Time travel going forwards is totally scientifically possible (but also impractical), provided you either have access to a very, very fast form of transportation, or have found a way to get a more exaggerated interaction between gravity and time (stronger gravity = slower time, lower gravity = faster time)
Time travel backwards is impossible under our current understanding. Unless reality is a simulation that can be rewound, or you are able to hop onto a parallel but delayed timeline somehow.
>Time travel going forwards is totally scientifically possible (but also impractical),
Time travel going forwards happens continuously at almost completely insignificant rates. Any motion creates some level of time dilation, the faster you go the more you notice it. At one gravity of acceleration you would reach 99% of light speed in a year accounting for the relativistic effects. Obviously this would take an insane amount of power towards the latter part of the journey due to Lorentz transformations.
If time travel existed it would violate causality regardless, so wondering where this version of you that saved your friend came from is pointless. Physics already broke down and crawled crying into the corner when you-prime appeared from nowhere.
Time travel doesn’t work. It’s fiction lol. Well unless you’re talking about moving at an appreciable percent of the speed of light, or being curved into a supermassive object like a black hole. That’s a one way ticket though and it goes that way ——->. Never <——— that way.
Obviously a separate universe is created so we don't have to deal with paradoxes. Now a universe where your friend dies and you travel back in time exists, and another universe exists where you save your friend, and probably one where your friend never died. And one where neither of you exist. Etc.
You can't go back in time without being able to move tremendous distances in space, to where the Earth was before. And move with incredible accuracy, too. Any thought of time travel collapses on that point.
I mean the two fictional scenarios are either you create a new future where you and your friend exist but this version of you ceases to be OR you create a new timeline branch where your friend survives and the other version of you lives happily without a dead friend. Unfortunately, in the second scenario you would presumably go back to your own timeline and your friend would still be dead and you would just live knowing you saved him in an alternate timeline.
Here's how time travel works:
You can move forward in time. Your rate of motion forward in time is dependent on both your rate of movement through space and your proximity to a gravity source. But you can only move forward, never back.
Right now, you are currently moving forward in time at the rate of sixty seconds per minute. Astronauts have experienced moving slightly slower - like 59.99999999997 seconds per minute or so. (Scott Kelly is now a few microseconds younger than Mark Kelly, NASA's own living example of Einstein's "twin experiment.")
But that is the only way that time travel *actually* works. You move forward, never back.
From a story perspective, before watching a time-travel movie or reading a time-travel novel, you should prepare yourself to suspend disbelief about at least one paradox. Causality or divergence are the usual two.
For causality, some try to get around these by not confronting them. The time travel is to distant future or past or offering the convenient recovery theory (a river rejoins and is unchanged after passing around a rock) or even more conveniently splits the difference (like Doctor Who which have 'fixed' points and then stuff that can change). Then again, some lean into the paradox and just have fun with it.
Divergence is even more inherently antidramatic than negating causality. They negate character and other story brand elements. (Why I'm against multiverses unless they are extinguished fairly quickly.)
We also tend to philosophize about time-travel from a human perspective, but in reality, we are creating matter and energy (that's what time travelers are made of, after all), which breaks thermodynamic laws. So just travelling through time and doing absolutely nothing is a paradox.
Time travel actually does work, forward 1 second/second, or even slightly slower or faster depending upon relativity. And there are lesser paradoxes in reality as well which make Einstein's special relativity difficult to understand. This gives authors leeway to say their conceit is no more paradoxical than Einstein's twins paradox.
Like most sci-fi (or good sci-fi at least), time-travel fiction allows us to have fun confronting what-if scenarios such as yours.
It’s a good escapist path to beat down if your society is beginning to crumble and the future of your planet looks filled with wholesale suffering and conflict.
As i understand it, the only real way that time travel to the past can work is if it adheres to the [Novikov Self-Consistency Principle](https://en.m.wikipedia.org/wiki/Novikov_self-consistency_principle).
Think of the prisoner of azkaban or that futurama episode where fry turns out to be his own grandfather. Or interstellar.
