Sr Definition and 480 Threads

Basic SR question here. But Einstein said that the Speed of light is an absolute constant. Why then do we hear of experiments of laser light and some kind of substance used to SLOW light down to some ridiculously slow speeds? And how water slows down light too. Isn't that "violating" SR? If the...

Someone told me that the normal time dilation formula \Delta t = \gamma t_{0} is not correct and that the time dilation also depends on the distance (I'm not entirely sure of what). Is this true?

Does anyone know of a resolution to the bug and rivet paradox? It is outlined here: http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/bugrivet.html#c1 My first guess is that the rivet does not reach the bug, and the rivet's predictions are wrong because it undergoes infinite acceleration...

Hello everyone. I just kicked myself out of the philosophy section of the forums, and came here looking for some intelligent conversation at last. I'd like to ask a question about relativity that has been puzzling me for a long time. By looking at these threads it's hard (for me anyway) to be...

The Einstein Train Gedunken The observer O’ in the moving frame at M’ arrives at M, the midpoint of A and B in the stationary frame, at t0’ when A and B emit photons. Later a photon from B is detected when M’ is at t1’; the photon from A is detected when M’ is at t2’ in the moving...

I would like to create (with everyone's help) a list of experiments etc that support SR and GR. These should be reproducable experiments, or profound predictions that have been upheld, as well as objects/systems that use SR/GR calculations on an everyday basis. I would predict that such a...

One-off: "Black drop" problem an SR effect? From a Reuters science article (http://story.news.yahoo.com/news?tmpl=story&cid=585&e=1&u=/nm/20040511/sc_nm/space_venus_dc ) This sounds like something one would want to explain through SR - perhaps GR. Any comments from anyone?

Hi guys, Just wanted to know how GR or Sr can determine the answer to this question? How fast does the universe change?

I was reading in my textbook today. And it said that if you compress a spring, the mass increases due to E=mc^2. Technically that sounds right, but where does the mass come from?

Space under construction: The twin ship problem The basic problem is that one of a set of twins leaves Earth to travel at near-light speed, encounters time dilation due to relativity, and returns to find the other twin has experienced more time and is now "older." I wish to discover how to...

An atom is at rest in an inertial reference frame. Suddenly, two photons are emitted from it, at right angles to one another. What is the relative speed of the photons? P.S. Assume they depart from the atom at 299792458 meters per second in the atomic frame, as has been found true by...

Suppose the time dilation formula is true: \Delta t = \frac{\Delta t^\prime}{\sqrt{1-v^2/c^2}} if v = c then the denominator is zero. If the denominator is zero and there is division by zero error then the numerator is nonzero. If the denominator is zero and there isn't division by...

1. Let clock A and clock B be of identical construction, and let them both not be subjected to any force. Let them be at rest with respect to each other. Thus, the relative velocity v is equal to zero. Therefore, using Newtonian mechanics or SR, the clocks tick at the same rate. For the...

1. Suppoes clock A and clock B are of identical construction, both in inertial reference frames, and let the relative speed be zero. Therefore, they tick at the same rate. 2. Let clock B be located inside a ship. As long as the ship doesn't turn on its engines clock B will remain at...

In The Elegant Universe, Briane Greene states that, "Einstein proclaimed that all objects in the universe are always traveling through spacetime at one fixed speed - that of light." If something is sitting still, then all the object's "motion" is in the time dimension. Can someone demonstrate...

In the twin paradox, the twin who has gone into space and back at relativistic speeds supposedly comes back younger than the one who stayed on earth, the reason being that from the Earth twin's reference frame, time has gone more slowly for space twin. However, what has puzzled me is that from...

The SR Question of the Century ================================= ================================= Why has no one simply used two clocks on a table to measure light's one-way speed? ================================= ================================= (Note: No, Roemer did not do it; he...

(1) How is it that the speed of light is measured the same in all inertial reference frames? and (2) For what reason should anyone accept that the speed of light is a universal speed limit.

I have a straight forward question that hopefully somebody can answer. In SR, does the relativistic mass of an object exert an increased gravitational force and if so has it been proven ? All the information that I've found concerning SR discounts its effects when in GR as being irrelevant...

Does SR work/holdup if something were to travel at multiples, instead of fractions, of c? For example, if you travel at .865c for 1 hour, you age one hour, while everyone else on Earth ages 2 hours. But if you travel at 10c for 1 hour, you age one hour but everyone on Earth ages .. I don't...

First of all let me say Hello! as this is my first post. I am a biologist, and have been reading over the very basics of SR for a little while and have a lot of questions on the implications of the theory. I had been asking my questions primarily at a different forum, one that wasn't...

In Einstein's SR the velocity of the light (c) is same in every referent frame. Let us for instance assume we don't know its exact value and try to estimate it. The relative distance suffers contractions depending on the velocity of the frame like this: L=L_0\sqrt{1-\frac{V^2}{c^2}} where L0...

Shortest Proof That SR Self Contradicts In The World Suppose SR is correct, it would then follow that the Lorentz contraction formula is correct. That formula is: L = L0 (1-v^2/c^2)1/2 Suppose that formula is true. As you can see, if v=c, then L = (L0) times zero, hence L=0. Now, by...

Hi all, just discovered the LaTeX feature, so why not play around with it a bit. Quaternions are (sort of) generalized complex numbers where you have one real unit and 3 imaginary units i, j, and k. The basic equation is i^2 = j^2 = k^2 = ijk = -1. Now, if we have a 4-vector \vec{r}...

What kind of experimental predictions does String theory make that differs from the predictions that past theories (QT, SR, GR)make? Paden Roder

Suppose we have 2 inertial systems. We know exactly, that atomic clocks of equal type run at 2 times the different rate on them. Without asking how we know that, assume that this is true. What can we say about these systems without any more data? Seems we can say they have relativistic...

What kind of mathematics knowledge doI have to acquire to understand the technical jargon in special relativity?

One-way speed of light test. I would be grateful for any views you might have on what is a simple test to measure lights speed one-way on the surface of the Earth. The purpose of this test is to prove that the speed of light is affected by the ether wind and as a consequence Einstein's SR is...

Hello, Id like to ask any of you to suggest to me a book which can describe SR & GR straight from its postulates all the way to the forumals used through math but also through detailed explanations. Does such a book exist ? I have almost complted reading elegant universe and it is pretty...

Does SR seem like a total mystery to you? This short book goes through relativistic mechanics and demystifies the so-called "paradoxes" of relativity clearly and concisely. Let's work through it! http://www.physics.nyu.edu/hogg/sr/sr.pdf