The speed of light is always constant to the observer. No matter what velocity the observer is travelling at, her measurements of the velocity of light will always yield an answer of 3 x 10^8 m/s. In her own frame of reference, the seconds as measured by a caesium clock are always ticking off at precisely the same rate, and light always covers 1 m in 3.333. x 10^-9 seconds. As viewed from earth, her time is running much slower, and her metres are much shorter. And that is why the speed of light is a constant.
This has less to do with E=mc^2, and more to do with Tv = To/sqroot[1-(v^2/c^2)] Please Register or Log in to view the hidden image!
The subject line was a bit off, true... v=d/t is a Newtonian concept. The whole idea of light's velocity being constant is part of why Einstein's Special and General Relativity was and is so hard to understand. v=d/t is quit good when throwing a baseball and 100MPH over a distance of 100/sqrt(2) mi. It doesn't work so well when the baseball goes .99c over interstellar distances. e=mc^2 isn't the essence of relativity; it's just good for PR. Relativity is bit (Please Register or Log in to view the hidden image!) hairier. tata!
Which genius here can tell me why the speed of light is constant in all reference frames, any takers? Or is it too easy so you can't see it- a clue.
i think the constancy of the speed of light "popped out" of Maxwell's equations when he unified electricity and magnetism.
The principle of relativity says that the laws of physics are form invariant in all inertial reference frames. One such set of laws is Maxwell's equations for electromagnetism, which predict a particular speed for electromagnetic waves (i.e. light). Since these equations must hold in all inertial frames, it follows that the speed of light must be the same in all inertial frames.