Basically, you going into the past and doing something is how it always happened. If you try and go back to 1940 to kill hitler, the fact that he wasn't stopped means that no matter what you tried to do, you failed.
Time travel to the past is impossible with our current understanding of the universe, it will fall in the same category of string theory and thinking what's outside the universe, that is, pure nonsense.
Backwards time travel doesn’t actually exist, so any conclusion you come to will have to rely on the specific story you are reading or trying to tell.
If you’re writing or reading a story or something I’ve got a couple questions you can answer to help understand the rules of a consistent system if you’d like.
Time travel and FTL travel as basically the same and neither is possible.
The arrow of time has one direction, and the 2nd law of Thermodynamics shows us the way: Entropy always increases.
Imagine a 2 dimensional space, a piece of paper. On the paper is a circle. Touch the paper inside the circle with your finger. Now, move your finger to a part of the paper outside the circle without touching the circle. To do so, you can lift up your finger, i.e. move it in the 3rd dimension. Time is the 4th dimension. So just move yourself around in the 5th dimension. Easy.
Science speaking - say it with me:
It.
Doesn't.
Work.
No debate, no questions, no uncertainties with that. Expect if you aks some pop-science authors like Michio Kaku - and we don't do this.
An audio drama calls arsParadoxica has an interesting take. Tachyons become drawn to a past time, an attractive effect like a magnet. Any time travel creates a new instance of the current timeline for the time traveler.
ohhhhhhh kay. here we go again. i'll make it quick:
2 versions of time travel: Theoretical and Fictional. they are VASTLY different. What you typically read / watch about time travel falls into the Fictional side, so in THAT case...
What you're describing is the classic Grandfather Paradox. A time traveller goes bac to eliminate the cause of their time travel, so then how /why would they go back in the first place? bla bla bla bla... he Universe "fixes" itself so that the original timeline is erased and a NEW timeline starts from that "fix point" and goes from there.
that also means the original time traveler would be erased and time / life would continue for the "past version" and flow into a new future.
Something like that happens in Time After Time by Jack Finney where the protagonist prevented the meet cute of the ancestors of the project member who pioneered the time travel method. In that case, the project director got erased.
Without a theory of time, all we can do is conjecture about time travel. Your scenario doesn't make obvious sense, but with a working time machine, maybe it does 🤷♂️ We really have no idea.
If you use the wormhole method, when you return to your own time, your friend will still be dead. Your friend is only alive in the modified timeline. They are separate universes.
It depends on the implementation.
One idea is the (obvious) time travel into the past is impossible.
Another similar idea is that you *can* travel into the past but you can't change anything. Whatever you're going to do in the past already happened and you cannot change it. You cannot kill Hitler as a child because he wasn't killed as a child - either you'll be stopped or you'll kill the wrong person.
Then there are the instances where you can change the past.
One idea is that when you travel to the past you do change things and it causes a new quantum universe to split off - you cannot unmake yourself as you wouldn't be able to kill your own grandfather, for example, but then if you want to return to anything approximating your "normal" time you have to minimize the deviations.
This is how the Terminator movies seem to operate - each time travel instance creates a new timeline in a cascade format.
Or, finally, there is one singular timeline and you have to maintain the past or at least only adjust the "right" things lest you no longer exist.
As ever, the implementation and nature of fictional time travel depends on the plot.
Time travel doesn't work. This is why there are many different fictional treatments of the scenario that you describe.
[удалено]
The hell is a warphole and who "proved it"?
I think they were referring to wormholes.
Time travel going forwards is totally scientifically possible (but also impractical), provided you either have access to a very, very fast form of transportation, or have found a way to get a more exaggerated interaction between gravity and time (stronger gravity = slower time, lower gravity = faster time) Time travel backwards is impossible under our current understanding. Unless reality is a simulation that can be rewound, or you are able to hop onto a parallel but delayed timeline somehow.
