You must log in or # to comment.
Well, since no one bothered to create a savepoint, we can’t travel back in time anyway.
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).
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)
Futurama has an episode like that. It was a pretty good one.
But what if the absence of the atoms of your body affects how the universe collapses and in turn expands?
then you’re in for a fun surprise
If you’ve already done six impossible things today, why not stop for breakfast at Milliways?
If the universe is cyclic, then the version of you from the previous one is also jumping to a time before when you left. It works if the board gets reset to the exact same position and true randomness doesn’t exist. We’re talking down to the electron scatter of radioactive decay.
If the universe is cyclic, then that would define it as a closed loop without any energy being removed or added. The very first instance of yourself traveling through time would break the loop by removing themselves from their iteration of the universe and reinsert into a future iteration. During those two points, the universe would now function with a deficit. This deficit could affect how it cycles to subsequent iterations.
What if that discrepancy in energy affects when the universe starts to contract or it’s speed to the big crunch/bang and subsequently the time to, and speed of expansion. Maybe it could even prevent the big crunch from reaching critical mass, where it would normally trigger a big bang, and stop the cycle altogether.
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?
I’m traveling forward in time right now.
Big, if true
Me too! What’s your destination?
Stable employment hopefully
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/
think this was in Issaacc Assimovv’s Robot Visions
Use a space time machine. Problem solved.
You need to add dimensions and relativity.
Don’t look at me. I’m too lazy.
Don’t worry, it has already been done. https://en.wikipedia.org/wiki/TARDIS
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
Can you detect rotational velocity using gravity?
Earth rotates at about 460m/s around it’s own axis.
and I’m sure scientists have access to a more precise number than that.
we dont have to detect what we can calculate
We have a machine that can track planets through time and space and you only want it to work on Earth?!?
Why would it only work on earth? How do you think we took close up pictures of pluto?
It would only work on earth because we’ve only given the time/space machine information about the rotation of the earth.
But my question is more about science theory than fiction. Does observing gravity give any information about how fast that mass is rotating?
“It would only work on earth because we’ve only given the time/space machine information about the rotation of the earth.”
So you’re the one that only wants it to work on earth then.
And no. “Observing” Gravity does not give any information of how fast an object is spinning around it’s own axis.
So you’re the one that only wants it to work on earth then.
No. Are you suggesting we supply this machine with the rotational velocity of all planets in the known universe? Or some other solution?
How could we jump to a planet on the other side of the galaxy?
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.
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.
What is time, if not curvy space?
So you’re saying that, if you’re traveling in space it seems like you could travel in time at the same space.
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
Time and Relative Dimension in Space, you say?
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. :-)
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.
And this is why you need the spice melange
You’d also need to solve time travel.
Eh, let’s cross that bridge when we get to it
You’d just send a drone back, to say 100 years ago, first 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.
But by the time you have collected and evaluated all the drone data you and all the masses around you would already be in a totally different configuration, making the data useless.
But maybe a little jump to the time when you sent the drone out would be easier and then you could use the drone’s data.
Someone should build a space machine so we can travel through space freely
We are all space machines on this blessed day
Blessed be
🤯
did you travel millions of years into the past?
deleted by creator
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!
Nah. Location is relative.
the question is, what’s your frame of reference? if it’s the earth you’re good. if it’s the sun, you could presumably move forward any integer number of years because earth would be in the same place in its orbit relative to the sun (but try to move forward by a year and a day and you may have a bit of a chilling discovery about orbital mechanics). however, the position of our solar system (which, you’ll remember, includes the earth, the sun, me and presumably also you) is not static relative to the rest of the universe so if that’s your frame of reference then you’ll have to move in space and time instantaneously in order to move forward in time but seem stable in space to an observer whose frame of reference is the earth.
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.
I prefer the H.G. Wells The Time Machine style,l of time travel , 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.
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.
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.
Still in my top 5. I think the acting is better than most science fiction blockbusters and every science fiction series.
Great movie. I enjoyed the lofi feel of Primer as it handled a really fun concept.
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
Same as “7 days”, they had to take the location shift into consideration.
It’s a shame we never invented a Space-Time machine
I honestly think this would not happen because you would be time-travelling in the Earth’s frame of reference
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.
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.
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
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.
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
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.
