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Disclaimer - I’m not a trained physicist. I just have an interest in the subject so this question is probably going to come across really confusing but I’m trying my hardest to explain.

So firstly, this is my assumption of how time dilation works. So say, you travel in a spaceship at almost the speed of light for one day. You might only spend 1 day at that speed, but because time passes slower for you than people on Earth, so then that 1 day is actually 10 years in Earth time and when you might come back, everyone is 10 years older while you’ve only aged a day.

So given this, how would I achieve the opposite? How could I slow myself down in comparison to everyone else on Earth that me spending 10 years at that speed is actually only 1 day for everyone else?

I ask because there really isn’t an absolute velocity that everyone is travelling at right? We are stationary right now but the Earth is moving around the Sun which is moving around the Milky Way and who knows where that’s orbiting. How can I go slower than how fast I’m travelling currently?

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  • $\begingroup$ It is not about absolute speed, but about relative speed, and both see that the other observer's clock is slower. Only the observer that has to accelerate/decelerate ends up "younger". And you cannot easily accelerate earth like you do with a spaceship. See en.wikipedia.org/wiki/Twin_paradox $\endgroup$ – user126422 Mar 13 '17 at 14:27
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    $\begingroup$ If you move away from Earth at a specific speed, and then you turn around and return to Earth at that same speed, and in turn age only 1 day compared to Earths 1 year, three things could have happened. 1) Time slows down for you and equally so in both directions. 2) Time for you sped up on your trip away from Earth, but slowed down on you return trip. 3) Time for you slowed down on your trip away from Earth, but sped up on your return trip. other. $\endgroup$ – Sean Mar 13 '17 at 22:30
  • $\begingroup$ I forgot to mention - I did the calculations and found that the 1 day outcome occurs in all three cases, so there is no way to tell which of the three events had occurred. ( disregard word "other" at end. it's an edit booboo.) $\endgroup$ – Sean Mar 13 '17 at 22:37
  • $\begingroup$ @sean what about instead of going somewhere and back, you just did orbited the earth at the increased speed $\endgroup$ – RoboShop Mar 14 '17 at 6:23
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No. If you are at rest with respect to the earth, you experience time the same way people on earth do. If you are at motion with respect to the earth, any kind of motion, you experience the time dilation the way you sketched.

The relative motion between you and the earth cannot be "slower" than zero, which is the case when you are at rest with respect to it.

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  • $\begingroup$ Ok I'm not sure I understand what makes the Earth so special here? Cause say if I went from the space ship to the earth then wouldn't I be speeding up time? I'd be experiencing 10 years while the rest of the crew on the ship live 1 day. $\endgroup$ – RoboShop Mar 13 '17 at 14:11
  • $\begingroup$ @RoboShop there is nothing special about Earth, I was only using it as an example because you mentioned. The point is that in general a clock on system A is seen to be moving faster from system B, if A is moving with respect to B. The clocks of A and B mark the same time when they are at rest with each other. $\endgroup$ – glS Mar 13 '17 at 15:17
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    $\begingroup$ absolutely nothing special about Earth. Take any pair of systems A and B and you'll get the same. Have you read the relevant section in the wiki page? I think it explains this rather well. It is important to remember that you are never "speeding up time". Rather, different observers see the time of other systems flow differently than their own, but you cannot speak of any absolute time, because of the very core principle of relativity. $\endgroup$ – glS Mar 13 '17 at 17:27
  • $\begingroup$ And btw, time will always feel the same to you, no matter how yfast or slow you move. It's what you see on others that changes. $\endgroup$ – Bob Bee Mar 14 '17 at 4:26

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