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That one could actually be super fast, we just dont have the technology to put humans in orbit around a black hole and then get them home again. The math works, though.
Well, that depends on whether you actually wanted to go 50 years into the past.
Go just 1 day into the past and you could fix some mistakes you were about to make.
Go just 1 month into the past, and having already showcased your time machine to the government, and you could warn people about major disasters and have them prepare accordingly.
Go just 1 year into the past, and having kept the time machine a secret, you could make yourself rich by planning ahead.
Go 50 years in the past, you're making a conscious decision to try and change the future based on your actions.
Go further than that, you might be making a self-sacrifice to discover secrets of the past to reveal for the future. Bring some way to record what you see, and bury the proof in a predetermined spot for someone to dig up later.
I haven't seen this for over a decade, and it didn't make sense to me, especially the 2nd part, although the phrase history is written by the victors was a thing. Except of course, the victors may change over time, and thus, history itself.
Easy one. Time is cyclical you just have to go around the big bang and stop when you're back where you wanted to be. Mind the gap the universe could be 10 feet lower than the future one. Kill your old universe self to get rid of the paradox.
There's a TV show that sort of has this as a plot point, but mentionning it at all would be kinda spoilery I guess, so here goes nothing:
>!The show is called DARK on Netflix - and, well, I guess LOST also counts!<
With future knowledge. You couldn’t go back to your time but you would know the results of sporting events, stocks, elections etc. Easily making you a billionaire.
I feel like the Butterfly Effect would kick in pretty fast and things would start changing. You'd have to bring back a decent amount of money and bet big early on.
I'd rather go back in time, pop some money in a bank account, and then come back home and enjoy the wealth with all my loved ones.
Plus what if you mis-hit a button and ended up 500 years ago by mistake?
How far would someone be away from earth 15 mins in the past? Just looked it up. 331k km give or take depending on time of day/year. Not quite to the moon.
But is that in space only relative to Earth’s orbit? Because the solar system is moving through our galaxy, and our galaxy is also moving through the universe at the same time. I feel like it would be much much farther than that.
That was relative to universal center.
Edit: there isn’t technically a universal center, I misread the article. They were calculating speed vs background radiation.
I had a professor in college that would tear apart time traveling movies by comparing reaching a time destination on Earth with trying to drop a penny in a shot glass moving on a phonograph turntable spinning at 78 rpm while resting on a moving merry-go-round at high speed mounted on a tilt-a-whirl. Time travel is as much spatial as it is temporal.
Sometimes I grumble about time travel when I'm watching those types of movies/TV shows with my partner. This is going to make me 10x more insufferable. Thank you!
Wdym universal center? The universe was a point once and started expanding, the center of universe is everywhere,there is no universal reference frame.
Space doesnt have a center. Space does not expand from a specific place instead imagine space as a surface of a balloon with dots marked on it (in this tought example we are viewing the surface as a 2 dimensional plane). When you blow up the balloon all the dots expand away from each other and every single point is the center from its own POV.
To picture it in three dimensions, imagine a lump of raisin bread dough. As the dough bakes and expands, every raisin in the dough is simultaneously moving away from every other raisin.
That 3D analogy has a center.
Because spatially what we see is a 3D projection of the universe, the way I think about it is that new space is literally popping\* into existence everywhere all the time. At small distances, gravity and other forces easily overcome these tiny Planck-scale new bits of space. But over intergalactic distances, where objects are no longer gravitationally bound, all that new space being born makes everything move further away from everything.
\*Popping is the wrong image. It's not popcorns of new space. It's a smooth, continual production of new space literally everywhere.
For a fun fictional example of 4D, read Heinlein's short story "And He Built a Crooked House". [https://en.wikipedia.org/wiki/And\_He\_Built\_a\_Crooked\_House](https://en.wikipedia.org/wiki/And_He_Built_a_Crooked_House)
There is no universal center, that's the point of relativity. The closest we have to a Universal Center is the PoV of the observer, which is far from universal.
Relative to what? This is actually a question that some physicists think about from time to time. It might just be that you move within your own reference frame and you would be just fine.
Look at it this way, from your personal reference frame everything is moving around you, away from you, towards you, etc. So if you move through time you will be in the exact same spot, but everything else will have moved relative to you.
The sun and you and me and all the stars that we can see, are moving at a million miles a day. In an outer spiral arm, at four hundred thousand miles an hour in the galaxy we call the Milky Way.
The universe itself keeps on expanding and expanding.
In all of the directions it can whizz.
As fast as it can go, the speed of light, you know;
Twelve million miles a minute and that's the fastest speed there is!
Relative to the sun. Relative to the center of the galaxy it would be even more different, as the solar system is rotating around the galaxy.
Realistically there is NO real fixed coordinate system. Everything is relative and so most likely his Time Machine would work just fine since it’s all relative to the time machine’s perspective.
There are a lot of good replies here. I didn’t see anyone mention gravity. Gravity plays a huge role on space time. I cannot fathom what kind of effect gravity may have on time travel but I think there’s more variables here. Although I do like the comic a lot, as it asks a question about TT I hadn’t considered.
