this post was submitted on 13 Mar 2025
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[–] danekrae@lemmy.world 39 points 1 month ago (6 children)

This blew my mind. All those movies!

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

[–] TheFogan@programming.dev 42 points 1 month 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 1 month ago* (last edited 1 month 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 1 month 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 1 month ago

floating astronaut with pistol always has been

[–] faintwhenfree@lemmus.org 8 points 1 month 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 1 month 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 1 month 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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[–] stebo02@lemmy.dbzer0.com 32 points 1 month ago* (last edited 1 month ago) (3 children)

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.

[–] klay@lemm.ee 6 points 1 month ago* (last edited 1 month ago) (2 children)

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

[–] 1rre@discuss.tchncs.de 6 points 1 month ago (1 children)

All of space is moving, you need to fix a reference point, there's nothing to stop you making it earth

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[–] stebo02@lemmy.dbzer0.com 5 points 1 month ago (2 children)

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.

[–] Aux@feddit.uk 7 points 1 month ago (5 children)

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.

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[–] AngryCommieKender@lemmy.world 4 points 1 month ago

Or relative to the galactic center. That would put you even further off.

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[–] nucleative@lemmy.world 17 points 1 month 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 1 month ago* (last edited 1 month 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 1 month 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 1 month ago

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

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[–] surph_ninja@lemmy.world 15 points 1 month 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 1 month ago (4 children)

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

[–] stebo02@lemmy.dbzer0.com 10 points 1 month ago (1 children)

More importantly it's the electromagnetic force that keeps atoms together. Gravity only keeps planets and stars together and also solar systems and galaxies, but in ordinary objects it's totally negligible.

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[–] MonkderVierte@lemmy.ml 4 points 1 month ago

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

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[–] FatsoJackson@lemmy.ml 15 points 1 month ago (1 children)

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

[–] zod000@lemmy.ml 12 points 1 month ago

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

[–] OddButNotReally@lemmy.world 15 points 1 month 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

[–] MoonMelon@lemmy.ml 11 points 1 month 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 1 month 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 1 month 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 1 month ago

Should have watched Tom Scott

[–] some_guy@lemmy.sdf.org 7 points 1 month ago (2 children)

Wow, I never thought about that.

[–] ksigley@lemm.ee 7 points 1 month 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

[–] witty_username@feddit.nl 7 points 1 month ago

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

[–] peteypete420@sh.itjust.works 6 points 1 month 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.

[–] RabbitBBQ@lemmy.world 5 points 1 month 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 1 month 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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[–] Faydaikin@beehaw.org 5 points 1 month ago (1 children)

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

[–] Codeviper828@lemmus.org 4 points 1 month ago* (last edited 1 month 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

[–] callouscomic@lemm.ee 4 points 1 month ago* (last edited 1 month ago) (5 children)

Also ghosts likely wouldn't be affected by a gravitational pull, so the concept doesn't make sense and there's just be a trail of ghosts in space.

[–] four@lemmy.zip 7 points 1 month ago

Can't they just float and follow the Earth? Or would it be too fast? What's the terminal velocity of a ghost?

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[–] Pilferjinx@lemmy.world 4 points 1 month ago (1 children)

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

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