# Search results

1. ### Light, Mass, and Black hole question

for particles with a non-zero rest mass... m = \frac{m_0}{\sqrt{1 - \frac{v^2/c^2}}} This equation gives you the mass of a particle relative to you, going at velocity v. particles with a zero rest mass, for example, photons, naturaly travel at the speed of light, they cannot travel slower...
2. ### Some Musings

I dont really know the reason. Wrong, relative to the other, it would not be 400,000 km/s. NOTHING can go the speed of light relative to ANYTHING else. Did you not see Einstein's velocity addition equation that I gave you??? If you use that equation to measure the relative velocity, then you...
3. ### Some Musings

Just like you said in your post, you cant have a reference frame of a photon and neither time nor space exist. Special Relativity doesnt predict what happens at the speed of light, it can only predict what happens as you approach it. From your example, you have 2 speeds, one 300,000 and another...
4. ### Explaining special relativity

Yea...the light clock is the easiest way I can think of explaining time dilation. Its also pretty easy to algebraicly derive the time dilation equation from using the triangle in the light clock diagram. Just explain the fact that the speed pf light is constant to ALL obsevers...and since the...
5. ### Time travel?

Thanks for the links. It was interesting, but unfortunatly talked about time travel assosiated with GR, which was a little over my head. :confused: Very true, this is better known as the Grandfather paradox. But quantum mechanics has a theoritical solution to it...if you went back in time...
6. ### A doubt on centrifugal forces

What do u mean? Dont you consider the sun to be stationary in respect to the solar system?? So why cant you have a stationary star, with another revolving around it?
7. ### Time travel?

Time travel?? I was wondering if its actually theoretically possible to travel back in time. I know its possible to "travel to the future" because of time dilation, but I just dont understand what the deal is with traveling back in time. I've heard many times since I was a little boy, that...
8. ### A doubt on centrifugal forces

Im not sure i understand what you are asking, but i'll answer anyways. If you had 2 planets only, (or 2 stars) you can have a case where one is revolving around the other, or you can have a case where both are revolving around each other, which a lot of binary star systems do. In the first case...