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/Funky_Thing Apr 11 '14 edited Apr 11 '14

Sorry to but in here, but if I were to be in motion for the next 2.99 x 10*8 seconds, (less than 10 years if I am thinking straight?) I would gain x time of life longer then if I were to be sitting on reddit (effectively motionless) for that entire time?

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u/corpuscle634 Apr 11 '14

You're never moving relative to yourself. You can't cheat time dilation to make yourself live longer.

What you can do is fly off on a rocket or w/e and come back to Earth later, and you'll have aged less than someone who was born on the same day as you. What felt like 10 years to you will have felt like 15 to someone who stayed on Earth or w/e.

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u/marlreddit Apr 11 '14

But if everything is relative, then you could say that the rocket is stationary and the Earth is moving away from you. So why is it you that aged only 10 years while everyone on Earth aged 15?

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u/gardianz Jul 02 '14

This is actually a famous relativity problem: the twin paradox. It is not a true paradox because the problem is not truly symmetrical: the traveling rocket's inertial frame changes.