I was surprised when I read the OG time machine story by Jules Verne and this was a main plot point, and only later stories hand-waived it. You'd think it was something from later analysis of the idea. Almost like that Verne dude was clever.
this post was submitted on 13 Mar 2025
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Clark Ashton Smith wrote a similar short story where the inventor failed to take it into account. Upon realizing his mistake he decided to just wait for another planet to reach him, turning his time machine into a spaceship.
That's actually a fascinating idea. All interstellar travel is based on the movements of the planets through space time. I bet it alternates between being technically faster and slower than FTL travel since you may have to wait for a time when your destination to pass into the planets past location.
Wow that's a fun thought hole. Constraint certainly breeds creativity!
Classic sci-fi slaps hard
One way to resolve this is to have some kind of multiverse theory where you don't travel back in time to your universe, but to a narrow slection of parallel universes that are also shifted slightly so that it spits you out in an analogous location to your initial departure.
that's why you build it like a spaceship 🤷 ez
I hear police boxes and phones booths are popular as well.
Position isn't absolute so if this happens this means you knowingly made the time machine memorize position relative to e.g. the sun rather than the earth.
Tine machine probably moved in its own inertial reference frame. That will actually get you lost in space because the inertial frame does not orbit around, which involves rotation(rotation is intrinsically non-inertial, i.e accelerating). Time machine's frame will be moving in a straight line if its inertial
Or relative to the galactic center. That would put you even further off.
incorrect, that is not what this means. They could have forgotten about the position setting all together. Also why the suns position? it is also moving and non absolute, just like earths. Makes no difference in this meme
All of space is moving, you need to fix a reference point, there's nothing to stop you making it earth
Earth frame isn't inertial
They could have forgotten about the position setting all together.
You're assuming that the time machine would just change the time and keep the position but there is no absolute reference frame, so the time machine should use some reference frame in which it keeps the position constant. It would then be common sense to have the time machine keep the position relative to the earth. Anything else would be pretty dumb, unless you want to use your time machine also for space travel to other planets.
why the suns position
That was just an example. It's either the sun or the center of our galaxy, or some other reference point so if it wasn't the earth then the sun is the next most logical option.
What you're describing is a machine which moves both in time and space. A machine which only moves in time would result in this meme no matter how you twist it.
That isn't possible. Time is as part of space as the other dimensions. Time is distorted by mass, just like space.
You can't move "purely on the Y axis" any more than you can move "purely on the time axis", or vice versa.
Off topic: Why is it a new idea that the observed motion of the universe around us is affected by "faster time" in denser areas of space? Why is that not blindingly obvious? Bwuh?
We can't really say that for certain. The word "space" as we know it means nothing without the idea of relativity. Earth orbits the sun, the sun orbits the center of the Milky Way, which exists in a nest of clusters and super clusters ... and then you get to the edge of the visible universe. My point is, if a universal frame of reference exists, we haven't found it. "Absolutely stationary" isn't something we can test for. Everything that we can observe appears to be moving around something, so can we even responsibly assume that there is a universal frame of reference? Or is it safer to assume that relativity all that there is (i.e. space-time has no boundaries)?
please explain to me how do you think being stationary in space works?
There are two ways of looking at it.
- The time machine is using itself as a point of reference to comply with general relativity. The only way to time travel is to move forward in time. The way to move through time would be to move a lot faster than the Earth, so that every minute for you inside the time machine would equal to many years for earthlings. And if you're moving that fast you'll fly away from Earth.
- The time machine somehow has a knowledge of the whole universe, this way a Newtonian model applies and an absolute point of reference exists. That allows unrestricted travel both forwards and backwards in time, but that also means that the Earth will inevitably move from under the machine to follow its path across the universe.
No matter how you twist it you'll end up all alone in space. You need a machine which can move through both time and space at the same time.
You've got to entangle the same machine first over a massive macro quantum space-time superposition.
See, you get it.
I remember reading about this concept as a kid in a short story Neal Shusterman wrote called Same Time, Next Year. Blew my mind
If space is always expanding, I’d really like to know if a time traveler would experience issues existing in a universe where the space between atoms is different from the one they left.
They are not, that would require changes in the strong force.
They wouldn't; the expansion of space isn't strong enough to change the distance between atoms; the force holding them together overcomes it.
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