Quote (biblecritic @ Jul 2 2014 07:33am)
the speed of light is pretty straight forward
faradays law shows us that an oscillating electric field will generate an oscillating magnetic field , and maxwell showed us that an oscillating magnetic field will generate an oscillating electric field
this is what light is, an electromagnetic wave that flips between electric field and magnetic field, each field generating the other
that wave is carrying energy, and we know from the conservation of energy law that the energy of the wave cant increase or decrease
and it turns out there is only 1 speed that an em wave can move at in order to keep the same energy
if light moved slower, then the electric field would generate a smaller magnetic field, which would generate a smaller electric field, until there was no energy left
if light moved faster, the electric field would generate a larger magnetic field, which would generate a larger electric field, until the energy of the wave was infinite
only at c can the fields carry the same energy, so the fields are limited to c, they cant go any faster or slower
this is also why every observer always see's light moving at the same speed, no matter what their reference frame
because even if you are moving at half the speed of light, and you turn on a torch, the laws of physics work the same for you as everyone else, and the em wave coming out of the torch has only 1 speed it can move at, because if it moved slower or faster it would break the conservation of energy law
That is fairly profound
Its been a while since I took E&M, kinda wish we learned that