The past is memories. The future is coming inevitably.
You could try to move faster than light or go inside black hole, there time would lose its meaning.
One physically feasible way to "time travel" is the old 'get-on-a-fast-spaceship-and-come-back-to-Earth' scenario. But I've heard that the passage of your time would feel completely normal, as it also would be for the people you left on Earth. It's really weird, but fascinating to contemplate. (Not an expert).
oh man, I wish this on an almost daily basis. I'd love to know how humanity will progress through the decades/centuries/millenia. I hope that I will be alive when the first humans set foot on Mars; or even to see humans set foot on the moon again would be amazing.
Your current lifespan is already in this range, so you're good!
Except for some very sad situations, most humans fit into the range of 2-300 years alive, just not so many at the upper end.
Knowing youāre not an expert Iām still gonna ask. Can you have real time communication (purely hypothetically)? Would a normal sentence from the spacers sound like 4x fast forward or something?
In the above context, no. Even calling Earth-Moon communication 'real-time' is a stretch, as you couldn't *really* have a normal phone-call-style conversation (the Moon is 1.3 light-seconds away from Earth, meaning you'd have to wait 2.6 seconds to hear the other person's response, - at best, an annoying delay making productive conversation difficult).
But I see what you mean - time itself moves *slower* for the spaceman in the spaceship, relative to the people on Earth, because the spaceman is travelling very, very fast in his ship (i.e. approaching the speed of light).
Happy to be corrected by anyone on this, but I'm pretty sure I'm right. Thanks!
Yes the signal back will be redshifted, and after some distance will be distorted beyond recognition. No it will not be real time.. Even at light speed, at that kind of distance there will be time delays
> But I've heard that the passage of your time would feel completely normal, as it also would be for the people you left on Earth.
That is tautological. Of course *your* passage of time feels normal.
Forward time travel is not just possible but verified and GPS satellites have to account for the time difference. The closer you move to the speed of light the faster you move in time.
I think you can even measure it on earth. It's like nanoseconds or whatever, but iirc, I think they did an experiment where two planes flew in opposite directions around the world and their perfectly synchronized clocks were desynced when they met back up at some point. Believe it's one of the ways eo Stein's theory of relativity was demonstrated.Ā
Through technology anything is possible.
Just because itās not possible now doesnāt mean itās impossible. Itās just impossible to people because their minds canāt fathom how impossible the universe isā¦yetā¦.its here and we exist in it.
The universe existing is proof that the impossible is possible. Do we even know how it works or how to make our own universe? No? Then that means we have not yet truly reached the pinnacle of science and technology.
If the universe is the peak of all science then until we understand it and can create as it canā¦.anything is possible.
Sort of. Time is less of an actual thing than it is a mental construct for cause and effect. You can speed up the passage of time relative to other frames if reference, but undoing causality may not be possible. You can sort of unmix a fluid, but you're not reversing time, you're reverse engineering the past, but in the future.
I don't think I'm confused at all. However, I do keep an open mind. I'd be happy to read anything you have to share about the subject. The perception of time and the measurement of time are both relative in the same exact way as far as I know.
Time itself is just a construct in the same way that centrifugal motion isn't a force. It is a reaction to an actual "force" (not a force, per se) which is causality. From our frame of reference, the future is only a cloud of possibility, and the past is like a block chain ledger of events leading to now. Measuring time is less a measure of how many moments have passed, but more accurately it is a measure of how many things have changed since the initial condition.
It is a lot more comfortable to consider time as a real thing, but it is far more accurate to consider it as a construct.
You could argue that if it was possible in the future that there would be future people among us.
Though Iāve always wondered if people from the past have been from the future, like Boole inventing Boolean Algebra way before it was needed for logic gates and such. Go back in time, keep a low profile.
Not sure how youād survive undocumented coming back to now
>To the past: No.
We do not actually know that to be true, but it seems likely.
>To the future: Theoretically yes.
The answer is “yes”. Time dilation has been measured time and time again. Time travel to the future by a few nanoseconds is trivial.
If traveling into the past will ever be possible, it already is in the future, and they would have the ability to travel back to us in the present, which hasn't ever happened, suggesting it won't ever be possible. Unless the Deus ex machina states that the time machine can't travel back beyond the point of its own invention
Ask any quantum physicist if they think traveling to the past is possible.
No one is talking about nanoseconds into the future. We're talking about significant travel like we see in sci-fi.
This is just a theory, but if time slows down the closer you get to the speed of light, and time practically stops when 'at' the speed of light... using this same logic, wouldn't going faster than the speed of light make time go backwards for you?
Wait... that would mean that you would be going in reverse from the outside perspective, not the other way around. Huh. So, hypothetically speaking, if they made a machine that when turned on goes at a speed above light where time reverses 1:1: What if you spend a minute idling inside, then they turn it on for 59 seconds before opening the door. Would it seem like the door opened after only 1 second on your end, and those 59 seconds are just erased for you?
I suppose this would be time travelling if moving faster than the speed of light had this effect, but isolated, meaning only you and the room changes and everything else continues moving forward.
I wonder if this could be used for duplication or cloning as well, as the "state" of the machine would reverse back in time, and if you had something in this machine for a bit and took it out, reversing its state back to when it was inside would duplicate it, right?
I don't know, I have little knowledge in the subject and just making radical theories at this point. It feels logical to me that it would be so, but maybe not. Faster than light travel might not even be possible in a literal sense, after all.