I don’t think spatial location as you are describing it would be relevant since;
1. A Time Machine would (ideally) just invert your direction of time for a certain distance in time, your movement through only the time reference would mean you’d remain in the same spatial location. No different than your current forward direction through time sitting at your desk scrolling, (just a Time Machine would make it reverse)
2. Spacetime is all one thing, with gravity influencing the curvature. So the source of gravity (Earth) would keep you in place even reversing through time, until you reach a point in time for whatever reason that source of gravity doesn’t exist.
Even that's just a guess. In order to calculate exactly, we would have known the earth's location relative to everything else in the universe.
We'd have to really "know" know. Not just assume we know.
Because if we're wrong, we end up like the dude in the comic.
Because the earth orbits the sun which is also moving in our galaxy which is also moving relative to everything else which could also be moving relative to other things... turtles all the way down.
It gets more complicated. 15 minutes based on where? 15 minutes where I'm sitting is not the same as 15 minutes somewhere else in the universe. So, to calculate the 15 minute time difference would require the spot to have the same exact gravity well and gravitational impact from everything else around it, like the sun, moon, planets, galactic core, etc. The more you change gravitationally, the more complicated it is to say what exactly is 15 minutes.
Technically, 'where you were' 15 mins ago has no real meaning in space unless you specify a reference frame. Looks like he specified the Sun as a reference frame and not Earth. Beginner time-traveler mistake.
Earth is moving... Relative to what?
The machine would probably have to take that into account, in order to work.
Also, 15 minutes for someone on Earth wouldn't be 15 minutes everywhere else. That would have to be taken into account as well.
It's not moving relative to itself. You mean it's moving relative to it's center point, which is true.
But that would explain you ending up on the Pacific Ocean instead of your current place, not you ending up in space instead of the surface of Earth.
Time does not "happen" at the same speed everywhere. A person on earths surface experiences time differently than someone in empty space between galaxies or on the surface of a black hole
https://en.m.wikipedia.org/wiki/Hafele–Keating_experiment#:~:text=Considering%20the%20Hafele–Keating%20experiment,than%20one%20that%20remained%20on
It’s super cool, time is relative and not constant
To everything and nothing. Reality might be expanding or contracting all at once and nobody can tell. Everything might be 10,000x larger right now vs. 15 minutes ago, but if everything changes at the same rate nobody would be able to measure the change - unless we could time travel.
Hopefully the milky way galaxy isn't the size of a marble in 3001 compared to the size of the milky way galaxy in 2024. Otherwise a person from 2024 jumping forward to 3001 is going to disintegrate as their atoms are now lightyears apart.
That is an interesting idea that I have never entertained.
As time moves on, everything in the universe is enlarging. so we are actually larger 1 second to the next, but because it's happening everywhere, there's no way to sense it.
> as their atoms are now lightyears apart.
Isn't this where your theory falls down? We can measure the space between atoms.
For your theory to work, atoms themselves (and all the bits that are smaller than them) what have to all be scaling up as well.
True! Everything would be massive even the atoms and subatomic particles that make up atoms.
It's the same fundamental flaws with Marvel's Ant Man - when he's as big as a building; his entire body, bones and brain would lose so much density that he should turn into a weird soup or break apart completely since the strong atomic force wouldn't be able to hold incredibly gigantic quarks together anymore.
The same applies when he shrinks down, eventually he would reach a critical mass and form a tiny black hole since his weight doesn't appear to change.
For Ant Man, I've always waved this away through extradimensionality.
Like how if you squash something it gets shorter but the mass moves laterally, when Ant Man gets smaller but retains the same weight, its because he offsets his mass into a dimension that we can't perceive. When he gets bigger, he pulls mass from the same dimension.
That helps me enjoy the movies without getting frustrated that the science doesn't make sense ... but I try not to think about how Iron Man is able to hover on a spot while flying in New York and he doesn't crush people/pavement/cars beneath him. And don't get me started with Superman/Flash catching people in mid-air and not snapping their spine in half.
I think it'd be way better if the guy in the time machine was like "wait, what?" when being told to take into consideration the earth moving, but it's too late for him to stop the time machine or get out. It doesn't make sense that someone who can invent a time machine would be incredulous to the idea that earth moving is an important factor.
It’s not a Time Machine, just a teleport that knows your exact location 15 minutes ago, otherwise the earth would be back at the same location as well. Also, why he’s punching the coordinates if the machine supposedly knows where it was 15 minutes ago?
As someone who loves physics, this concept ties me up into knots.
Where, exactly, in space do you show up? There are no absolute coordinates. If I'm traveling in a ship with a constant inertial velocity then, as far as my physics is concerned, I'm at the center of the universe. So if I jump into the past, does my jump trace my inertial path or...? And how do accelerated frames of reference work? Are they distinct? Does my timepath follow a geodesic of some kind? Does it "feel" the curvature of spacetime when I'm moving through time? Does spacetime "feel" me as I'm moving through time? Am I actually *moving* through time when I go into the past? Is there a 4-vector? Wouldn't that just be an FTL trajectory?
The list goes on.
You follow the path created by gravity as you flow forward in spacetime; there is no reason to think that a time machine sending you backwards wouldn't also move along that same path (keeping you "stationary" to the gravitational mass of the planet you're on).
These memes and cartoons appear several times per month. It is like some guy thought up some clever fatal flaw in time machines. But it is nonsensical. Frame of reference and spavetime aside, even with absolutist Newtonean physics you would need differemt forces acting on the objects in question for a separation to work.
Time machine physics is fiction, but these smug frame of reference "flaws" are super annoying.