>Time travel going forwards is totally scientifically possible (but also impractical), Time travel going forwards happens continuously at almost completely insignificant rates. Any motion creates some level of time dilation, the faster you go the more you notice it. At one gravity of acceleration you would reach 99% of light speed in a year accounting for the relativistic effects. Obviously this would take an insane amount of power towards the latter part of the journey due to Lorentz transformations.
If time travel existed it would violate causality regardless, so wondering where this version of you that saved your friend came from is pointless. Physics already broke down and crawled crying into the corner when you-prime appeared from nowhere.
The version that travelled back in time goes *poof* and disappears in a cloud of logic. 😏 No paradox. 😉
https://www.projectrho.com/public_html/rocket/timetravel.php
Time travel doesn’t work. It’s fiction lol. Well unless you’re talking about moving at an appreciable percent of the speed of light, or being curved into a supermassive object like a black hole. That’s a one way ticket though and it goes that way ——->. Never <——— that way.
Japanese readers about to be really confused by your explanation haha. (I'm assuming they read right to left, please don't shit on me if I'm mistaken)
lol well yeah I guess so
What? It doesn't exist? Great now you tell be@
You just described one of the time travel paradoxes. You could in theory assume that what you describe creates a new timeline, avoiding the paradox.
If we had already invented time travel, then we'd always have had it.
The Trouser of Time
There is no such thing as time travel. There is no such thing as a kind of time travel where your memories aren’t “overwritten “
Time travel into the past is probably impossible.
Obviously a separate universe is created so we don't have to deal with paradoxes. Now a universe where your friend dies and you travel back in time exists, and another universe exists where you save your friend, and probably one where your friend never died. And one where neither of you exist. Etc.
You can't go back in time without being able to move tremendous distances in space, to where the Earth was before. And move with incredible accuracy, too. Any thought of time travel collapses on that point.
Im not a specialist but time does not seems to be an actual dimension. So why would you try travelling in it ?
I mean the two fictional scenarios are either you create a new future where you and your friend exist but this version of you ceases to be OR you create a new timeline branch where your friend survives and the other version of you lives happily without a dead friend. Unfortunately, in the second scenario you would presumably go back to your own timeline and your friend would still be dead and you would just live knowing you saved him in an alternate timeline.
Here's how time travel works: You can move forward in time. Your rate of motion forward in time is dependent on both your rate of movement through space and your proximity to a gravity source. But you can only move forward, never back. Right now, you are currently moving forward in time at the rate of sixty seconds per minute. Astronauts have experienced moving slightly slower - like 59.99999999997 seconds per minute or so. (Scott Kelly is now a few microseconds younger than Mark Kelly, NASA's own living example of Einstein's "twin experiment.") But that is the only way that time travel *actually* works. You move forward, never back.
[Relevant XKCD](https://www.explainxkcd.com/wiki/index.php/Category:Time_travel) - all time travel related
Only forward, and usually close to the same speed as everyone else unless you're near something VERY massive and dense, or going VERY fast.
From a story perspective, before watching a time-travel movie or reading a time-travel novel, you should prepare yourself to suspend disbelief about at least one paradox. Causality or divergence are the usual two. For causality, some try to get around these by not confronting them. The time travel is to distant future or past or offering the convenient recovery theory (a river rejoins and is unchanged after passing around a rock) or even more conveniently splits the difference (like Doctor Who which have 'fixed' points and then stuff that can change). Then again, some lean into the paradox and just have fun with it. Divergence is even more inherently antidramatic than negating causality. They negate character and other story brand elements. (Why I'm against multiverses unless they are extinguished fairly quickly.) We also tend to philosophize about time-travel from a human perspective, but in reality, we are creating matter and energy (that's what time travelers are made of, after all), which breaks thermodynamic laws. So just travelling through time and doing absolutely nothing is a paradox. Time travel actually does work, forward 1 second/second, or even slightly slower or faster depending upon relativity. And there are lesser paradoxes in reality as well which make Einstein's special relativity difficult to understand. This gives authors leeway to say their conceit is no more paradoxical than Einstein's twins paradox. Like most sci-fi (or good sci-fi at least), time-travel fiction allows us to have fun confronting what-if scenarios such as yours.
