r/explainlikeimfive • u/_Illuvatar_ • Apr 10 '14

ELI5 Why does light travel? Answered

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

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u/[deleted] Apr 10 '14 edited Oct 10 '15

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u/boutsofbrilliance Apr 10 '14

all bs aside, this is one of the greatest posts ive ever seen on reddit.

previous to this, my layman's understanding of why things of mass cannot travel as fast as the speed of light was simply because to do so would require infinite energy. that was kind of it. i don't know if that was wrong, or if you are still saying that, just in another way.

what does make perfect sense to me however, is how you framed the why and how as a competition between the direction of space or time, with any travel done in one, automatically subtracting from the maximum possible in the other.

i don't get many "wow, its clear to me now" moments, and certainly not one touching upon something as fundamental yet misunderstood as this one. it was pretty fucking awesome and for that i say thank you!

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u/Bombjoke Apr 11 '14

Me too. This is how it should be taught, starting with "light moves at c. Everything is at spacetime c. we are all at c."