# Wouldn't time travel have to account for "space?" **URL:** \ **Category:** Factual Questions\ **Created:** [January 7, 2009, 12:08am UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159 "2009-01-07T00:08:51Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 7, 2009, 1:35pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/41 "2009-01-07T13:35:32Z")
> [@Trocisp](#): > > Ignoring the motion of the milky way galaxy itself, it’s theoretically (and I only say theoretically because I’m not 100%, I’m 99.9%) possible to take into account all of the variables to pinpoint where the Earth, Sun and the rest of the solar system will be in any given amount of time. Simple extrapolation. But in order to get your time machine there, it’d have to move, and need propulsion systems, life support, and everything else a space traveling vessel would need, right? And that space travel part of the journey wouldn’t be instantaneous or nearly so, as is commonly portrayed with time travel. You might “blip” 100 years into the future, but then you’ve got to putt your way to the spot where London is then. ---
**Author:** ![Todderbob](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@Todderbob](https://boards.straightdope.com/u/Todderbob)\ **Post date:** [January 7, 2009, 1:42pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/42 "2009-01-07T13:42:59Z")
> [@WhyNot](#): > > But in order to get your time machine there, it’d have to move, and need propulsion systems, life support, and everything else a space traveling vessel would need, right? And that space travel part of the journey wouldn’t be instantaneous or nearly so, as is commonly portrayed with time travel. You might “blip” 100 years into the future, but then you’ve got to putt your way to the spot where London is then. But if you can travel through time, you can presumably **pop** into a different area of space than you were originally. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [January 7, 2009, 1:54pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/43 "2009-01-07T13:54:40Z")
I’ve seen this subject dealt with in a couple time travel stories, most recently in a Callahan’s novel by Spider Robinson. It usually only gets mentioned in the most painstakingly accurately-written science fiction. Not the most enjoyable or most interesting. Just accurate. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 7, 2009, 1:57pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/44 "2009-01-07T13:57:50Z")
> [@Trocisp](#): > > But if you can travel through time, you can presumably **pop** into a different area of space than you were originally. Why would one presume that? ---
**Author:** ![Todderbob](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@Todderbob](https://boards.straightdope.com/u/Todderbob)\ **Post date:** [January 7, 2009, 2:01pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/45 "2009-01-07T14:01:01Z")
> [@WhyNot](#): > > Why would one presume that? Why not? If you have the technology to travel to a different point in Time, and time and space are linked, why not give you the ability to travel to a different point in Space? SpaceTime and whatnot. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 7, 2009, 2:17pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/46 "2009-01-07T14:17:47Z")
> [@Trocisp](#): > > Why not? Hey, that’s my line! 😃 > [@](#): > > If you have the technology to travel to a different point in Time, and time and space are linked, why not give you the ability to travel to a different point in Space? Sure, as an author, you can do whatever you like (although if you’re appealing to a sf audience, it’d better be internally consistent, if not real world logic.) But I’m asking about real life hypotheticals; would the function of moving yourself about it time also move you about in space? I don’t think it would, and that you’d have to install your Time Machine around a space movement capable ship of some sort. > [@](#): > > SpaceTime and whatnot. I don’t know what that means. ---
**Author:** ![Todderbob](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@Todderbob](https://boards.straightdope.com/u/Todderbob)\ **Post date:** [January 7, 2009, 2:24pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/47 "2009-01-07T14:24:27Z")
> [@WhyNot](#): > > Hey, that’s my line! 