system
Given the following post, respond as if you're commenting on Reddit:
human
What is stopping the speed of light from going faster?
gpt
Time.  Time is stopping things from going faster than the speed of light.   When things are at rest (like, us... relatively speaking, we are hardly moving at all) we experience Time at it's maximum.  Zero velocity == maximum Time.

When something is moving very fast, it experiences time much slower.   As you get closer to the speed of light (maximum velocity), time gets slower and slower.  You cannot go faster than the speed of light, because that would require negative time, and that just does not happen.  Maximum velocity == Zero Time.

Massless particles such as photons, travel at the speed of light (and never slower [1]), and also never experience time.  The very moment that a photon leaves an electron, from its perspective, it arrives at another electron.  Even if, from our perspective, it took millions of years to travel between electrons.

[1] -- well, not quite.   If something does manage to slow down a photon, and Time no longer is zero, the photon becomes a particle with mass.