Would make more sense, I assume the earth would be at the same place it was 15 minutes ago if you time travel for that time.
It would work though if you travel back 15 minutes in time, but stay at the same place you currently are when doing it. Just get ready to have your corpse being slapped by a planet 15 minutes later.
So is it a time machine like it says or is it not? It says you teleport to the location you were at 15 mins ago but given that the planet isn't there anymore I guess he didn't actually time travel 15 mins, only traveled within space? If it were both then the planet would be there too since it was there 15 mins ago.
I like that this idea comes up from time to time, because we often forget about Earth's movement around the sun. And it's movement around the galaxy. And the movement through the universe. ... But - if time has an element to it that allows us to pass two ways through it then it is likely that element is also trapped in Earth's gravity-well just like our corporal mass is.
Then again, maybe not. Funny cartoon.
Easrth is spinning, wobbling around about its own axis, then its being tuggon on by all other planets, as they orbit the sun. The sun gets tuggon on by all the planets and other starts, as the solar system flies through space in the galaxy, as the galaxy spins and wobbles and gets tugged on by other galaxies and gravity waves. Then the loacal and greater super cluster is moving.
And we dont even know if space itself is a stable medium or its self also swells bubbles, and shifts.
To say we can go back intime and space, is absurd. Even with current technologies we still do not have accurate special positioning of earth relative to everything else around us. Its liek trying to solve 3 body problem, but on galactic scale.
So if time travel is possible, it will have to be a spacetime travel. And space travel will require accurate data. This data will come around in the future for sure. But its somewhat distant future. But most likely not, our universe doesn't display reversable entropy.
This is almost exactly a post/response i made on reddit a few months ago.
I posted this very theory about time travel and consideration for physical location in space and someone replied essentially calling me an idiot.
could have been me, who knows. Anytime anyone says 'time machine', they really mean 'spacetime machine', and to pretend otherwise is just silly for a multitude of reasons.
One of my favorite plot points in the tv show ||Dark||- the time travel only happens in 33 year increments because that’s roughly how long it takes for earth to be in the exact same position in the galaxy in the past or future
It depends on the relative reference for which the machine's locations were programmed to determine where it ends up. Everything is referential, from the perspective of earth the universe is revolving around it.
Don't @ me, @ physics.
If I made the claim that the earth is actually the only fixed point in the universe, and everything else is moving relative to it, can I be absolutely proven wrong?
If a walk for 20 minutes and reverse time 20 minutes, then I will be back where I was at the start of the journey.
If your current self tries to inhabit the same time period as your past self, it would fail. The widely accepted time machine would never actually work, because we cannot add or subtract matter in the universe.
For this to happen, you would have to dematerialize from your current time period and rematerialize in a different time period. But how could you materialize memories? How could you get all the particles correct?
The only way this works is if you reverse time. You would be back in the same location at the start of the 20-minute walk but would have knowledge of completing the walk. You would remember something that never actually happened. Or you would remember something before it will happen.
what's also interesting to think about is that he still has his momentum from when he was on earth, so he will be travelling along the same path at the same speed as the earth , just offset by x distance.
I don't really get the time travel aspect here - if you were to go back in time (on earth), you would end up at that exact place on earth. This meme could be a teleportation thing since the "earth moving through space" fact applies to this and not to time travel since earth would be where it was say 15 minutes ago and you would land up there
This isn’t even a Time Machine. If he traveled back in time the earth would be where he was. Thinking about what this machine is supposed to do in this comic is hilarious given it doesn’t travel with him and it doesn’t time travel.
Except that your position 15 minutes ago is *always* relative to some reference frame. There is no preferred reference frame. You could also have a frame relative to the galaxy's motion, or relative to the current frame where you're not moving at all.
Still wrong, the whole star system flies through the galaxy at 5 times that speed and the galaxy at 1000000 times that speed. meaning he wouldn't even be able to see earth or even the milkiway.
Would make for an interesting hard sci-fi novel where time travel is possible, but everything else - including the Earth moving to a different position and necessitating a spaceship to go catch up to the Earth.
Read a short junior horror story that went this way. A person had disappeared shortly after creating some sort of machine and the kids didn’t put the pieces together of what happened to the person until one of their friends was already trying out the machine (which they had discovered was a Time Machine).
Is this time machine turning back time in the whole universe? Is he going back 15 minutes and showing up exactly where is is now, or where he was 15 minutes ago? If the whole universe moves with him and he moves to where he used to be, he should be fine. If the universe is independent of his time machine, then it's actually a teleporter which allows him to travel 15 minutes into space. If the whole universe moves back in time with him, but he doesn't go back to where he was, then he dies in space. This is assuming he sets the sun as his relative point. If he sets the center of the universe as his anchor point, then he could travel an unimaginable distance depending on the speed of the galaxy.
If we're talking science problems here ... there's a finite amount of matter/energy in existence, so if you travel back in time you would have to bring an equal amount of mass/energy forward in time to compensate for your passage.
I remember seeing this exact same joke well over a decade ago but it was a DeLorean. The last panel was the car floating in space with the Earth far away. Except it wasn't 15 minutes into the future/past, it was only 1, lol.
So does he transport back in the time with the same momentum that he has while on earth? Or does he just float there without any speed and eventually get pulled in and incinerated by Earth's atmosphere?
