| Dodece said: Technically speaking the equation is incorrect. We now know that the speed of light isn't constant. Scientists in the laboratory have managed to slow light down considerably, and via quantum tunneling light can move faster then it would typically move. That isn't to say the equation doesn't work. Just that something thought to be a constant is not in fact a constant. |
Sorry, that's not right. The speed of light in a vacuum IS a constant.
We can already slow light down by having it go through, say, air. or glass, or water. That doesn't affect the c in this formula. We can even get the part of light that's "waving" (the phase velocity) to be far in excess of c, but the rate information travels is the group velocity which has to be less than or equal to c.
Tunneling doesn't make light go faster, it just allows some photons to escape potential wells (barriers that need high energy to cross) with lower energy than you might expect, because of uncertainty in its position.
There are some fringe theories proposing that this formulation is not correct, but there is no evidence for them and afaik General Relativity is still the gold standard formula for long-scale gravity interactions and E=mc^2 is still correct for photon mass-energy equivalence.
