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 to. This suggests that a time machine ought to let you move through space as well as time
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).
I’m traveling forward in time right now.
Big, if true
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.
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: https://www.pbs.org/video/pbs-space-time-speed-light-not-about-light/
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.
Imagine building the first receiver, and immediately have 20 people spawn within the same space
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: https://www.goodreads.com/en/book/show/41160292
Wow, I did not expect to find a fellow Ted Chiang enjoyer. The Merchant and the Alchemist’s Gate is one of my favorite.
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.
Someone should build a space machine so we can travel through space freely
🤯
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
Use a space time machine. Problem solved.
Jokes on you, space doesn’t exist
I suppose you’re going to tell me that the earth is flat too…
Why would you time travel to a position relative to anything other than the earth?
Ooh, new science fiction idea. We built a time machine and can only use it to reach other star systems. But just those that have been or will be at the same “spot” as earth.
With the reference point being a black hole at the center of the milky way from which it derives all it’s power, love it: get a draft to my desk before July 19th and we’ll talk potential remuneration.
If you use the CMB for reference you should be able to reach other galaxies.
This. It would have to be set as relative to something, why you would define that as any object not Earth or on Earth is a mystery to me
This is why you have to calibrate your time machine to track the relative gravity well.
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.
did you travel millions of years into the past?
That’s what bugged me about this meme: as @Turun@feddit.de points out above, you’d have to travel billions of years into the past in order to wind up that far away. Nobody using a time machine would have any reason to do that, unless it was part of some fiendish plot against humanity, à la the Temporal Cold War from Star Trek: Enterprise. We should all demand more accuracy in our science memes.
Actually for me the conclusion from my math was that it’s surprisingly possible to get millions of light years away from earth with just time travel. As such I consider the meme to be scientifically accurate.
Seeing earth as a lava planet or the primordial soup of life would be pretty sick!
Definitely a totally valid read! I try to indulge my pedantic impulses without being too obnoxious. And I didn’t mean to imply that you were also being critical of the meme.
Well, since no one bothered to create a savepoint, we can’t travel back in time anyway.
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.
I once saw a short film where this was taken into account: they moved back in time a few hours and ended you a few miles away too