Is there really an absolute reference frame?? According to mechanics as we understand today, all reference frames are equally valid in analysing in the universe, whether measurements are taken relative to the earth/sun..... However if all reference frames are equal, why can't we take measurements relative to a photon of light? And if we did would this not be an absolute reference frame? since the only thing constant in he universe is the speed of light. On another note, if we did take measurements relative to a photon of light, then how would we see the universe? Because according to Einstein's theories, once we travel at the speed of light, length becomes infinitely small. Does that mean relative to light the universe is a tiny object no more than a few cm across? If so why does light take ~ 8min to reach us (since relative to it, it sees the universe being drastically length contracted)?