system
Given the following post, respond as if you're commenting on Reddit:
human
What gives light it's velocity?

Bullets need an explosive force; cars need fuel. Any object that i can think of requires an external force to make it move, yet light instantly has a velocity of 186 thousand miles a second without any intervention or apparent force acting upon it.
gpt
Light is made of photons, which have no rest mass.  One of the consequences of relativity is that a particle with no rest mass *must* move at the speed of light, so once the photon is created, it moves at that speed.

Particles with non-zero mass behave differently; they can, in principle, be brought to rest.  Thus a massive particle can exist in a stationary state and in a moving state.

One way to think about this is in terms of energy.  Let's ignore potential energy.  A photon with any amount of energy travels at speed *c*.  Because photons are massless, any amount of energy, no matter how small, can in principle be used to make a photon.  A massive particle will have total energy equal to mc^2 + its kinetic energy.  Thus making such a particle requires a minimum energy of mc^(2), but that energy is not enough to get it to move as well.  Any excess energy above that minimum value, however, will cause that massive particle to have a non-zero speed.  The situation with the photon is limiting case that that rest mass is zero.