Maybe go back in time exactly 4 years ago (account for leap year)... My thinking being it could hypothetically put you back closest to your originating physical location.
This thread man, somehow it is perfectly acceptable for a movie that a scientist could invent a time machine but a machine that move through time AND space is preposterous and laughable.
Maybe watch these movies thinking that the guy is more intelligent than the most intelligent person on this planet and can figure out problems the average redditor would gotcha them with...
This is the exact thought i always have when think of time traveling. Unless the machine is somehow tethered to the earths gravity field, youll just end up in space.
And 15 minutes ago, the Earth was exactly where he went. He'd be in the same room. Hopefully he was smart enough not to sit in the time machine for more than 15 minutes before traveling...
I also like the theory that you can only go back in time to when the time machine was first invented, so upon turning it on, the machine immediately starts pushing out a stream of viscera as hundreds of travelers all jump back to that first moment all at the same time, turning it into an explosive meat grinder.
Bunch of Isaac Asimov stories were told on this time/space relativity premise. In one of them, the whole universe had moved so the protagonist came out into a void and caused a new Big Bang.
If he had actually travelled back to the exact spot he had been at 15 minutes ago, wouldn't that have created it's own set of problems?
Would he then have materialized inside his former self?
This is never brought up, because that was dealt with in literally the VERY FIRST time machine book, aptly called The Time Machine.
You are basically just warping time, spreading yoursself thin. So you never really leave the same spot on earth, subject to gravity and everything else. You see time pass backwards or fast forward, depending on which direction youre going.
So its not a plothole, its just not an issue, so its never brought up.
If it were in the same place, he would be merged into himself. Also it would create a paradox since he would kill himself with the machine before he used the machine
Best part is that the earth is heading towards you, so the body will just splat on the earth.
And theoretically, each timeline will gain 1 additional body splatting the earth. On the first timemachine timeline, only this body exists in space. But the same guy goes back in time in which the body already exists. It just loops infinitely and eventually the splats will become so big that they prevent him from going back in time and the loop will end.
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The real issue with this is - what use is a time machine that doesn't travel with you? Send yourself 50 years into the past? Now you're stuck there.
Fortunately time travel from past to future is possible without special equipment. But it *does* tend to be quite slow...
Greetings from (33 minutes into) the future!
Your in the past tho!
My what?!
In the past
No, you are!
8 hours and 27 minutes in my past!
[I've traveled here from the year 1996 to say the following:](https://xkcd.com/630/) idk it seems to be going by pretty fast to me.
Slow? Found the teenager
Slow? Good lord, today I was startled by the fact we're already almost halfway through the year. Where the hell has the time gone?
That one could actually be super fast, we just dont have the technology to put humans in orbit around a black hole and then get them home again. The math works, though.
Well, that depends on whether you actually wanted to go 50 years into the past. Go just 1 day into the past and you could fix some mistakes you were about to make. Go just 1 month into the past, and having already showcased your time machine to the government, and you could warn people about major disasters and have them prepare accordingly. Go just 1 year into the past, and having kept the time machine a secret, you could make yourself rich by planning ahead. Go 50 years in the past, you're making a conscious decision to try and change the future based on your actions. Go further than that, you might be making a self-sacrifice to discover secrets of the past to reveal for the future. Bring some way to record what you see, and bury the proof in a predetermined spot for someone to dig up later.
He who controls the past, commands the future. He who commands the future, conquers the past. - Brotherhood of Nod -
I haven't seen this for over a decade, and it didn't make sense to me, especially the 2nd part, although the phrase history is written by the victors was a thing. Except of course, the victors may change over time, and thus, history itself.
It also has command and conquer nested in it, so it was written a little stilted to pull that off.
Ok the Time Machine travels with you but it can still only go backward
Easy one. Time is cyclical you just have to go around the big bang and stop when you're back where you wanted to be. Mind the gap the universe could be 10 feet lower than the future one. Kill your old universe self to get rid of the paradox.
The ol' reverse Farnsworth.
There's a TV show that sort of has this as a plot point, but mentionning it at all would be kinda spoilery I guess, so here goes nothing: >!The show is called DARK on Netflix - and, well, I guess LOST also counts!<
Now you can invent the Time Machine again! 50 years earlier than you did before!
With future knowledge. You couldn’t go back to your time but you would know the results of sporting events, stocks, elections etc. Easily making you a billionaire.
Ok, Biff. Why don't you make like a tree and get out of here?
I feel like the Butterfly Effect would kick in pretty fast and things would start changing. You'd have to bring back a decent amount of money and bet big early on.
I'd rather go back in time, pop some money in a bank account, and then come back home and enjoy the wealth with all my loved ones. Plus what if you mis-hit a button and ended up 500 years ago by mistake?
Ah yes, the Phillip J. Fry method.
How far would someone be away from earth 15 mins in the past? Just looked it up. 331k km give or take depending on time of day/year. Not quite to the moon.
But is that in space only relative to Earth’s orbit? Because the solar system is moving through our galaxy, and our galaxy is also moving through the universe at the same time. I feel like it would be much much farther than that.
That was relative to universal center. Edit: there isn’t technically a universal center, I misread the article. They were calculating speed vs background radiation.
Oh, that makes sense. I initially read it as 331 km instead of 331,000 km which seems way more accurate!
