Time...

Time is literally measured / created by the oscillation of each space quanta - and it's magnitude compared to the diameter of a space quanta - aka Planck time and Planck length...

Time dilation: close to large masses, spacetime flows very fast around these localized and compressed vortices we call matter. This in turn slows down the frequency of oscillation of each space quanta in that region. Time slows down. This is exactly what we can observe when comparing atomic clocks on earth's surface and those on a GPS-satellite. 

If you try to move with the speed of light through this spacetime fluid, the same issue happens as when approach the speed of sound with an aircraft: the space quanta bunch up in front of the craft, get compressed completely and hence stop their oscillation. Time comes to a halt! That's why you can't go faster than the speed of light. It's the maximum rate of induction within this compressible, superfluid spacetime.