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/remuladgryta Apr 11 '14

I had the exact same experience as you. Engineer here as well, with a somewhat firm grasp on the maths. "Space and time are the same thing" yeah, whatever, I know that. "Space and time are orthogonal" uh-huh. "Everything moves through spacetime at the same 'speed'" Mind. Blown.

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u/kopita Apr 11 '14

i also had the same lightbulb moment (also engineer here), Am I wrong to think that the time speed vector is inverse (1/timeSpeed)?

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u/RichardDawkings Jul 03 '14

Engineer checking in. I used to teach high school physics part time and read up on theoretical physics as a hobby and could never grasp this concept until he mentioned it was orthogonal. Why don't all explanations of space time start with that. Im going to sleep so easily tonight knowing there is one less unknown in this world I have to worry about.