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Old 08-16-2019, 02:53 PM
Location: Seattle
2,396 posts, read 506,465 times
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Originally Posted by NJ Brazen_3133 View Post
If you are traveling at FTL, and speeding away from gravitational then what happens? Does time speed up since I am in low gravity or does time slow down because I move fast?
FTL is the same as time travel; you'd be breaking causality and none of the usual rules apply.
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Old 08-17-2019, 03:36 PM
Location: Here
1,502 posts, read 371,394 times
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Originally Posted by davidt1 View Post
So if earth rotates or orbits the sun at near light speed, everyone would age very slowly?
If the Earth rotated 'at near light speed' it would fly apart - the centrifugal force would far, far exceed the gravitational attraction holding the planet together.

If the Earth orbited the Sun 'at near light speed' it would fly off into interstellar space - the Solar System's escape velocity from the point of Earth's orbit is well under 1/10th of 1% the speed of light.
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Old 08-18-2019, 10:22 AM
Location: Maryland
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I think there is also some confusion in some of these comments about clocks running slow. Remember that, for someone hurtling along at a good percentage of the speed of light, there is absolutely nothing abnormal to them about their environment; everything is just as if they were sitting still. It is ONLY when an outside reference frame, at rest or dramatically slower to the one in motion, comes into play that things get weird. For the outside person, the one in motion has slow clocks. For the person in motion, all is normal in their moving envelope.

Where I find this particularly paradoxical, is that if you look at it the other way, the guy hurtling past could see the stationary observer as the one in motion instead. There might not even be a way to tell who is the more “stationary” reference frame in space given all the motion happening. Do they see each other’s clocks running slow, the same? Say they were both approaching each other at 0.8C and pass an observer at rest to both of them. What does each see of the other two? Just plain weird stuff.

Another example, if a ship traveling towards earth at 0.8C were to launch a missile at us which leaves that ship at 0.8C, the missle would NOT be approaching earth at 1.6C, the combined speeds of the two. It would be approaching earth still at some fraction of C, maybe 0.92 for example. The equations are readily available and you can plug in the values and see.

Also, this is not my field by a long shot, I just find it mind-bendingly fascinating. If I’ve made a mistake in this and anyone has good references for me as to why, I’d enjoy reading them.....assuming I could understand them

Last edited by LesLucid; 08-18-2019 at 10:31 AM..
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Old 10-14-2019, 08:12 PM
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I am still confused about the aging thing. However, this video helps a lot. About 3 minutes into the video, physics professor Clifford J explains the concept of relativity using his bicycle. This illustration might not work for people who are unfamiliar with the use of metaphors, simile, etc.

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