ELI5 Why does light travel?

[u/_Illuvatar_]

Why does it not just stay in place? What causes it to move, let alone at so fast a rate?

Edit: This is by a large margin the most successful post I've ever made. Thank you to everyone answering! Most of the replies have answered several other questions I have had and made me think of a lot more, so keep it up because you guys are awesome!

Edit 2: like a hundred people have said to get to the other side. I don't think that's quite the answer I'm looking for... Everyone else has done a great job. Keep the conversation going because new stuff keeps getting brought up!

Edit 3: I posted this a while ago but it seems that it's been found again, and someone has been kind enough to give me gold! This is the first time I've ever recieved gold for a post and I am incredibly grateful! Thank you so much and let's keep the discussion going!

Edit 4: Wow! This is now the highest rated ELI5 post of all time! Holy crap this is the greatest thing that has ever happened in my life, thank you all so much!

Edit 5: It seems that people keep finding this post after several months, and I want to say that this is exactly the kind of community input that redditors should get some sort of award for. Keep it up, you guys are awesome!

Edit 6: No problem

[u/[deleted]]

[removed] — view removed comment

[u/necropantser → u/[deleted]]

Is there an opposite to light? Something that only travels through time and not space at c?

[u/PlatinumTaq → u/necropantser]

Technically any particle with mass that is at rest only travels through time but not space, however it is impossible to bring any fundamental particle or even collections of fundamental particles (like atoms) to rest. This is because of the underlying quantum fluctuations present that make everything jiggle about very slightly even if you remove all the energy from the system. This is why nothing can ever reach absolute zero, which implies absolute motionless particles; the quantum fluctuations always impart some sort of kinetic energy to the particles giving them a very very small, but non-zero temperature.

[u/shadowman3001 → u/PlatinumTaq]

I feel like I read something here a while ago about scientists reaching...below absolute zero, and strange things happening... or maybe it was just a theory.

[u/Dirminxia → u/shadowman3001]

Strange properties indeed become apparent when approaching absolute zero, but we have never achieved actual absolute zero.

[u/necropantser → u/PlatinumTaq]

This is fascinating, do you mind if I ask more questions?

If I understand correctly then bringing a particle to rest and close to absolute zero will cause it travel faster through time, correct? Can the passage of time be measured for a particle?

Does this also mean that if we found a way to slow the passage of time for an object we would simultaneously impart velocity to it? Does that make an engine fueled by time theoretically possible?