😃 Sorry. I couldn’t resist… :smack: > [@WhyNot](#): > > Sure, as an author, you can do whatever you like (although if you’re appealing to a sf audience, it’d better be internally consistent, if not real world logic.) But I’m asking about real life hypotheticals; would the function of moving yourself about it time also move you about in space? I don’t think it would, and that you’d have to install your Time Machine around a space movement capable ship of some sort. In real life physics, I think that if time travel is possible at all, it’s more likely possible via a machine that sits and things travel back and forward _inside_ of the machine (as I mentioned earlier). Of course, I’m a scientific layman, albeit a relatively educated scientific layman. I’m no where near an expert on the issue, and it’s all very difficult for me to grasp. > [@WhyNot](#): > > I don’t know what that means. > **[Spacetime](https://en.wikipedia.org/wiki/Spacetime)** > > In physics, spacetime, also called the space-time continuum, is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualizing and understanding relativistic effects, such as how different observers perceive where and when events occur. > Until the turn of the 20th century, the assumption had been that the three-dimensional geometry of the universe (its description in terms of loca... Space & Time can be combined into one dimension. If you were to phrase it in a way that traveling through time wasn’t simply popping into and out of time at different places, but an actual journey through an other dimension in order to find the corresponding Time **and** location (or time then location, or something to that effect) it could be internally consistent for Sci Fi. How this relates to reality? I’m quite sure it’s not even close. ---
**Author:** ![ExTank](https://avatars.discourse-cdn.com/v4/letter/e/35a633/32.png) [@ExTank](https://boards.straightdope.com/u/ExTank)\ **Post date:** [January 7, 2009, 2:32pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/48 "2009-01-07T14:32:25Z")
> [@OldGuy](#): > > If relativity is correct there is not space and time; there is just space-time a four dimensional space. Time travel would involve moving from some coordinate in space time to another so you would travel through both time and space generally – perhaps by somehow magically swapping your ability to maneuver freely along some space axis for the ability to move along the time axis. > > You might look up Larry Niven’s “The Theory and Practice of Time Travel” and while your at it “The Theory and Practice of Teleportation” for one SF writers attempt to put physics into these subject. This is my understanding. Space & Time are essentially one. Travel in space becomes travel in time, and vice-versa. Ex: You’re in your Time Machine at 1st & Main, Anytown, on 6 Jan. 2009. You set it to take you to 1st & Main, Anytown, on 6 Jan. 1909. If your machine works, you wind up at your destination (and possibly create a paradox), even though there is a century’s worth of planetary & solar system movement, galactic rotation, and even galactic drift within the larger universe. See **Fish’s** post above. Believe it or not, the TV show _Farscape_ addressed this very issue concerning wormhole travel in the episode “Unrealized Reality.” While I’m not a physicist, by my admittedly limited understanding of “How The Universe Works,” they largely got it right. ---
**Author:** ![Hi\_Neighbor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hi_neighbor/32/494_2.png) [@Hi\_Neighbor](https://boards.straightdope.com/u/Hi_Neighbor)\ **Post date:** [January 7, 2009, 2:33pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/49 "2009-01-07T14:33:02Z")
> [@Shawn1767](#): > > Even a short trip to the past or future would have the earth not where it was when you left in your time machine. I’m in a time machine right now - my body. I just moved a few seconds into the future. My body was not displaced. ---
**Author:** ![aldiboronti](https://avatars.discourse-cdn.com/v4/letter/a/9fc348/32.png) [@aldiboronti](https://boards.straightdope.com/u/aldiboronti)\ **Post date:** [January 7, 2009, 2:54pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/50 "2009-01-07T14:54:00Z")
I think you’re all overlooking the simple fact that any ‘time machine’ worth its salt would be engineered to travel through the time/space dimension. Note Dr Who’s TARDIS (Time And Relative Dimension(s) In Space). Thinking about it, it would be impossible for a machine to travel in anything other than a combined time/space dimension. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 7, 2009, 2:57pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/51 "2009-01-07T14:57:59Z")
> [@ExTank](#): > > This is my understanding. Space & Time are essentially one. Travel in space becomes travel in time, and vice-versa. > > Ex: You’re in your Time Machine at 1st & Main, Anytown, on 6 Jan. 2009. You set it to take you to 1st & Main, Anytown, on 6 Jan. 1909. If your machine works, you wind up at your destination (and possibly create a paradox), even though there is a century’s worth of planetary & solar system movement, galactic rotation, and even galactic drift within the larger universe. See **Fish’s** post above. > > Believe it or not, the TV show _Farscape_ addressed this very issue concerning wormhole travel in the episode “Unrealized Reality.” While I’m not a physicist, by my admittedly limited understanding of “How The Universe Works,” they largely got it right. Ah, so “1st and Main, Anytown” are just as important coordinates to set as “6 Jan. 1909” Unlike our favorite DeLorean which only accepts the date as inputs. ---
