# How does time travel work in the Terminator franchise given the nature of the time travel devices and the movement of the Earth?

Given the mechanism of time travel shown across the Terminator media (films and TV series) - namely, the traveler being sent from a machine to a point where there is no receptor device - is there anything in-Universe that explains how the traveler even appears back on earth, given not only the axial rotation of the earth, but also its movement around the sun?

• I'll take a wild guess and say "no". :-) Same as "why do two entities (people/cyborgs) sent from the same machine do not appear at the same spot?". Might be related to your question, but it's most likely not explained in the canon. Dec 1, 2015 at 2:15
• For general scifi purposes, time travel is tied to the gravity well of the planet your on. Think relativity. Think tidally locked moons. Time travel should not stop gravity from affecting it.
– cde
Dec 1, 2015 at 2:47

In Terminator Genisys, Kyle and Pops have a bit of back and forth on it.

Reese: Just make sure you show up. Don't wanna have to steal someone's pants again.
Pops: I have the Coordinates in San Fransisco, I'll be there.

Spoiler: He wasn't.

This is after they explain that they need a future tech cpu to calculate the Time Displacement Engine.

Pops: There's no governing Technology in this time that can control the Displacement Circuits.
Reese: You needed a CPU from the Future to make it run (Pops Removes T-800's CPU from the detached Skull) And you couldn't exactly use your own.

Reese and Conner leave Los Angeles in 1984. Pops ends up showing up at the right time (2017), at the right location, only to be stuck in San Fransisco traffic.

So the TDE, using a Terminator brain can target a general location as part of its programming of the time travel circuits. Considering how simple it is to calculate rotation and movement using real world math and computers, a future tech cpu would find that easy to do. Mostly accurate planetary movement was made hundreds of years ago in real life. Copernicus's 1543 Heliocentric theory, improving by Kepler's ~1610 Laws of Planetary Motion, which in turn was improved by Newton in 1683 with Newton's Laws of Motion and Newton's Universal Law of Gravitation. Planetary movement, proven by a bunch of primitives with nothing but fancy telescopes.

So the TDE allows travel in both time and space. It just needs to be properly programmed.

• I want to have your babies.
– user27684
Dec 1, 2015 at 2:25
• TDE would need more than just a "simple calculation". It'd need to "scan" the area in the arrival time, due to the changes in the environment (a tree or a building or a highway appearing). It's quite likely that the highway that Sara and Kyle landed on was not there when they left. There is, of course, further problem: if TDE can "scan" the area so you can pick coords, than Skynet could've done a much broader sweep before sending Terminators. And, of course, the problem of two TDEs colliding (one sends someone, then another one sends someone who significantly changes the arrival environment). Dec 1, 2015 at 9:05
• @VedranŠego The original script for T1 showed that the TDE isn't perfect. Another rebel was supposed to go back with Reese, but does because they materialized in the street and not on top. Considering how smart Skynet is, and how advance terminator CPUs are, they could simply extrapolate where it should be, according to historical records. See terminator.wikia.com/wiki/…
– cde
Dec 1, 2015 at 9:16
• "how simple it is to calculate rotation and movement" It isn't quite that simple I think because a location is never absolute. Of course earth orbits the sun, but the sun orbits the galaxy and space itself is expanding ridiculously fast. I think there simply is no way to pinpoint a location in space without describing it in respect to some other object. And then why would you then choose an other object than Earth. If you choose Earth as a reference frame then you don't need to clacluate any movements I guess
– Ivo
Dec 1, 2015 at 14:38
• @cde There are no historical records when one travels to the future (and all the available CPUs came from an alternate future). Dec 1, 2015 at 19:30