# Time Travel - the problem. **URL:** \ **Category:** Cafe Society\ **Created:** [November 1, 2018, 4:11am UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819 "2018-11-01T04:11:02Z")\ **Posts on this page:** 11\ **Page:** 3
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 1, 2018, 7:37pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/41 "2018-11-01T19:37:42Z")
But of course all this misses the point. There is no preferred reference frame. So suppose your motion with respect to the Earth’s spin is not conserved. And your motion with respect to the Earth’s orbit around the Sun is not conserved. And your motion with respect to the Sun’s motion through the Galaxy is not conserved. And your motion with respect to the Milky Way’s motion through the observable universe is not conserved. And this means…nothing. Because we can say that the Earth is screaming through the Universe at the blistering speed of 99.9999999% of the speed of light, it’s just that the galaxy and the local cluster and the rest of the observable universe are all co-moving with the Earth. So when you teleport forward in time and find yourself 100 billion light years away, now you’ve found your preferred reference frame. And now we can use Einstein’s spinning motion in his grave as a perpetual motion machine for free energy. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [November 1, 2018, 7:45pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/42 "2018-11-01T19:45:30Z")
I’m beginning to believe that time travel will be the Last Solved Problem. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 1, 2018, 8:25pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/43 "2018-11-01T20:25:43Z")
> [@Czarcasm](#): > > If they are fused in that way, would it work the other way around? Instead of instantaneous time travel, let us say there is instantaneous _space_ travel. If you do not stay locked to your position in space when you time travel, would you stay locked to your position in time of you teleport to a distant galaxy? [FTL travel _is_ time travel](http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel). ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [November 1, 2018, 8:25pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/44 "2018-11-01T20:25:57Z")
Note that in any actual travel (not facilitated by wizards), whether you call it space travel, time travel, or space-time travel, you follow a particular path, which could be written down in terms of coordinates. Whether or not there are any planets there where you arrive and how fast you are going when you get there depends on the path you take, and can be predicted given that information. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [November 1, 2018, 8:42pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/45 "2018-11-01T20:42:56Z")
> [@Just\_Asking\_Questions](#): > > Smart! > > I like it. Of course, this presupposes that manufacturing and operating the time machine doesn’t produce equal or greater amounts of waste… 😃 ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [November 1, 2018, 8:48pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/46 "2018-11-01T20:48:08Z")
> [@gdave](#): > > Yeah, but your position relative to what? Spatial position isn’t absolute. > > If your time travel device puts you where the Earth _was_ 1000 years ago, what is that relative to? The Sun? The center of the galaxy? R’lyeh? > [@Alessan](#): > > Relative to where you are now? Did someone fail to understand relativity? ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 1, 2018, 8:59pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/47 "2018-11-01T20:59:12Z")
> [@DPRK](#): > > Note that in any actual travel (not facilitated by wizards), whether you call it space travel, time travel, or space-time travel, you follow a particular path, which could be written down in terms of coordinates. Whether or not there are any planets there where you arrive and how fast you are going when you get there depends on the path you take, and can be predicted given that information. And this is the actual answer to the question. Fictional time machines typically work by having you disappear from one space-time coordinate and re-appear in another space-time coordinate. But that’s not how real things work. Instead things move from one space-time coordinate to another space-time coordinate. Yeah, yeah, quantum teleportation. Except this only physically happens at scales that we scientists call “really really small”. If you’ve figured out a way to make this effect happen at macroscopic scales, then we’re in a land of wind and ghosts and there’s no telling what would “really happen”, because nothing we know about how the universe works will apply any more. Up is down, left is right, next Tuesday is 100 miles away, 1+1=blue, and the speed of light is ice cream. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [November 1, 2018, 9:05pm UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/48 "2018-11-01T21:05:57Z")
> [@Horatius](#): > > No, what I’ve invented is the cheapest way to launch spacecraft ever developed. Time travel (forward or back) however many minutes/hours it takes to get to the approximate altitude you want to be in, then use on-board rockets to stabilize your orbit. Circularizing the orbit is one of the easiest parts of space travel. > > Only if you travel too far, and forget to bring fuel with you. Where you end up is just a function of the movement of the Earth within the Solar System, the movement of the Solar System within the Galaxy, the overall movement of the Galaxy, and the duration of your time jump. Add up all the vectors and plot your arrival time and position as needed. Doesn’t seem to hard. > And if you do it by going backwards in time, you know if you succeeded or not before you even launch! I believe the point is that if you have no initial idea of the point of destination, it would be very hard to collect data as to how it is related to the settings of your spacetime transportator. You could send out a million probes, all equipped with radio beacons and systems to power them, and still not hear from a single one of them in millennia…! ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [November 2, 2018, 2:24am UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/49 "2018-11-02T02:24:42Z")
[https://boards.straightdope.com/sdmb/showthread.php?t=826407&highlight=street](https://boards.straightdope.com/sdmb/showthread.php?t=826407&highlight=street) ---
**Author:** ![Grestarian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grestarian/32/3227_2.png) [@Grestarian](https://boards.straightdope.com/u/Grestarian)\ **Post date:** [November 3, 2018, 12:51am UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/50 "2018-11-03T00:51:38Z")
> [@Czarcasm](#): > > Going north at 60 mph without a car? Uhh…yeah… I kinda did that a couple years back on Park as it approaches 7th. I was on (well, okay, OFF) the motorcycle at the time. Were you there? Did you notice me wave (well, okay, flail) as I passed you? Sorry about the half-hour delay – it was the mini-van driver’s fault! –G! 😃 ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [November 3, 2018, 1:12am UTC](https://boards.straightdope.com/t/time-travel-the-problem/823819/51 "2018-11-03T01:12:09Z")
> [@Czarcasm](#): > > You are in a car travelling north at 60 mph and you time travel forward 1 hour-Where are you? Depends on how close to the North Pole you are. [Previous page](https://boards.straightdope.com/t/time-travel-the-problem/823819.md?page=2)