**Author:** ![Todderbob](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@Todderbob](https://boards.straightdope.com/u/Todderbob)\ **Post date:** [January 7, 2009, 3:18pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/52 "2009-01-07T15:18:23Z")
> [@WhyNot](#): > > Ah, so “1st and Main, Anytown” are just as important coordinates to set as “6 Jan. 1909” Unlike our favorite DeLorean which only accepts the date as inputs. Yeah. But I’m preferential to the traveling within the machine, rather than the entire machine traveling theory. I mean, it just _seems_ more plausible. The only real problem would be that you couldn’t travel back to before the machine was built. But you would never rematerialize or pop into existance in the middle of a boulder or mountain! ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [January 7, 2009, 3:18pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/53 "2009-01-07T15:18:31Z")
So all functioning time machines also have to be teleporters. Can they teleport someone faser than the speed of light? Say, by setting the “time” in the machine to “1 minute ago” and “location” to “Alpha Centauri”? ---
**Author:** ![Todderbob](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@Todderbob](https://boards.straightdope.com/u/Todderbob)\ **Post date:** [January 7, 2009, 3:25pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/54 "2009-01-07T15:25:59Z")
> [@Alessan](#): > > So all functioning time machines also have to be teleporters. Can they teleport someone faser than the speed of light? Say, by setting the “time” in the machine to “1 minute ago” and “location” to “Alpha Centauri”? It’s all theoretical, but sure. Why not? ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [January 7, 2009, 3:27pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/55 "2009-01-07T15:27:21Z")
I mean, of course that’s not \*true \* FTL, because you’d arrive before you left. But it would be de facto FTL, wouldn’t it? Frankly, if that’s what it means, as far as I’m concerned the time travel aspects are merely a side effect. The stars are my destination! ---
**Author:** ![Todderbob](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@Todderbob](https://boards.straightdope.com/u/Todderbob)\ **Post date:** [January 7, 2009, 3:29pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/56 "2009-01-07T15:29:41Z")
Keep in mind, there’s nothing in the laws of physics prohibiting getting from Point A to point B faster than light. The restriction is simply you can’t accelerate past the speed of light (or to the speed of light… that would take infinite energy). ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 7, 2009, 3:30pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/57 "2009-01-07T15:30:05Z")
> [@Trocisp](#): > > It’s all theoretical, but sure. Why not? :mad: 😃 ---
**Author:** ![tanstaafl](https://avatars.discourse-cdn.com/v4/letter/t/ba8739/32.png) [@tanstaafl](https://boards.straightdope.com/u/tanstaafl)\ **Post date:** [January 7, 2009, 3:36pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/58 "2009-01-07T15:36:23Z")
**Trocisp** , it sounds like you are describing the “time machine” from _Primer_. The way it worked was that the machine would be built and turned on, then left for a while. At some later point you climbed into the machine. Time in the machine ran backwards, so if you stayed in the machine 12 hours you wound up 12 hours in the past. The main restriction on the machine was that you couldn’t go back before the time the machine was turned on. ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [January 7, 2009, 4:12pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/59 "2009-01-07T16:12:32Z")
I can’t believe none of you have mentioned the tv series [Seven Days](http://en.wikipedia.org/wiki/Seven_Days_(TV_series)). It was made clear that the reason why we always saw the chronosphere shoot out into space – and why it needed a pilot to steer the thing – was specifically because the earth was in a different place seven days ago than it is today. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [January 7, 2009, 4:48pm UTC](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159/60 "2009-01-07T16:48:38Z")
> [@Revtim](#): > > It seems to require the concept of an absolute location in space, which, it is my understanding, does not exist. That’s why I think it’s impossible. That is impossible, (and meaningless) but computing its position and velocity when the force vectors keeping it on earth are removed isn’t. Forget about the absolute location part. The earth is in orbit, the entire solar system is moving around the galaxy, and the galaxy is moving. A time machine, to stand still, would have to somehow kill all that velocity. Conservation of energy is enough to make it impossible without even beginning to debate absolute position. [Previous page](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159.md?page=2) [Next page](https://boards.straightdope.com/t/wouldnt-time-travel-have-to-account-for-space/480159.md?page=4)