it's not so much that you can't go faster than the speed of light, more that from your point of view light always travels at the speed of light,
however fast you yourself are travelling.
So, even if you're bombing along at 0.9c (where c is the speed of light, 3x10^8m/s), the photons that just bounced off you waving will disappear away from you at c. You can
never catch them up, let alone overtake them!
Einstein came up with the idea of a constant speed of light regardless of the observer's motion by imagining catching up with photons, and went on from there to invent Special Relativity and E = mc^2
