Originally posted by KazetNagorra
Don't you have some text on special relativity? There's got to be something about the Lorentz transformations in there.

http://en.wikipedia.org/wiki/Lorentz_transformation

Originally posted by adam warlock
E=mc^2 is derived with the assumption that the speed of light is constant, so saying that E=mc^2 implies that c is constant is logically wrong (affirmation of the consequent).

In the context of theory I think that the former is quite easy to understand: you don't prove a thing that you assumed in the beginning. Take this example:

I assume that chi ...[text shortened]... we can arrive at E=mc^2 we also can't conclude that E=mc^2 implies the constancy of c.

Don't know how I missed this, thank you for that.

I understand that this is a bit circular, and I can see now why my wording would be incorrect.