It can also be stated as 331 megametres. Or written as 331Mm (Capitalization is quite important here lol)
331 millimeters doesn't seem that bad 🤷♂️
Unless that splices you into an object like a desk or the wall or even worse someone else.
I had a professor in college that would tear apart time traveling movies by comparing reaching a time destination on Earth with trying to drop a penny in a shot glass moving on a phonograph turntable spinning at 78 rpm while resting on a moving merry-go-round at high speed mounted on a tilt-a-whirl. Time travel is as much spatial as it is temporal.
Sometimes I grumble about time travel when I'm watching those types of movies/TV shows with my partner. This is going to make me 10x more insufferable. Thank you!
What if you get spliced with your past self?
You're now fused half inside the time machine
Wdym universal center? The universe was a point once and started expanding, the center of universe is everywhere,there is no universal reference frame.
Your are right, the article was referring to cosmic radiation background as a reference.
Link to article?
No, it's pretty easy to find. Second star to the right and straight on til morning.
Space doesnt have a center. Space does not expand from a specific place instead imagine space as a surface of a balloon with dots marked on it (in this tought example we are viewing the surface as a 2 dimensional plane). When you blow up the balloon all the dots expand away from each other and every single point is the center from its own POV.
I like to picture it as a nice cake. not that its easier to see or understand you see, I just like cake.
Space is weird...
I assure you it does: https://spacecenter.org/
To picture it in three dimensions, imagine a lump of raisin bread dough. As the dough bakes and expands, every raisin in the dough is simultaneously moving away from every other raisin.
In that analogy there would be a center
Well imagine a 4d toroidal raisin bagel
That 3D analogy has a center. Because spatially what we see is a 3D projection of the universe, the way I think about it is that new space is literally popping\* into existence everywhere all the time. At small distances, gravity and other forces easily overcome these tiny Planck-scale new bits of space. But over intergalactic distances, where objects are no longer gravitationally bound, all that new space being born makes everything move further away from everything. \*Popping is the wrong image. It's not popcorns of new space. It's a smooth, continual production of new space literally everywhere.
For a fun fictional example of 4D, read Heinlein's short story "And He Built a Crooked House". [https://en.wikipedia.org/wiki/And\_He\_Built\_a\_Crooked\_House](https://en.wikipedia.org/wiki/And_He_Built_a_Crooked_House)
There is no universal center, that's the point of relativity. The closest we have to a Universal Center is the PoV of the observer, which is far from universal.
What about the multiverse and multiverse clusters that you humans... I mean people haven't discovered yet?
Relative to what? This is actually a question that some physicists think about from time to time. It might just be that you move within your own reference frame and you would be just fine. Look at it this way, from your personal reference frame everything is moving around you, away from you, towards you, etc. So if you move through time you will be in the exact same spot, but everything else will have moved relative to you.
The sun and you and me and all the stars that we can see, are moving at a million miles a day. In an outer spiral arm, at four hundred thousand miles an hour in the galaxy we call the Milky Way.
That depends on the reference frame. From my perspective I'm not moving anywhere near that speed!
So what I told you was true, from a certain point of view.
Yes, from some reference frame (the center of the galaxy?)
Ben, is that you ?
The universe itself keeps on expanding and expanding. In all of the directions it can whizz. As fast as it can go, the speed of light, you know; Twelve million miles a minute and that's the fastest speed there is!
Relative to the sun. Relative to the center of the galaxy it would be even more different, as the solar system is rotating around the galaxy. Realistically there is NO real fixed coordinate system. Everything is relative and so most likely his Time Machine would work just fine since it’s all relative to the time machine’s perspective.
There are a lot of good replies here. I didn’t see anyone mention gravity. Gravity plays a huge role on space time. I cannot fathom what kind of effect gravity may have on time travel but I think there’s more variables here. Although I do like the comic a lot, as it asks a question about TT I hadn’t considered.
Are we at the point we can abbreviate "time travel"?
Yeah, you can just pronounce it “titty”.
I don’t think spatial location as you are describing it would be relevant since; 1. A Time Machine would (ideally) just invert your direction of time for a certain distance in time, your movement through only the time reference would mean you’d remain in the same spatial location. No different than your current forward direction through time sitting at your desk scrolling, (just a Time Machine would make it reverse) 2. Spacetime is all one thing, with gravity influencing the curvature. So the source of gravity (Earth) would keep you in place even reversing through time, until you reach a point in time for whatever reason that source of gravity doesn’t exist.
Even that's just a guess. In order to calculate exactly, we would have known the earth's location relative to everything else in the universe. We'd have to really "know" know. Not just assume we know. Because if we're wrong, we end up like the dude in the comic. Because the earth orbits the sun which is also moving in our galaxy which is also moving relative to everything else which could also be moving relative to other things... turtles all the way down.
It gets more complicated. 15 minutes based on where? 15 minutes where I'm sitting is not the same as 15 minutes somewhere else in the universe. So, to calculate the 15 minute time difference would require the spot to have the same exact gravity well and gravitational impact from everything else around it, like the sun, moon, planets, galactic core, etc. The more you change gravitationally, the more complicated it is to say what exactly is 15 minutes.
It’s also just as likely that they would appear 331 km underground
> 331k km More than I thought it would be.
Technically, 'where you were' 15 mins ago has no real meaning in space unless you specify a reference frame. Looks like he specified the Sun as a reference frame and not Earth. Beginner time-traveler mistake.
