A time machine would necessarily need to have some way of defining what reference frame one is stationary in space relative towards, because there is no universal frame that everything moves relative too. This suggests that a time machine ought to let you move through space as well as time
space
Submitted 8 months ago by fossilesque@mander.xyz to science_memes@mander.xyz
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CarbonIceDragon@pawb.social 8 months ago
essteeyou@lemmy.world 8 months ago
So to travel into the future and be in the “same place” relative to your planet you’d need to solve the n-body problem for at least your local system to a suitable length of time. A slight error might mean you appear inside the planet or in outer space.
Or maybe I don’t understand this stuff. :-)
Semi_Hemi_Demigod@lemmy.world 8 months ago
Mass bends spacetime so one could assert that a time machine could anchor itself to a sufficiently large mass, just like how things in orbit are still bound to the earth’s mass.
Zorque@kbin.social 8 months ago
You'd also need to solve time travel.
akilou@sh.itjust.works 8 months ago
And this is why you need the spice melange
SomeGuy69@lemmy.world 8 months ago
You’d just send a drone back to say 100 years for instance and have it send you exact coordinates into the future.
Time paradox aside you’d probably have this data already, with all alternatives and can correctly time jump right away.
ForgetPrimacy@lemmygrad.ml 8 months ago
Time and Relative Dimension in Space, you say?
gmtom@lemmy.world 8 months ago
Since relativity tells us there is no universal reference frame, then it having its reference tied to earth is perfectly valid.
Also sidenote: my favourite idea about time travel is that time travel is entirely possible, but will never be invented, because the timeline where its not invented is the only stable timeline. Because any timeline where it IS invented gets changed as soon as you use it, meaning the timeline changes over and over again every time time travel is invented repeatedly either infinitely or until someone accidentally creates a timeline where its never invented, only then does the timeline stop changing and we can actually experience it. So because we exist and can experience time, we can deduce that we will never invent time travel.
1rre@discuss.tchncs.de 8 months ago
There can be stable timelines with time travel - there’s actually 3 states:
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Perpetual instability, where the timeline changes each time the time machine is used but never reaches the same state twice
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Perpetual cyclic stability, where people’s actions in modifying the timeline lead to it eventually reaching the same state, eg. you go back in time to kill someone who becomes evil and oppresses you but the near death experience leads them capture you, so you can’t time travel any more, and to blame your people and start oppressing them, leading to the same actions
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Stability without time travel, which is the default state but incredibly hard to get once time travel is invented as with nobody to stop time travel being invented it would probably get invented again, however parts of a cyclically stable timeline could have nobody having access to time travel, but any actions by time travellers to stop time travel would likely lead to the second rather than third option
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Psythik@lemmy.world 8 months ago
Yeah I think we don’t have to worry about it for the same reason why you don’t have to worry about getting thrown backwards when jumping in a moving train.
voracitude@lemmy.world 8 months ago
Sure, but it’s a lot of fun to think about :D
Turun@feddit.de 8 months ago
Rotational reference frames are out though! (Unless you want to deal with magic forces acting on your masses)
And since the earth rotates around itself and the sun, and the sun rotates around the center of the galaxy, you will always have to deal with a moving target.
Opafi@feddit.de 8 months ago
Since I stay on earth now when I’m moving forward in time why wouldn’t I stay on earth when I move backward through time?
voracitude@lemmy.world 8 months ago
How much do you know about the “double slit” experiment and its subsequent variations? Because I think that’s a rabbithole you’ll enjoy. That first video is really just context; this next link is another video in that series, and this is the one that really pertains to the consequences of time travel: piped.video/watch?v=8ORLN_KwAgs
Sam_Bass@lemmy.world 8 months ago
You migjt have better luck and accuracy using our galaxy’ black hole for reference marker dependinh on how much time you intend to traverse
davidgro@lemmy.world 8 months ago
In most media time machines are also teleporters - many are explicitly so, with the destination space needing to be chosen at the same time as the destination time, but even when that’s not shown they still make the time traveller suddenly vanish and then just suddenly reappear elsewhen.
