# 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: 89,233 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 40,919 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 40,574 Why do most explanations of the Twins Paradox claim that the twin on the space ship ages less because he is the one... May1-08 04:51 AM Phy6explorer 4 1,701 I'm putting this here since I'm a high school student who has only completed two years (pre-AP and AP) of introductory... Apr30-08 07:30 PM pmb_phy 14 1,779 How is a photon's energy determine in relation to it's wavelength and frequency? For example, 20hz vs. 400ghz... Apr30-08 07:16 PM pmb_phy 4 16,534 I have scanned the simultaneity related posts and cannot find a succinct answer to a question I have - I accept that... Apr30-08 02:05 AM neopolitan 280 33,523 Apparently some crackpot blew some  on a full page ad in a science magazine, claiming to show that there black holes... Apr29-08 08:54 PM cristo 1 900 I quite often hear that GR is formulated in terms of tensors because laws of physics expressed in terms of tensor... Apr29-08 03:17 AM jdstokes 21 3,191 And the 2nd question: Do we know why is the speed of light 3*10^8 m/s? What determines this value? (I'm not asking... Apr29-08 02:18 AM neopolitan 50 15,016 Hi. I am learning special relativity and have decided to take Einstein's train example to practice some... Apr28-08 09:32 PM morrobay 7 4,364 Assume 2 massive bodies are moving away from each other at high speed. Since the gravitons which cannot travel at... Apr28-08 03:22 PM lzkelley 8 3,218 (the story so far … I maintain that, inside an event horizon, there is a useful distinction between "space" and... Apr28-08 06:42 AM DrGreg 34 9,834 Question: 1. A gravitational interaction causes two energy densities to accelerate towards each other. 2. This... Apr28-08 02:54 AM redtree 19 2,346 I understand if this question sounds juvenile, because I thought of it after seeing a science fiction movie called... Apr28-08 01:35 AM JesseM 2 1,335 Lorentz transformation shows that at the speed of light you divide by zero. Photons travel at the speed of light,... Apr27-08 04:42 PM lzkelley 1 1,804 http://psi.phys.wits.ac.za/teaching/Connell/phys284/2005/lecture-01/lecture_01/node13.html But what about induced... Apr27-08 04:17 PM Dropout 3 2,025 Does it make sense for the Ricci Scalar to be a function of the spacetime coordinates? In previous calculations I... Apr27-08 11:46 AM lbrits 3 2,907 Gamma in GR ( 1 2) Does the Lorentz factor show up much (or at all) in general relativity? For instance, is it appropriate to use it as... Apr27-08 11:23 AM shalayka 34 3,952 Hawking gave the black hole entopy equation: (1) S_{BH} = {k c^3 \over 4G \hbar} A where A is the surface area... Apr27-08 10:27 AM Aether 2 1,931 What is the significance of solutions to non-homogeneous wave equations for the scalar and vector potentials that... Apr26-08 11:53 PM Stingray 13 3,602 Blind man's Relativity ( 1 2 3 ... Last) Dear all, I have a simple question. Consider a long railway station. Say 2 km’s long. Station master put two... Apr26-08 11:21 PM newTonn 108 12,523 I have two cathode ray tubes which generate the same amount of beam, i.e., one tube fires off x electrons per second... Apr26-08 08:42 PM HarryWertM 9 2,315 I just want to verify that I have the right mindset here on the subject: p=mv You can increase the momentum as... Apr26-08 04:43 PM pmb_phy 5 1,698 The axis of a spinning gyroscope is observed to be parallel to the x,y plane and at 45 degrees to both the x and y... Apr26-08 02:05 PM Mentz114 11 2,714 Suppose you have a very strong, spinning disc with a diameter of say 10 km in length. At the centre the centripetal... Apr26-08 01:07 PM yoyoq 15 4,349 According to GR, how do changes in the mass of an energy density become reflected in its gravitational field? Is... Apr26-08 12:37 PM Haelfix 9 2,174 Wheel experiment: A balanced wheel has two large masses attached to the rim opposite each other with respect to the... Apr26-08 11:48 AM Wizardsblade 9 1,776 Ok so I'm sitting at 0040 in the AM pondering this...is Time Dilation a constant. For example. It only takes an Object... Apr26-08 06:22 AM Tweek 0 2,482 It occurred to me that I hadn't seen GR developed as a gauge theory in the same way QCD/electroweak are. Are there... Apr26-08 12:31 AM Haelfix 3 3,049 Why, when nearing the speed of light, do objects appear to be shrinking to someone in a different frame of reference?... Apr25-08 10:52 PM rcgldr 1 1,105 question: do the effects of relativity that would manifest on objects approaching the speed of light (increasing mass,... Apr25-08 02:50 PM Usaf Moji 10 2,449 Einstein v. Wheeler's Black Holes John Wheeler who died earlier this month (13 April) not only coined the term ... Apr25-08 05:32 AM pmb_phy 3 1,643 I was wondering about what experiments are planned or being done now to test the properties of gravity, such as is... Apr24-08 11:02 PM Chaos' lil bro Order 3 1,670 i find in the literature 1. space is homogeneous and isotropic and time homogeneous, at least if judged by observers... Apr24-08 10:55 PM Ken G 1 1,249 How can you have an inertial reference frame in which a body can remain at rest or move with constant velocity unless... Apr24-08 11:48 AM hartlw 15 3,581 hi, I just heard about particles travelling faster than speed of light and somthing about cerenkov radiation. Is it... Apr24-08 10:27 AM pam 4 4,086 Are gravitational waves considered "high frequency" or "low frequency"? Let's say, for example, compared to... Apr23-08 05:38 PM Pacopag 0 1,302 I really do not understand WHY the equation is as it is. I understand what the equation means and how important it is.... Apr23-08 04:15 PM peter0302 5 1,166 I am new here didnt find the reply to this before I hope I get lorentz transformations right he said, that... Apr23-08 12:34 PM jtbell 5 1,379 1.) The tests of falling bodies in a frame under constant acceleration prove all masses accelerate to the floor at the... Apr23-08 08:40 AM Chrisc 18 2,400 This is similar to the pole and barn paradox, but different enough that I'm not quite confident in my answer: A... Apr22-08 03:07 AM adimare 9 1,917 Hi, I found myself trapped in a question on Special Relativity for 15 years now. Because of other new theories... Apr22-08 02:48 AM olli 3 1,291