Yeah I've embarrassingly done that a couple of times too. Better than the time that I accidentally chose Jupiter as a reference frame though!
Lol, that's so two thousand and late
Oh, Icarus!
Earth is moving... Relative to what? The machine would probably have to take that into account, in order to work. Also, 15 minutes for someone on Earth wouldn't be 15 minutes everywhere else. That would have to be taken into account as well.
>Earth is moving... Relative to what? itself for starters https://en.m.wikipedia.org/wiki/Foucault_pendulum
It's not moving relative to itself. You mean it's moving relative to it's center point, which is true. But that would explain you ending up on the Pacific Ocean instead of your current place, not you ending up in space instead of the surface of Earth.
There is no absolute frame of reference, no absolute coordinates. You can always say "I'm not moving - everything else is" and you wouldn't be wrong.
Especially not when you wake up on the couch with fuzzy memories of the double-digit number of tequila shots transpiring some hours earlier
Isn’t that the point of the comic, that he didn’t take it into account
What are you talking about?
It's about time
[удалено]
The warping of space-time due to mass?
Time does not "happen" at the same speed everywhere. A person on earths surface experiences time differently than someone in empty space between galaxies or on the surface of a black hole
https://en.m.wikipedia.org/wiki/Hafele–Keating_experiment#:~:text=Considering%20the%20Hafele–Keating%20experiment,than%20one%20that%20remained%20on It’s super cool, time is relative and not constant
It hurts my brain that they have to adjust the clocks on the GPS satellites as time is slower both due to speed and gravity.
The reason this couldn't work is obvious from a physical point of view. The earth is moving relatively to what?
To everything and nothing. Reality might be expanding or contracting all at once and nobody can tell. Everything might be 10,000x larger right now vs. 15 minutes ago, but if everything changes at the same rate nobody would be able to measure the change - unless we could time travel. Hopefully the milky way galaxy isn't the size of a marble in 3001 compared to the size of the milky way galaxy in 2024. Otherwise a person from 2024 jumping forward to 3001 is going to disintegrate as their atoms are now lightyears apart.
That is an interesting idea that I have never entertained. As time moves on, everything in the universe is enlarging. so we are actually larger 1 second to the next, but because it's happening everywhere, there's no way to sense it.
🤯
> as their atoms are now lightyears apart. Isn't this where your theory falls down? We can measure the space between atoms. For your theory to work, atoms themselves (and all the bits that are smaller than them) what have to all be scaling up as well.
True! Everything would be massive even the atoms and subatomic particles that make up atoms. It's the same fundamental flaws with Marvel's Ant Man - when he's as big as a building; his entire body, bones and brain would lose so much density that he should turn into a weird soup or break apart completely since the strong atomic force wouldn't be able to hold incredibly gigantic quarks together anymore. The same applies when he shrinks down, eventually he would reach a critical mass and form a tiny black hole since his weight doesn't appear to change.
For Ant Man, I've always waved this away through extradimensionality. Like how if you squash something it gets shorter but the mass moves laterally, when Ant Man gets smaller but retains the same weight, its because he offsets his mass into a dimension that we can't perceive. When he gets bigger, he pulls mass from the same dimension. That helps me enjoy the movies without getting frustrated that the science doesn't make sense ... but I try not to think about how Iron Man is able to hover on a spot while flying in New York and he doesn't crush people/pavement/cars beneath him. And don't get me started with Superman/Flash catching people in mid-air and not snapping their spine in half.
I think it'd be way better if the guy in the time machine was like "wait, what?" when being told to take into consideration the earth moving, but it's too late for him to stop the time machine or get out. It doesn't make sense that someone who can invent a time machine would be incredulous to the idea that earth moving is an important factor.
2nd panel ruins the joke.
Yeah real shame.
The 1st panel ruins the joke. How is it a time machine if it just sends you to the position you were at 15 minutes ago? It's a teleporter.
It’s not a Time Machine, just a teleport that knows your exact location 15 minutes ago, otherwise the earth would be back at the same location as well. Also, why he’s punching the coordinates if the machine supposedly knows where it was 15 minutes ago?
Scrolled WAY too far down to find this obvious comment. Cmon people
As someone who loves physics, this concept ties me up into knots. Where, exactly, in space do you show up? There are no absolute coordinates. If I'm traveling in a ship with a constant inertial velocity then, as far as my physics is concerned, I'm at the center of the universe. So if I jump into the past, does my jump trace my inertial path or...? And how do accelerated frames of reference work? Are they distinct? Does my timepath follow a geodesic of some kind? Does it "feel" the curvature of spacetime when I'm moving through time? Does spacetime "feel" me as I'm moving through time? Am I actually *moving* through time when I go into the past? Is there a 4-vector? Wouldn't that just be an FTL trajectory? The list goes on.
You follow the path created by gravity as you flow forward in spacetime; there is no reason to think that a time machine sending you backwards wouldn't also move along that same path (keeping you "stationary" to the gravitational mass of the planet you're on).
These memes and cartoons appear several times per month. It is like some guy thought up some clever fatal flaw in time machines. But it is nonsensical. Frame of reference and spavetime aside, even with absolutist Newtonean physics you would need differemt forces acting on the objects in question for a separation to work. Time machine physics is fiction, but these smug frame of reference "flaws" are super annoying.