One movie I’ve seen with a more “realistic” time machine is Primer. It’s not at all a teleporter or portal. Very slight spoiler:
It sidesteps the whole issue that OP presents because the place where you exit the machine after traveling is just where the machine is when it’s turned on to begin with. You can’t time travel outside the machine, including to before it exists, and your path (in all four dimensions) is contiguous.
dgriffith@aussie.zone 8 months ago
I prefer the H.G. Wells style, where you affect the flow of time instead of a discontinuous jump.
You’re still attached to your current location, things just happen faster (in forwards or reverse). It also means that time travel takes time, which can be a handy plot tool.
Barbarian@sh.itjust.works 8 months ago
Primer is one of my favourite movies ever. It was made on a budget of 3 peanuts and pocket lint, and it shows, but damn it’s an interesting premise.
FlaminGoku@reddthat.com 8 months ago
Great movie. I enjoyed the lofi feel of Primer as it handled a really fun concept.
perviouslyiner@lemmy.world 8 months ago
Same with The End of Eternity - they can travel to different times at which the machine existed.
In fact, isn’t it a bit similar with the only ‘real’ possibility of time travel - you create a wormhole and age one end by moving it faster than the other end, but the only possible travel is between the two ends that you have created.
Alexstarfire@lemmy.world 8 months ago
Guess this is why the TARDIS had to be a space ship as well.
lingh0e@sh.itjust.works 8 months ago
The name TARDIS is literally the solution, “Time And Relative Dimension In Space”.
Ephera@lemmy.ml 8 months ago
Well, since this was posted in Science Memes, I’ll be so pedantic that science does not support the idea of travelling back in time.
It does support travelling forwards in time, at various speeds, but you’ll constantly be aware of where you are (even if one method involves travelling really fast and therefore may still leave you in empty space).
deo@lemmy.dbzer0.com 8 months ago
I’m traveling forward in time right now.
GBU_28@lemm.ee 8 months ago
Big, if true
Utter_Karate@hexbear.net 8 months ago
Me too! What’s your destination?
affiliate@lemmy.world 8 months ago
if you believe in the notion that the universe is cyclic then you can mimic time traveling backwards by traveling forwards, past the end of the universe, and stopping at just the right time in the new universe.
e.g., to get to 1700 you’d go (present time) -> (death of the universe) -> (1700 in next universe)
EtherWhack@lemmy.world 8 months ago
But what if the absence of the atoms of your body affects how the universe collapses and in turn expands?
Ephera@lemmy.ml 8 months ago
I mean, personally, I actually don’t believe that the Big Bang created everything out of
thin airvacuum, because much like travelling backwards in time, that would break causality.It makes much more sense for everything to just have always existed and the Big Bang is merely a very visible event + expansion afterwards.
I’m open to the notion that expansion and contraction happen in some sort of cycle, because well, many things do.But for it to be cyclical to the point where it repeats precisely the same? Why?
Can’t we just let the universe flobber on its merry way without assigning some higher meaning to everything it does?Azteh@lemmy.world 8 months ago
Futurama has an episode like that. It was a pretty good one.
bjoern_tantau@swg-empire.de 8 months ago
I thought it was possible in relativity if only you could solve that pesky going faster than light problem. Only going to the speed of light is impossible. If you were to start out beyond the speed of light you should be traveling backwards in time. Mathematically that should be possible.
Ephera@lemmy.ml 8 months ago
I have heard that notion before, but don’t know how the maths is supposed to work.
I can tell you, though, that light would be going faster than light, if it could.
Here’s a simple equation you probably know:
F = m * a
(F is force, m is mass, a is acceleration)Well, if you rearrange it, you get this:
a = F / mWe currently believe photons to have no mass.
Insert that into the equation and you get a division by zero, but our closest approximation means acceleration is infinite, as soon as any non-zero force is applied.Infinite acceleration results in immediate infinite velocity. It makes no sense for light to only accelerate until 300,000 km/s and then take its foot off the gas pedal.
This is why it’s instead believed that there is a speed limit to causality itself.
