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?
No you wouldn’t. Teleporting “instantaneously” to a distant galaxy, where (for convenience) instantaneousness is measured in your current reference frame would mean teleporting to the distant past or the distant future as measured by someone moving at walking speed towards or away from you when you teleported.
If time travel is teleportation through spacetime, you would have to deal with the problem of matter already present (or not present!) at the destination. You might find that local topography has changed over thousands or millions of years, enough to make you end up trapped inside a rock, or falling to your death into a rift which wasn’t there at the start!
I believe this problem was actually mentioned briefly by H. G. Wells in* The Time Machine*; but his time traveler didn’t come up with any solution, and had to rely on pure dumb luck.
Actually, I believe even collision with the air would have killed him, by forcing all sorts of chemical reactions and rupturing of cell membranes, DNA molecules and whatnot. Clearly, space is the place to do this sort of things, if you absolutely must!
He’s making a valid point. What’s the fixed point you’re using to determine what’s moving?
There are no problems with time travel. If there are (were? might be?), you just go back in time to fix them so there was never any problem in the first place.
See, that’s the problem! Whenever a time travel device is invented, there’s always these guys from the future who use it to go back in time and make sure it stays uninvented, simply out of safety concerns! 
Time is a whole separate dimension from length, width, and height. I think the idea is that, spatially, the device isn’t moving at all. It arrives in exactly the same geographical location from which it left. The only movement was in time, not space.
Thing is, a million years ago, that location could be under 1,000 feet of water because conditions were very different at that particular point in time.
You are in a car travelling north at 60 mph and you time travel forward 1 hour-Where are you?
Certainly not on the 405 at rush hour, that’s for sure!
In my view of TT, exactly where you left. Like sending Einstein one minute into The Future at the Twin Pines Mall.
If you go to all the trouble to invent a time machine, and forget to compensate for the movement of the earth, (or it can’t be compensated for), then you’ve just invented the world’s most useless machine. Not much call to time travel to deep space. Even if you used it as a space ship rather than a time ship, it’s a one-way trip. Your movement in the mean time would prohibit you from ever returning home again.
Hey, you could always use it to get rid of toxic or radioactive waste!
There are perfectly reasonable methods of traveling into the future. Time travel is only a problem when you travel into the past. The methods for traveling into the future are by traveling at a significant fraction of the speed of light. So to travel 4 years into the future, you just head for Alpha Centauri at 99.99999% the speed of light, and when you get there a few hours will have passed for you, but 4 years for everyone back on Earth. For another 4 years, just travel back to Earth. Now you’re 8 years in the future! Congratulations.
The methods for traveling into the future don’t involve magically teleporting into the future, they involve changing the speed at which time passes for various different observers. If you could travel 4 years into the future while staying on Earth, you wouldn’t disappear and then magically appear 4 years later. You’d stay right where you are, but time would stand still for you. It would be more like a stasis field where time passed differently rather than a conventional time mechanism.
Going north at 60 mph without a car?
Another interesting point for writers of time travel/teleportation fiction to address. Is momentum conserved?
Smart!
I like it.
If you mean, you, and only you time traveled, without a machine, in a speeding car, then yes. You’ll be two feet above the ground, moving north at 60 mph. Hope you wore a helmet and leather pants.
But if you’re going to posit it that way, you’ll not only be car-less moving north at 60 mph two feet above the ground, but you’ll be naked.
But, as Ignotus asked, is momentum conserved? I would suggest that momentum is compensated by the machine just as spatial movement must be. What good would a time machine be if you ended up popping into the past moving 1000 mph in the opposite direction?
If the proposed time machine can’t compensate for the earth and sun moving, and can’t compensate for momentum and inertia, then the first time someone uses it is the last. They either end up in space somewhere, or dead from slamming into something as soon as they arrive.
Maybe that’s why there are no time travelers here. They’re all dead somewhere in space, or embedded in a mountain somewhere.
Hmm…good short story idea. Space travelers find interstellar space is littered with time machines carrying dead time travelers.
Larry Niven wrote an essay in which he either originated or popularized the concept that if time travel to the past that changes history is possible, history will settle on a pattern where time travel is never invented. If it’s possible to go back and change the past, then people will keep going back to ‘fix’ problems or just to investigate the past. This means that from the perspective of someone living in the world, history will keep changing in a constant blur, though they’ll never notice it because it will keep having always been that way. “Eventually” (from the outside perspective, not from someone inside history) one of those changes will happen to create a world where time travel never gets invented. Once that happens no one can/will/did go back and change history, so it ends up that’s the only history that will actually stick.
Time and space are no longer thought of as separate and absolute. There is only space-time. If you travel backward in space-time, you’d be retracing the path you followed in both space and time to get to the present. Since you didn’t collide with anything on your way here, you wouldn’t have to worry about matter getting in your path on the way back.
You also couldn’t travel elsewhere in the Universe. So Doug and Tony couldn’t possibly have materialized to meet OTT on Alpha Centauri.
What I want to know is: How far back can you go? To your own birth? Your conception? If you went back farther, would your atoms disperse to retrace their own individual paths through space-time?
Niven(?) had a story (possibly a series) with teleportation where it was conserved. Going up or down in altitude heated/cooled you. There was some mechanism (multi-hops? don’t remember) to scrub off the momentum from moving around the glovbe (I recall some sort of chamber submerged in water that sloshed?).
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!