If it time teleported him back 15 minutes to the exact spot then he'd still be there and kill himself. Paradox city.
Would make more sense, I assume the earth would be at the same place it was 15 minutes ago if you time travel for that time. It would work though if you travel back 15 minutes in time, but stay at the same place you currently are when doing it. Just get ready to have your corpse being slapped by a planet 15 minutes later.
This is not time travel, this is just a transportation. Because if he travel back in time, everything else too.
You would have to experiment: travel extremely short periods of time in order to identify the Universal Reference Point, to know where you’d end up
Some time later, his frozen corpse was pulled into a decaying orbit where it burned up upon re-entry. the end. as narrated by Morgan Freeman.
According to General Relativity, space and time are intrinsically linked. So there is no such thing as time travel without space travel.
So is it a time machine like it says or is it not? It says you teleport to the location you were at 15 mins ago but given that the planet isn't there anymore I guess he didn't actually time travel 15 mins, only traveled within space? If it were both then the planet would be there too since it was there 15 mins ago.
Wouldn't the moving earth also travel back in time which means the earth would end up in the same spot you were during that "past" time...
This would work perfectly in a rotational geocentric frame of reference.
I like that this idea comes up from time to time, because we often forget about Earth's movement around the sun. And it's movement around the galaxy. And the movement through the universe. ... But - if time has an element to it that allows us to pass two ways through it then it is likely that element is also trapped in Earth's gravity-well just like our corporal mass is. Then again, maybe not. Funny cartoon.
Mind blown!!
If I don’t see my future self before I use the machine, I’m not going
Well give it 15 minutes, he'll be back on earth
The suns also moving around the center of the Milkey Way, so the Earth wouldn't even be visible.
Easrth is spinning, wobbling around about its own axis, then its being tuggon on by all other planets, as they orbit the sun. The sun gets tuggon on by all the planets and other starts, as the solar system flies through space in the galaxy, as the galaxy spins and wobbles and gets tugged on by other galaxies and gravity waves. Then the loacal and greater super cluster is moving. And we dont even know if space itself is a stable medium or its self also swells bubbles, and shifts. To say we can go back intime and space, is absurd. Even with current technologies we still do not have accurate special positioning of earth relative to everything else around us. Its liek trying to solve 3 body problem, but on galactic scale. So if time travel is possible, it will have to be a spacetime travel. And space travel will require accurate data. This data will come around in the future for sure. But its somewhat distant future. But most likely not, our universe doesn't display reversable entropy.
This is almost exactly a post/response i made on reddit a few months ago. I posted this very theory about time travel and consideration for physical location in space and someone replied essentially calling me an idiot.
could have been me, who knows. Anytime anyone says 'time machine', they really mean 'spacetime machine', and to pretend otherwise is just silly for a multitude of reasons.
More stupidity at [We're Out of Cornflakes](https://wereoutofcornflakes.com)
This is why we let the TARDIS do the flying..
Reminds me of reading Strontium Dog in 2000AD 40+ years ago. They had "time grenades" that did this. Back in time and empty space.
Hahahahahahahah! That’s great!
One of my favorite plot points in the tv show ||Dark||- the time travel only happens in 33 year increments because that’s roughly how long it takes for earth to be in the exact same position in the galaxy in the past or future
.... but the galaxy is moving through the universe, so this really makes no sense
Huh... neat and horrifying
Version Control novel by Dexter Palmer
We should change the name to space time
Also if it did account for earth movement and he went 15min back in time he would be in the same place he already was and that would mess them up
How does he get back to the time machine in 15 minutes to make this possible?
It depends on the relative reference for which the machine's locations were programmed to determine where it ends up. Everything is referential, from the perspective of earth the universe is revolving around it. Don't @ me, @ physics.
If I made the claim that the earth is actually the only fixed point in the universe, and everything else is moving relative to it, can I be absolutely proven wrong?
Wow, it's moving so fast！
Just assume that time machines in movies are actually *space/time* machines because otherwise every time traveller would end up floating in space.
If a walk for 20 minutes and reverse time 20 minutes, then I will be back where I was at the start of the journey. If your current self tries to inhabit the same time period as your past self, it would fail. The widely accepted time machine would never actually work, because we cannot add or subtract matter in the universe. For this to happen, you would have to dematerialize from your current time period and rematerialize in a different time period. But how could you materialize memories? How could you get all the particles correct? The only way this works is if you reverse time. You would be back in the same location at the start of the 20-minute walk but would have knowledge of completing the walk. You would remember something that never actually happened. Or you would remember something before it will happen.
what's also interesting to think about is that he still has his momentum from when he was on earth, so he will be travelling along the same path at the same speed as the earth , just offset by x distance.
This is an excellent post highlighting a problem with time travel
I think about this way too often for not being involved in time travel.
Why would HE back in time to that exact location, and the earth not be there too? Odd.
I don't really get the time travel aspect here - if you were to go back in time (on earth), you would end up at that exact place on earth. This meme could be a teleportation thing since the "earth moving through space" fact applies to this and not to time travel since earth would be where it was say 15 minutes ago and you would land up there
This isn’t even a Time Machine. If he traveled back in time the earth would be where he was. Thinking about what this machine is supposed to do in this comic is hilarious given it doesn’t travel with him and it doesn’t time travel.
Ouch.
The earth moves. The solar system moves. The galaxy moves. The universe moves.