The speed of light (as well as of gravitational waves and other massless things) just happens to be the same value, because they’re going as fast as is possible.Here’s a video about the speed of causality: pbs.org/…/pbs-space-time-speed-light-not-about-li…
Etterra@lemmy.world 8 months ago
Time machines have been invented dozens of times since the 1800s; there’s s trail of them drifting through deep space.
morrowind@lemmy.ml 8 months ago
I feel like the scientists smart enough to invent time machines would have thought of that
XxXxZzZz@sh.itjust.works 8 months ago
[deleted]ILikeBoobies@lemmy.ca 8 months ago
What if I think of it as a pancake?
Actually it was my work in the field of pancake time that brought about widespread internet ridicule
JasonDJ@lemmy.zip 8 months ago
Pizza is a better example. Particularly a NYC style.
The thing about time/space travel is that you can only really travel within your cosmic neighborhood, or “slice”. You can move linearly across the surface, but if you want to actual travel through time, you have to fold the slice.
Now, if you want to expand beyond your cosmic neighborhood, then you really gotta think more like a calzone.
nilclass@discuss.tchncs.de 8 months ago
Is there a choice of toppings? Or do I have to think about a very specific pancake?
Dalvoron@lemm.ee 8 months ago
I like the idea that time machines are like phones in that you need a receiver to pick up the signal. A consequence is that you can only travel back to the time that the machine was turned on.
nailbar@sopuli.xyz 8 months ago
Imagine building the first receiver, and immediately have 20 people spawn within the same space
Pantless_Paladin@lemmy.world 8 months ago
More like 2 million inconsiderate time tourists comming to gawk at the first reciver…
ReallyActuallyFrankenstein@lemmynsfw.com 8 months ago
Unrelatedly, you may enjoy Ted Chiang’s The Merchant and the Alchemist’s Gate, the short story.
The whole book is great if you like thought-provoking sci-fi premises I guess: www.goodreads.com/en/book/show/41160292
NominatedNemesis@reddthat.com 8 months ago
Wow, I did not expect to find a fellow Ted Chiang enjoyer. The Merchant and the Alchemist’s Gate is one of my favorite.
SuperSaiyanSwag@lemmy.zip 8 months ago
This meme format having a redemption arc is my favorite. It wasn’t super sexist, but it was just unnecessarily sexist.
fossilesque@mander.xyz 8 months ago
Rescue peepo from the nazis next.
Hyphlosion@donphan.social 8 months ago
Use a space time machine. Problem solved.
Knock_Knock_Lemmy_In@lemmy.world 8 months ago
You need to add dimensions and relativity.
pyql@lemmy.world 8 months ago
I honestly think this would not happen because you would be time-travelling in the Earth’s frame of reference
tetris11@lemmy.ml 8 months ago
Yeah, or if the time machine is genuinely a teleporter, then the invetor should at least know how to correct for drift.
emuspawn@orbiting.observer 8 months ago
I mean, it’s the space-time continuum, it’s connected! As the documentary Stargate SG-1 shows, we’re well acquainted with spatial and chronological drift over interstellar distances.
Lolman228@kbin.social 8 months ago
Jokes on you, space doesn't exist
AdrianTheFrog@lemmy.world 8 months ago
Time machines don’t exist and (as far as we know) cannot exist. Therefore, we can say they work however we want. If you can travel back in time, surely you can do that while remaining close to an arbitrary point of reference.
BmeBenji@lemm.ee 8 months ago
Someone should build a space machine so we can travel through space freely
Hobbes_Dent@lemmy.world 8 months ago
How, uh, far back in time did you want to go?
CaptnNMorgan@reddthat.com 8 months ago
I think gravity is the solution to this problem. The time machine just has to be able to lock on to the earths gravitational force from across time
D61@hexbear.net 8 months ago
I have yet to stumble across a sci-fi short story about space travelers finding an entire civilization’s worth of dead bodies floating round in space only to realize that they were all time travelers who only got part of the time traveling math correct. They figured out how to get through time but couldn’t figure out how to get through space, but since all their volunteers died, they never figured it out and just kept sending people to their doom.
