this post was submitted on 13 Mar 2025
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[–] danekrae@lemmy.world 38 points 3 months ago (6 children)

This blew my mind. All those movies!

So, Back to the Future's a bunch of bullshit?!

[–] TheFogan@programming.dev 41 points 3 months ago (1 children)

It's possible to assume that the professor did the math.

But yeah any time machine would also basically have to have space travel built in to compensate.

They knew that when they wrote Dr Who (IE the time travel machine is called a TARDIS (Time and Relative Dimension in Space).

[–] Klear@sh.itjust.works 4 points 3 months ago* (last edited 3 months ago) (2 children)

Nah, this thing with the planet moving under you is stupid because it assumes a fixed reference frame which is not a thing in our universe. Any movement is always relative to something. You can't just "stay in place". Having the Earth move from under you is very arbitrary.

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[–] potoo22@programming.dev 18 points 3 months ago

There's a ton of issues with time travel. That could be one, but most fictional time-travel devices can be said to accommodate for the difference in distance. It would just be boring to explain on-screen.

[–] Carvex@lemmy.world 13 points 3 months ago

floating astronaut with pistol always has been

[–] faintwhenfree@lemmus.org 7 points 3 months ago

That's why doctor who works, its very clear about the fact that TARDIS travels in spacetime, it can do only time, only space or both space and time and they can get away with time traveling and still staying on earth

[–] TachyonTele@lemm.ee 5 points 3 months ago (1 children)

It could be explained as a time and space machine but just saying time machine is easier.

That's how ive always thought of these things in my head.

[–] fushuan@lemm.ee 6 points 3 months ago (1 children)

but imagine if you could set it to the same time but different distance, it would allow you to teleport, that might be too strong.

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[–] surph_ninja@lemmy.world 16 points 3 months ago (3 children)

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.

[–] HurlingDurling@lemm.ee 8 points 3 months ago (4 children)

I was under the impression that gravity was a constant force keeping the atoms closer together

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[–] MonkderVierte@lemmy.ml 4 points 3 months ago

They are not, that would require changes in the strong force.

[–] BrainInABox@lemmy.ml 3 points 3 months ago

They wouldn't; the expansion of space isn't strong enough to change the distance between atoms; the force holding them together overcomes it.

[–] nucleative@lemmy.world 16 points 3 months ago (9 children)

I know we're in a meme community but this did get me thinking... Not only is the Earth spinning but it's also in an orbit around the Sun which is also orbiting around the center of the Milky Way which is moving through space relative to other galaxies and so on.

Do we have enough information to calculate a position in space in the future for Earth without a fixed reference other than current point?

[–] mexicancartel@lemmy.dbzer0.com 15 points 3 months ago* (last edited 3 months ago) (12 children)

That's what einstein said. There is no fixed reference frame, but only relative ones. Every "inertial"(meaning, motion without any external force) frame of reference is equally valid as any other inertial frame movibg with respect to it.

But for sure we can tell earth's orbit is not inertial since circular motion occur, which is due to external force of gravity.

Edit:typo

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[–] NigelFrobisher@aussie.zone 8 points 3 months ago (1 children)

This is why Doctor Who has a time and space machine. Also because the BBC didn’t have the effects budget to show him flying around.

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[–] ssnoer@feddit.dk 5 points 3 months ago

There is not central point in the universe, and no way to calculate a position. Everything is relatove

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[–] OddButNotReally@lemmy.world 15 points 3 months ago

I remember reading about this concept as a kid in a short story Neal Shusterman wrote called Same Time, Next Year. Blew my mind

[–] FatsoJackson@lemmy.ml 14 points 3 months ago (1 children)

that's why you build it like a spaceship 🤷 ez

[–] zod000@lemmy.ml 11 points 3 months ago

I hear police boxes and phones booths are popular as well.

[–] MoonMelon@lemmy.ml 11 points 3 months ago (2 children)

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.

[–] Bittle@lemmy.world 4 points 3 months ago (1 children)

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.

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[–] malle_yeno@pawb.social 10 points 3 months ago

It should be illegal to remind people (me, particularly) about Steins;Gate while they're at work

I can't be fucking crying on the clock, dawg

[–] WeirdAlex03@lemmy.zip 9 points 3 months ago

Should have watched Tom Scott

[–] witty_username@feddit.nl 7 points 3 months ago

Heyy this property features in the accidental time machine by Joe Haldeman

[–] peteypete420@sh.itjust.works 6 points 3 months ago

Oooohh. Thanks for the tip, just added that into my time travelling port o pottie's destination algorithms. Gotta respect the earth be moving and shit.

[–] some_guy@lemmy.sdf.org 6 points 3 months ago (2 children)

Wow, I never thought about that.

[–] ksigley@lemm.ee 7 points 3 months ago

Math is hard.

It's even cooler if you remember we send something to the moon even with all this variables and no calculators humans were able to know where the moon would be

Of course the moon is relatively close but still

[–] Faydaikin@beehaw.org 5 points 3 months ago (1 children)

See, that's a problem they always skip in time-travel movies.

[–] Codeviper828@lemmus.org 4 points 3 months ago* (last edited 3 months ago)

At least in Doctor Who, the T.A.R.D.I.S. can teleport through space as well as through time, solving that problem. But most time machines don't

[–] RabbitBBQ@lemmy.world 5 points 3 months ago (1 children)

It's just another problem with the mechanics of the snap at the end of Avengers: Endgame

[–] JackbyDev@programming.dev 4 points 3 months ago (2 children)

Magic exists in that universe though and they're using some of the most powerful objects in the universe. So like if it's granting a wish, you just wish that everyone comes back to earth or whatever. It's not even really a suspension of disbelief. It feels more silly to think that genius scientists using wish granting artifacts wouldn't remember to account for the movement of the earth through space.

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[–] Pilferjinx@lemmy.world 3 points 3 months ago (1 children)

You've got to entangle the same machine first over a massive macro quantum space-time superposition.

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