect we calculate like this F=qE=qvB then E=vB , now we assume our conductor has width d so... Aug3-13 10:40 AM Nugatory 4 600 I’ve got a question. Say we have a medium traveling through a pipe at speed v. The soundspeed of the medium is vs.... Aug3-13 10:19 AM ProfDawgstein 1 410 hi some black holes are inner and outer horizon!! what's this means? inner and outer? what happen between them? Aug3-13 08:13 AM Naty1 3 785 Hello Forum I have constructing a Michelson Interferometer using sodium light. For viewing the fringes, I have used... Aug2-13 10:51 PM itsnaresh 2 475 I was working on a problem where I had to prove that div(B) remains invariant under lorentz transformations. That... Aug2-13 11:55 AM WannabeNewton 16 865 Why 299,792,458 m/s? Why does light travel at the speed that it does? Aug2-13 11:42 AM Integral 7 838 hi penrose diagram is a map that map infinity to finite region I don't know that how can I find this map for... Aug2-13 09:18 AM sadegh4137 0 359 This is a question on the nitty-gritty bits of general relativity. Would anybody mind teaching me how to work these... Aug1-13 05:53 PM WannabeNewton 4 635 Hello guys! According to relativity, objects with higher kinetic energy have larger mass. Would that affect the... Aug1-13 04:48 PM Bill_K 7 684 Ok, this should be an easy one but it's driving me nuts. When we take the Lorentz transformations and apply them to... Aug1-13 04:29 PM SamRoss 4 700 I want to find the ricci tensor and ricci scalar for the space-time curvature at the earth surface. Ignoring the moon... Aug1-13 03:42 PM WannabeNewton 8 571 Hello! Consider the law of addition of velocities for a particle moving in the x-y plane: ... Aug1-13 12:04 PM littleHilbert 5 531 I have come across a problem which is a homework indeed, but i tried to pack this question up so that it is more... Jul31-13 05:26 PM mfb 1 440 Hello, I have read that cosmological redshift means a photon is being stretchedby space dilation and thus gets... Jul31-13 05:07 PM mfb 23 1,307 From previous threads I have understood that crossing the event horizon of a supermassive black hole is nothing very... Jul31-13 03:06 PM ZapperZ 28 1,416 I am reading through this text http://www.ita.uni-heidelberg.de/~dullemond/lectures/tensor/tensor.pdf and am... Jul31-13 01:48 PM dextercioby 4 355 GR is confusing me ( 1 2 3 ... Last) The main problem is when we say a manifold is curved surely this is a relative concept - curved relative to what? I've... Jul31-13 06:45 AM Mentz114 58 2,715 Is there a Metric for the Sun and Earth other than the Schwarzschild Metric who has the Schwarzschild Radius on the... Jul31-13 06:43 AM Mentz114 2 393