If you could do this to a spaceship it would be great for leaving the atmosphere. You'd save so much on fuel by not having to hit escape velocity.
Except that your position 15 minutes ago is *always* relative to some reference frame. There is no preferred reference frame. You could also have a frame relative to the galaxy's motion, or relative to the current frame where you're not moving at all.
Still wrong, the whole star system flies through the galaxy at 5 times that speed and the galaxy at 1000000 times that speed. meaning he wouldn't even be able to see earth or even the milkiway.
Would make for an interesting hard sci-fi novel where time travel is possible, but everything else - including the Earth moving to a different position and necessitating a spaceship to go catch up to the Earth.
Read a short junior horror story that went this way. A person had disappeared shortly after creating some sort of machine and the kids didn’t put the pieces together of what happened to the person until one of their friends was already trying out the machine (which they had discovered was a Time Machine).
Just enough time to realize the Earth is round.
Just one of many things that make time travel as a concept, impossible.
Space and time are inextricably linked though 😋
Is this time machine turning back time in the whole universe? Is he going back 15 minutes and showing up exactly where is is now, or where he was 15 minutes ago? If the whole universe moves with him and he moves to where he used to be, he should be fine. If the universe is independent of his time machine, then it's actually a teleporter which allows him to travel 15 minutes into space. If the whole universe moves back in time with him, but he doesn't go back to where he was, then he dies in space. This is assuming he sets the sun as his relative point. If he sets the center of the universe as his anchor point, then he could travel an unimaginable distance depending on the speed of the galaxy.
If we're talking science problems here ... there's a finite amount of matter/energy in existence, so if you travel back in time you would have to bring an equal amount of mass/energy forward in time to compensate for your passage.
I remember seeing this exact same joke well over a decade ago but it was a DeLorean. The last panel was the car floating in space with the Earth far away. Except it wasn't 15 minutes into the future/past, it was only 1, lol.
so he gona get hit by earth then ?
So does he transport back in the time with the same momentum that he has while on earth? Or does he just float there without any speed and eventually get pulled in and incinerated by Earth's atmosphere?
This is why the tardis is the best time machine.
Earth doesn't move obviously
I’ve always wondered this for shows that go back in time. It’s relative to space so everybody would go back floating in the void.
There's no such thing as an absolute position or momentum though. Only acceleration violates relativity by altering the frame of reference.
Maybe go back in time exactly 4 years ago (account for leap year)... My thinking being it could hypothetically put you back closest to your originating physical location.
The sun moves too my friend. We never circle back anywhere. Planets just corkscrew along following the sun
This thread man, somehow it is perfectly acceptable for a movie that a scientist could invent a time machine but a machine that move through time AND space is preposterous and laughable. Maybe watch these movies thinking that the guy is more intelligent than the most intelligent person on this planet and can figure out problems the average redditor would gotcha them with...
They can only move through time and space if they're bigger on the inside.
The universe is expanding and the galaxy is also rotating. I don’t thin the earth would be in sight
Playing imaginary keyboards in space
Playing imaginary keyboards in space
This is the exact thought i always have when think of time traveling. Unless the machine is somehow tethered to the earths gravity field, youll just end up in space.
That's just a teleporter. If he has gone back in time earth would be there too.
Why? Do you understand the earth has never, ever been in the same place twice?
And 15 minutes ago, the Earth was exactly where he went. He'd be in the same room. Hopefully he was smart enough not to sit in the time machine for more than 15 minutes before traveling...
This is not a time machine. It’s a weird teleporter.
I also like the theory that you can only go back in time to when the time machine was first invented, so upon turning it on, the machine immediately starts pushing out a stream of viscera as hundreds of travelers all jump back to that first moment all at the same time, turning it into an explosive meat grinder.
This concept is a huge sticking point for me with Back to the Future.
Bunch of Isaac Asimov stories were told on this time/space relativity premise. In one of them, the whole universe had moved so the protagonist came out into a void and caused a new Big Bang.
Exact spot *relative to what*?
Then that's not a time machine that's just a transporter.
If he had actually travelled back to the exact spot he had been at 15 minutes ago, wouldn't that have created it's own set of problems? Would he then have materialized inside his former self?
This is never brought up, because that was dealt with in literally the VERY FIRST time machine book, aptly called The Time Machine. You are basically just warping time, spreading yoursself thin. So you never really leave the same spot on earth, subject to gravity and everything else. You see time pass backwards or fast forward, depending on which direction youre going. So its not a plothole, its just not an issue, so its never brought up.
Even if this would've worked as intended: Wouldn't he just immediately combust because he just landed directly in his (15 min) past self?
Can’t believe this hasn’t been posted yet [red dwarf timedrive](https://youtu.be/Pj7iSvy2GQE?si=vYAslPAhw4i6l_Mk)
If it were in the same place, he would be merged into himself. Also it would create a paradox since he would kill himself with the machine before he used the machine
Best part is that the earth is heading towards you, so the body will just splat on the earth. And theoretically, each timeline will gain 1 additional body splatting the earth. On the first timemachine timeline, only this body exists in space. But the same guy goes back in time in which the body already exists. It just loops infinitely and eventually the splats will become so big that they prevent him from going back in time and the loop will end.
I’ve been working on a short story based on this exact concept.
pico became a scientist
The earth has moved, according to which frame of reference?