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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.
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: https://piped.video/watch?v=8ORLN_KwAgs
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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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.
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.
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?
Sure you can, but you need to adjust your position due to centrifugal forces all the time. A time machine would have to do that as well.
If a ball is flying in a straight line through space with a speed of 1m/s I can predict without much math where it will be at any point in time. In fact, if the reference frame is chosen such that the ball is stationary you don’t need any math at all, because the ball doesn’t move!
However, if you have a set of two balls orbiting each other you will always have to do math to calculate their position. I mean technically you could choose the reference frame that is rotating in sync with the balls. But still you need to do math to check that the centrifugal force, which is a real force coming from nowhere in this reference frame, exactly cancels out the gravitational pull between the two balls. Because rotating reference frames are not equivalent to each other!
I really don’t get why the time machine would have to do any calculations at all. The time machine is in this reference frame. You seem to assume that by going back through time you’d be teleporting through time, which leaves the open question of where you’d appear. However, I’d much rather assume that you’d actually be “going” through time. You wouldn’t cease to exist until you reappeared somewhere. Instead you’d be in the machine for some time until you’d get out of the machine again. That’d mean neither you nor the machine ever leave the reference frame.
This meme format having a redemption arc is my favorite. It wasn’t super sexist, but it was just unnecessarily sexist.
Rescue peepo from the nazis next.
How, uh, far back in time did you want to go?
https://astronomy.stackexchange.com/questions/33514/how-fast-are-we-moving-relative-to-the-cmb#33515
Earth moves with somewhere between 230-500km/s, long term average should be 370 km/s
https://en.m.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System
https://en.m.wikipedia.org/wiki/History_of_Earth
The solar system and earth formed 4.6 billion years ago.
https://numbat.dev/?q=370+km%2Fs+*+4.6+billion+years+->+ly⏎
That means the solar system travelled 3.45-7.67 million light-years (5.67 for the average speed) since then.
That plural form (millions of light years) is borderline, but actually not incorrect.
That’s probably the guy that offered people a few dollars and a chair to watch all of earth’s history.
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.
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’ve probably also solved teleportation.
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.
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.
Or maybe the time travel happens by warping space in the first place (since you need to somehow overcome the speed of light problems anyway). Seems like a good job for a wormhole if someone wanted to write around the space/time/motion rules.
Yeah but traveling in space takes time, so you can reason 5hat traveling in time takes space.
Right so have we tried putting the Time Machine in the middle of a football field or smthn?
Yes and that’s how we ended up with American Football. In the original timeline, it never existed.
how do i get to that timeline
You have to turn left in 1867.
I thought it was Albuquerque
That’s where you must have taken a wrong toin.
Which is why the deLorean was an amazing time machine, obviously.
What is time, if not curvy space?
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. Space and time have the same relationship to each other as real and imaginary numbers, in a fairly literal sense.
So you’re saying that, if you’re traveling in space it seems like you could travel in time at the same space.
Well, since no one bothered to create a savepoint, we can’t travel back in time anyway.
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
Since space and time are intertwined, we must travel both to achieve the desired goal
Maybe this is why Stephen Hawkings time travellor party never worked out lol
I should hope that if we had time travel landing pads, we’d have a pretty good log of maintenance times in the future.
The tough part to figure out, though, is that the more a pad is used, the more maintenance it requires, which in turn modifies the logs.
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.
I honestly think this would not happen because you would be time-travelling in the Earth’s frame of reference
Ooh, but what if the time machine came from Mars and uses that as its frame of reference?
Yeah, or if the time machine is genuinely a teleporter, then the invetor should at least know how to correct for drift.
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.
There is no space reference in time traveling only a time reference, the time traveler don’t change his start point, but the Earth and the whole solarsystem do. If you travel 6 month to the future, you are still in the point where you started, but the Earth will be on the other site of the Sun. A time machine must be a spaceship, otherwise you won’t survive. That is the error of almost all movies about time travel since H.G.Wells.
This is a huge assumption. Why is it necessary that time would not have a space reference? I’d actually say that based on relativistic physics there probably is a space reference because the dimensions are linked. I think it’s possible that the momentum of the current movement could remain constant and thus stick the time traveling device to the earth. Coming to a complete referential stop in space would require beyond immense energy and be inefficient if one only wants to travel in time
Kinda depends, doesn’t it? A travel that let’s you see glimpses of reality/earth implies you’re making smaller skips that may keep you somewhat held in place. Being able to establish a vector through time may also imply control of vectors in space.
Also, six months would likely take us farther than the other side of the sun. If we’re completely de-referenced we might be able to find a universal reference frame or some wild shit.
Being human sucks.
Perhaps designated Time Travel zones that are kept clear year round and only allow jumps of exactly one year?
Yes, but it will not work, because the whole Solar system is traveling with the rotation of our Galaxy with the speed of 251 km/s, or 7,9*10^9 km/year
If you travel 6 month to the future, you are still in the point where you started, but the Earth will be on the other site of the Sun.
Why would you remain spatially locked to the sun? The solar system is moving around the milky way. The Milky way is traveling at around 370 miles per second if we use the universe as a frame of reference. A point is both a place and a moment. Everything is moving relative to everything else. Time travel is also space travel.
That’s why you need a T.A.R.D.I.S.
This. I like that Dr who actually has had this problem in universe. I don’t recall the episode, but he went to earth and ended up at the right time, but not the right place, since you know, earth is moving.
Even if you were to use the sun as a reference we orbit the sun (relative to the position of the sun) at some incredible speeds. Time of day factors in, since we’re rotating rather fast as well. So getting the right coordinates in space for a particular day, and a particular time in a particular year, for a specific place… Well, good luck.
Which isn’t to mention the fact that we’re in a galaxy, which is moving as well, so using a point of reference outside the solar system becomes insane to try and calculate; which is what you would have to do in order to enable travel outside of our solar system with something like a TARDIS.
Guess this is why the TARDIS had to be a space ship as well.
The name TARDIS is literally the solution, “Time And Relative Dimension In Space”.
Jokes on you, space doesn’t exist
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.
When I was a kid I thought that spacetime was created by mass. I thought that if you were to ever find the end of the universe you wouldn’t be able to travel beyond because you would just create new spacetime everywhere you went.
And I thought that was scientific consensus. No idea where I got it from, though.
My view has always been that space is “round”, that there is no end of the universe because it just loops back around. Apparently this is all still unknown.
It’d be really interesting if time moves at different speeds in different bits of the galaxy, find out that none of the other solar systems have life because closer to the galactic center of someone dropped a teapot when the first life evolved on earth it still wouldn’t have hit the floor.
Of course there’s a lot of reasons this isn’t the case but I dismiss them by saying they’re all just an effect of distortion due to time variance.
Maybe we’ll get s message from voyager saying ‘arrived at a star 224 light years away, it was super quick because there’s no time in the middle so you just skip that bit’
Similar to a solar system’s habitable zone there exists (or is suspected to exist) a galactic habitable zone. I think because of cosmic rays and radiation. So I guess most habitable planets would have more or less the same time dilation.
Time machines have been invented dozens of times since the 1800s; there’s s trail of them drifting through deep space.
I feel like the scientists smart enough to invent time machines would have thought of that
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.
Hence how the artist was able to choose that the time machine in this context rewinds time while conserving the universal position(?)… Relative to the center of the universe(??)… assuming eucledian space(???)
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.
