Why does light even move? what force makes it move at insane speed?
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I think it’s easier to explain if you think of light as a wave. Imagine you’re holding a rope tired to a pole and it’s stretched so that it stays horizontal. If you shake your end of the rope, you’ll make waves in the rope; you can watch the shaking move down the rope to the other side. Making light is kind of like shaking one “end” of the electromagnetic fields. The shaking will continue moving to the other end.
What makes it so fast? Imagine the rope gets heavier. The shaking will take longer to move to the other side than it did with a light rope. The speed of the waves is dependent on the rope. In the case of light, the speed of light is just dependant on the speed ripples can go through the EM field (how “heavy” the EM field is).
Fun fact: the matter the light is traveling through can change how fast the EM field ripples which actually slows down or speeds up light (light travels slower through water than air, which is part of why things look funny through a flat of water). Think of that as a rope with changing thickness… waves go faster through the lighter/thinner parts than through the heavier/thicker parts.
If you think of light as a particle, then the simplest version of the answer to this is that from our perspective photons are always made with momentum; no force has to make them move, they’re just already moving. The “insane speed” maybe makes a bit more sense if you remember that a photon is insanely light (as in, not heavy), so it doesn’t take much energy to make it go that fast.
Things get pretty trippy if you keep going with the particle view, though, because it doesn’t do a good job of explaining why photons speed up when they leave your glass of water and enter the air. If you dig into that too far, you’ll realize the answer is, essentially, that photons can only exist if they’re going at the speed of light; otherwise they don’t make any sense at all because they have no mass. Relativity is weird that way.
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