Why does light even move? what force makes it move at insane speed?


Why does light even move? what force makes it move at insane speed?

In: 193

It really doesn’t. It seems like it moves, to us, because we’re so massive. To it, however, it’s basically at every point of its path at the same time. Or rather – that path is stitched together into a single point.

It’s really difficult to word it in a non-ridiculous way, because explaining what it would be like if we were to travel at light speed is such a ridiculous concept.

Space and time are two sides of the same coin. All objects move at maximum speed, but sometimes they are moving through space fast and sometimes they are moving through time fast. The faster you travel through one the the slower you travel through the other, though the reason for why these speeds are dependent on mass is yet unknown.

Photons have zero mass, so they move through space at maximum speed, and time at does not pass for them from their vantage point. The opposite is true for black holes. These are extremely massive and time from your vantage point would just about stop the further you go to the singularity if you were to fall into it.

No force pushes the photon. Interestingly, movement at the speed of causality (the speed of light – the fastest that the universe can send signals through itself) is the default state of things in the universe – it just depends on how fast they are moving through space and of they are moving forward through time.

Edit: botched a word

Edit 2: I got something backwards, another user pointed out that time basically stops from an outside perspective for you if you travel into a black hole, not inside. What I meant to say is that from the inside time is going so slow for you but very fast for the rest of the universe that you would see billions of years or more of the future of the universe as you fell in. I think I’m getting that right.

there’s no real “force” involved. forces accelerate and decelerate things. massless particles just kind of… travel at the speed of light.

mass comes from interaction with something called the Higgs field, so you could sort of think of the Higgs field as being the thing that *prevents* things from going at *c*. things without mass don’t interact with this field, so they just… travel at *c*.

(note: light *can* travel slower depending on the material it’s travelling through, but you can’t grab it and slow it down like you could with, say, a cannonball)

Short answer: it just does and no force makes it move

Longer answer:

First things first, light is probably the weirdest simple thing everyone deals with all the time, physically speaking. Light has no mass so it doesn’t need a force to propel it. It doesn’t speed up or slow down. If it exists it travels at the speed of light. It’s easier in this case to think of it as a wave, like on a string or in water. So just like nothing pushes those other waves along after they’re made in their string/water, nothing pushes that light along. They just travel in their speed set by whatever medium they’re traveling through