FiniteBanjo@lemmy.today 8 months ago
Why would you time travel to a position relative to anything other than the earth?
xia@lemmy.sdf.org 8 months ago
I’d like to believe that mass (and then by extension the Earth) “defines” the spacetime around it as much as it distorts spacetime near it. I suspect this may even be the underlying cause for the observation of speed of light being constant in the presence of earth/solar/galactic movement.
JoYo@lemmy.ml 8 months ago
did you travel millions of years into the past?
yokonzo@lemmy.world 8 months ago
So either we would have to invent teleportation along with time travel/ have some sort of "magnet pad’ that must exist and not break at all times on earth, or its the time machine type where it just fast forwards everything around you until somehow you’re in a mall
MonkderDritte@feddit.de 8 months ago
Well, since no one bothered to create a savepoint, we can’t travel back in time anyway.
Wheaties@hexbear.net 8 months ago
think this was in Issaacc Assimovv’s Robot Visions
beebarfbadger@lemmy.world 8 months ago
Ahummm, well actually, * adjusts monocle * time travel is not possible and since nobody has invented time machines yet, neither of these scenarios would happen in reality.
Draegur@lemm.ee 8 months ago
This is why you have to calibrate your time machine to track the relative gravity well.
bastion@feddit.nl 8 months ago
Nah. Location is relative.
jherazob@beehaw.org 8 months ago
That’s why you need a T.A.R.D.I.S.
keepcarrot@hexbear.net 8 months ago
If I was writing a fiction and felt the need to address this, I would make it so where you wind up is based on the location of the time machine in the time you travel. But also I probably wouldn’t and just handwave it
danc4498@lemmy.world 8 months ago
It’s my belief that Time Machines aren’t immune to the effects of gravity. When time changes, the machine goes to the space it would be at if it was affect gravity for the whole time.
BeefPiano@lemmy.world 8 months ago
Time and space are the same thing, if you’re traveling in time it seems like you could travel in space at the same time.
themeatbridge@lemmy.world 8 months ago
Yeah but traveling in space takes time, so you can reason 5hat traveling in time takes space.
casmael@lemm.ee 8 months ago
Right so have we tried putting the Time Machine in the middle of a football field or smthn?
Khanzarate@lemmy.world 8 months ago
Which is why the deLorean was an amazing time machine, obviously.
GoodEye8@lemm.ee 8 months ago
I think that’s the joke. Media presents time travel as just inputting the date and off you go, but really you need to input time AND space because the two are interconnected.
Of course we could just imagine that all time machines somehow calculate the space itself just by knowing the current spacetime and the inputted time, but now we’re giving writers too much benefit of doubt. In most cases time travel is used as plot device and very little thought is given to how it could work.
And an interesting sidenote. This also means that teleportation is a special case of time travel and if you’ve solved time travel you’re probably also solved teleportation.
Schadrach@lemmy.sdf.org 8 months ago
Alternately since we’re Earthlings, someone designing a time machine might think it’s a good idea to automatically calculate the location using the Earth as a reference point because that’s likely to be the most common use case and doing so would prevent you from dying to the void of space if you make a tiny math error. At which point you would just need to input the destination time if the target is the same location relative to Earth.
jaybone@lemmy.world 8 months ago
I teleport two Klingons every morning and I’m still late to the staff meeting.
walter_wiggles@lemmy.nz 8 months ago
So you’re saying that, if you’re traveling in space it seems like you could travel in time at the same space.
lolcatnip@reddthat.com 8 months ago
If they were really the same thing, traveling into the past would be trivial. Greg Egan’s Orthogonal series explores the consequences of space and time actually being the same thing. You can also the the difference in formulas related to proper time, where terms for space and time have opposite signs.
pancakes@sh.itjust.works 8 months ago
What is time, if not curvy space?
Kowowow@lemmy.ca 8 months ago
Couldn’t this be solved even if they weren’t linked by just flickering in and out of phase or whatever to keep gravitationally relative with the earth