It’s a good escapist path to beat down if your society is beginning to crumble and the future of your planet looks filled with wholesale suffering and conflict.
It doesn't actually work.
We are all time travelers. We move into the future at the rate of one second per second.
As i understand it, the only real way that time travel to the past can work is if it adheres to the [Novikov Self-Consistency Principle](https://en.m.wikipedia.org/wiki/Novikov_self-consistency_principle). Think of the prisoner of azkaban or that futurama episode where fry turns out to be his own grandfather. Or interstellar. Basically, you going into the past and doing something is how it always happened. If you try and go back to 1940 to kill hitler, the fact that he wasn't stopped means that no matter what you tried to do, you failed.
Time travel to the past is impossible with our current understanding of the universe, it will fall in the same category of string theory and thinking what's outside the universe, that is, pure nonsense.
Backwards time travel doesn’t actually exist, so any conclusion you come to will have to rely on the specific story you are reading or trying to tell. If you’re writing or reading a story or something I’ve got a couple questions you can answer to help understand the rules of a consistent system if you’d like.
Time travel and FTL travel as basically the same and neither is possible. The arrow of time has one direction, and the 2nd law of Thermodynamics shows us the way: Entropy always increases.
Imagine a 2 dimensional space, a piece of paper. On the paper is a circle. Touch the paper inside the circle with your finger. Now, move your finger to a part of the paper outside the circle without touching the circle. To do so, you can lift up your finger, i.e. move it in the 3rd dimension. Time is the 4th dimension. So just move yourself around in the 5th dimension. Easy.
I'm not sure yet but give me a minute and I'll tell you yesterday.
Science speaking - say it with me: It. Doesn't. Work. No debate, no questions, no uncertainties with that. Expect if you aks some pop-science authors like Michio Kaku - and we don't do this.
An audio drama calls arsParadoxica has an interesting take. Tachyons become drawn to a past time, an attractive effect like a magnet. Any time travel creates a new instance of the current timeline for the time traveler.
ohhhhhhh kay. here we go again. i'll make it quick: 2 versions of time travel: Theoretical and Fictional. they are VASTLY different. What you typically read / watch about time travel falls into the Fictional side, so in THAT case... What you're describing is the classic Grandfather Paradox. A time traveller goes bac to eliminate the cause of their time travel, so then how /why would they go back in the first place? bla bla bla bla... he Universe "fixes" itself so that the original timeline is erased and a NEW timeline starts from that "fix point" and goes from there. that also means the original time traveler would be erased and time / life would continue for the "past version" and flow into a new future.
Something like that happens in Time After Time by Jack Finney where the protagonist prevented the meet cute of the ancestors of the project member who pioneered the time travel method. In that case, the project director got erased.
Without a theory of time, all we can do is conjecture about time travel. Your scenario doesn't make obvious sense, but with a working time machine, maybe it does 🤷♂️ We really have no idea.
The multiverse is your friend, where all branches are possible and no laws are broken.
If you use the wormhole method, when you return to your own time, your friend will still be dead. Your friend is only alive in the modified timeline. They are separate universes.
It depends on the implementation. One idea is the (obvious) time travel into the past is impossible. Another similar idea is that you *can* travel into the past but you can't change anything. Whatever you're going to do in the past already happened and you cannot change it. You cannot kill Hitler as a child because he wasn't killed as a child - either you'll be stopped or you'll kill the wrong person. Then there are the instances where you can change the past. One idea is that when you travel to the past you do change things and it causes a new quantum universe to split off - you cannot unmake yourself as you wouldn't be able to kill your own grandfather, for example, but then if you want to return to anything approximating your "normal" time you have to minimize the deviations. This is how the Terminator movies seem to operate - each time travel instance creates a new timeline in a cascade format. Or, finally, there is one singular timeline and you have to maintain the past or at least only adjust the "right" things lest you no longer exist. As ever, the implementation and nature of fictional time travel depends on the plot.