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Depends on the reference frame. Let's say you're at rest relative to the emitter when the photon is fired, and then the emitter starts moving in the opposite direction. From your frame of reference, the distance between them will be greater than c x time. From the emitter's frame of reference...

I have two rockets, one in point A and another in point B, I'm going to crash one against the other, twice, and I will be observing safely from my laboratory at C, which is right in the middle between A and B. The first time the experiment takes place, I see both rockets rushing forward to...

I think stillwonder named the group the "relativity buster gang", but I wouldn't know anything about that. It's nothing personal, I'm just starting to learn relativity and since you're already denying it, I'm assuming your understanding of the theory is inmense (you'd be surprised, but...

Oh man, arbol, I hadn't realized you were one of those, I will completely stop paying any attention to your posts from now on :smile:

arbol, I just don't believe the constancy of c can be explained in terms of special relativity (which derives it's predictions based on the postulate of the constancy of c.).

Hear to what Feynman has to say about inertia. That's where we are in terms of relativity as far as I'm concerned. We observe something through experimentation (constancy of speed of light in certain inertial frames), assume it will be true in a broader level (constancy of speed of light in all...

I believe the question "why does c move at constant speed in all reference frames?" has no answer. We have experimented and this is what we have observed, relativity studies the consequences of c being constant in every reference frame (and thus far said consequences have not been debunked...

dx'^2 + 2dt'dx'\beta + dt'^2\beta^2 = 0 a = dt'\beta thus dx'^2 + 2adx' + a^2 = 0 (dx' + a)^2 = 0 dx' + a = 0 dx' = -a dx' = -dt'\beta dx'/dt' = -\beta Thanks everyone, I will proceed and slap myself in the head so you won't have to

I must suck at this, so far I have ( \frac{dt' + dx'\beta} { \sqrt{1-\beta^2}} )^2 = dt'^2-dx'^2 \frac{(dt' + dx'\beta)^2} {1-\beta^2} = dt'^2-dx'^2 (dt' + dx'\beta)^2 = (dt'^2-dx'^2) (1-\beta^2) dt'^2 + 2dt'dx'\beta + dx'^2\beta^2 = dt'^2 - dt'^2\beta^2 -dx'^2...

I'm reading Wheeler's spacetime physics and have been doing some newbie SR problems. I thought up what shouldd be an extremely simple problem but am having trouble with the math, I'm sure one of you guys can probably help me out with it. Events A and B occur with a time separation in the...

The people here probably know better books than the ones I've read, but from layman to layman I'd highly recommend Banesh Hoffmann's "Relativity and its Roots", by far the most comprehensible explanation of special and general relativity I've read so far (wikipedia's articles are great too). I...

The main thing to keep in mind when analyzing this paradox (what has helped me the most, at least) is that although in uniformly moving frames one cannot be preferred over the other, this does not happen in accelerated frames: uniform motion is relative, acceleration is not. Imagine the...

Yes, of course, but I was referring to I don't need to avoid hitting a contracted tunnel with rockets launched from a train moving at a relativistic speed either :P

wow, you are fast, I think you actually wrote this before I finished my edit (though it depends on the frame of reference, I guess :P ).

I started thinking a bit about the timer in the middle and I think there's no way one can avoid hitting the back of the tunnel using a signal from the middle of the train. To simplify things, let's imagine a sensor in the middle of the train that reacts to a signal in the middle of the tunnel...

I think can actually understand this if the engineer inside the train calculated when the train will be in the middle from the train's reference frame and setup the rockets be launched simultaneously when this happens. In the train's reference frame, the tunnel is contracted, the rockets are...

nevermind that last post, I just read ht tp://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html and confirmed what I thought :P

Is it safe for me (the observer that sees each ship moving in opposite directions at 0.75c) to say that they're moving away from each other at a speed greater than c? I made the space-time diagram and see no problems with this affirmation, hope you can check it out and tell me if there's...

ah, beautiful, just what I was looking for, for some reason I'm able to picture the addition of velocities with frames that are approaching each other (or the typical example of a guy walking on a train, it's not difficult to invision the length contractions that make sense of the adddition of...

Hello everyone, great to meet you all. My name is Alejandro Di Mare, a computer science bachelor from Costa Rica currently studying music in Pasadena, California. For the past few months physics have captured my attention so greatly I'm thinking about persuing a masters degree in the subject...