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How does time travel work with the Earth spinning, the Earth orbiting the Sun and Solar System orbiting around the center of the Milky Way? By the time you fini

by chrsw 7y ago

How does time travel work with the Earth spinning, the Earth orbiting the Sun and Solar System orbiting around the center of the Milky Way? By the time you finish reading this comment you've moved thousands of miles with respect to the galactic center. Or am I missing something?

themodelplumber 7y ago
I like this question. It broke my mental model of time travel because I like to think of time as tied to space, maybe. If you want to rewind a thread of time, you can't really stay in the same place and poof, like Christopher Reeve laying in bed. Because the old hotel isn't in that place anymore, at some physical-historical-galactic-geography level. Maybe it's not meant to work that way though; maybe you can uncouple time and meditate, and your other-conscious travels but in some other way than normal physical travel with forward time, or something like that.
- dorkwood 7y ago
  I think that's a cool idea for a story. It also addresses the question of "if time travel were possible, wouldn't we have seen some time travellers by now?" Perhaps somewhere out there in space is a graveyard of time travellers who ended up landing in the empty void that the Earth once occupied in the time they were travelling to.
stordoff 7y ago
If you can move in time, it seems plausible you could also move in space. According to John Titor: > [T]his problem is actually the most difficult part of time travel. [...] Inside the displacement unit are a series of very sensitive clocks and gravity sensors. This system is called the VGL (variable gravity lock). [...B]efore the unit "leaves" a worldline, it takes a base reading of the local gravity and adjusts the Tipler sinusoid to 'lock' into that position. Although the temporal physics of this statement are wrong, in effect, it holds you to the 'Earth'. During travel, it periodically checks to see that the field has not varied. If it does, it stops and reverses course or drops out at that point. https://www.strangerdimensions.com/2013/02/04/john-titor-the-man-with-the-machine/ https://www.strangerdimensions.com/2013/02/04/john-titor-the...

by chrsw 7y ago

themodelplumber 7y ago

I like this question. It broke my mental model of time travel because I like to think of time as tied to space, maybe. If you want to rewind a thread of time, you can't really stay in the same place and poof, like Christopher Reeve laying in bed. Because the old hotel isn't in that place anymore, at some physical-historical-galactic-geography level. Maybe it's not meant to work that way though; maybe you can uncouple time and meditate, and your other-conscious travels but in some other way than normal physical travel with forward time, or something like that.

dorkwood 7y ago
I think that's a cool idea for a story. It also addresses the question of "if time travel were possible, wouldn't we have seen some time travellers by now?" Perhaps somewhere out there in space is a graveyard of time travellers who ended up landing in the empty void that the Earth once occupied in the time they were travelling to.

stordoff 7y ago

If you can move in time, it seems plausible you could also move in space. According to John Titor: > [T]his problem is actually the most difficult part of time travel. [...] Inside the displacement unit are a series of very sensitive clocks and gravity sensors. This system is called the VGL (variable gravity lock). [...B]efore the unit "leaves" a worldline, it takes a base reading of the local gravity and adjusts the Tipler sinusoid to 'lock' into that position. Although the temporal physics of this statement are wrong, in effect, it holds you to the 'Earth'. During travel, it periodically checks to see that the field has not varied. If it does, it stops and reverses course or drops out at that point. https://www.strangerdimensions.com/2013/02/04/john-titor-the-man-with-the-machine/ https://www.strangerdimensions.com/2013/02/04/john-titor-the...