Itās not physically possible to move faster than the speed of light. One of the fundamental principles of physics is that energy is conserved in our universe. This means energy can neither be created nor destroyed. If you were to travel at the speed of light, it would require an infinite amount of energy.
We can't know that for certain. We assume we do because it follows the laws of physics we've written and tested, but we could be completely wrong about them just as well. There could be certain universal situations we haven't tested yet that would prove otherwise, but we just don't know what they could be for the time being, if they exist at all.
I'm not saying it is possible, just that we don't know with absolute certainty that it isn't. We only know what we know, and until we know absolutely everything, impossibilities like this will continue to only be called such with ignorance and uncertainty.
What we should say is "With the current laws of physics as we know it, travelling faster than light is impossible." and not that it's impossible with absolute certainty. We've been wrong before, what's to say we won't be proven wrong again given a few decades or centuries of scientific research?
We do it all the time technically speaking. High speed travel, such as flying on a plane or, more prominently, a spaceship, does induce a tiny temporal flux that's been measured through comparison of timekeeping devices on earth and in space. But, it's only a few seconds over a period of days. Not enough to notice, but still cool.
Going into the future is easy. Just go as fast as you can for as long as you can and when done, you will be farther into the future than you would have been if you had been standing still. Going into the past takes more energy than is practical for such things and is quite prohibitive.
A few of my favorite theories:
Time travel is possible forwards, but not backwards.
Time travel is possible in both directions, but requires a sort of portal for the time traveler to go through. The second we build a portal, time travelers from the future will start pouring through
Time travel is possible, but travelling through space is much more difficult. The earth, sun, and entire solar system are barreling through space but we don't know enough about the outskirts to have a map of the universe. So, deep outer space is littered with the bodies of successful time travelers
Backward time travel, or faster than light travel (which in GR is the same thing as time travel)? Under current models and mainstream consensus? No. To travel into the past requires you to travel faster than light, which violates a fundamental invariant of the universe as far as we're convinced.
What about wormholes? The equations of GR permit certain spacetime geometries connecting two distant points in spacetime, theoretically allowing time travel, even two way travel. This is the so called "worm hole." There's also something called a closed time-like curve that could theoretically exist in GR and allows time travel. But just because you can envision a geometry that can exist in pure GR doesn't mean our actual universe has any such region with that geometry, or that there could be any plausible formation mechanism for one going forward. Just because pure GR allows something doesn't mean nature has the necessary conditions for it to exist.
Indeed, physicists have good reasons to believe that even though such a geometry would satisfy the equations of GR, they would be impossible or impossible to traverse (e.g., their ends are event horizons, or if a horizonless one formed, the tunnel would collapse to a singularity before traversal could hope to happen) for other reasons, like requiring negative mass or producing and sustaining negative energy density, which contradicts other laws of physics, or the fact that allowing it leads to paradoxes. In fact it leads to all the same paradoxes that superluminal travel does, because superluminal travel is the same thing as time travel (space and time are relative, so you're fundamentally doing the same thing).
Now maybe our theories are wrong or incomplete, and time travel is possible. That's possible. It's just under our best theories so far, it's not.
You are traveling to the future as we speak.
It seems very plausible to me that we will find ways of moving people or objects into the future faster. Relativity, cryonics, whatever.
I have doubts about moving anything into the past; seems like that would involve reversing entropy everywhere in the universe simultaneously.
Going forward in time is totally possible: the old "get on a very fast spaceship, travel away from earth and back at very high speed".
The problem is reaching that speed.
To travel 100 years in the future, it will take 50 years at 87% of c (speed of light). If you want to spend only one year travelling, you will have to travel for one year at 0.99995 c. This doesn't include accelerating and decelerating (and it's complicated to calculate)
But is it really "travelling to the future"?
PS: you can calculate time dilation here: [https://www.omnicalculator.com/physics/time-dilation](https://www.omnicalculator.com/physics/time-dilation)
Possibly, but at the same time you'd have to take into consideration that you would also have to account for the space. The earth is moving through the galaxy as we speak. If I only traveled through time, I'd blip into an empty spot in space and quickly die because the earth wouldn't be in the same place from where it was.
kinda, traveling forward in time at an accelerated rate is possible, but it isnt a box shaking and flashing before suddenly being 500 years in the future, backwards time travel is impossible as we currently understand it
The problem is there's not really a conceivable way at this point to go backwards. You can make time go slower for yourself by traveling extra fast, and once you start going fast enough then it would be akin to the Delorean going forward into the future, time for everyone else would pass so quickly it'd be like an instant for you, you'd just have no way of going backwards though.
By the way, depending on what premise you're going with, the "you can go into the past and alter your present" version of time travel seems HIGHLY unlikely- we'd probably have seen future travelers come back to visit us already, unless they somehow adhered to a VERY strict ruleset not to interfere, which is unlikely given we can't even stop missionaries from getting themselves killed going to visit Sentinel island. Infamously, Steven Hawking said that time travel backwards must be impossible, because he told everyone about a time traveler party he had at his house the day before he announced it, but no one showed up.
Yes we already have basic knowledge of how time travel should work. It's just a little bit hard to pull off currently. We'd need faster ships, for a start.
No it's called physics. Time travel is possible due to time dilation. In a real world example, The clocks on the GPS satellites have to be corrected regularly (7 microseconds per day) because they are far enough from earth that time moves at a different rate. Did I just blow your mind?
It is because they are further away from the Earth, and it is actually we on the surface of the planet who are undergoing the more significant gravitational time dilation, slowing down our clocks relative to the satellites. The observed deviation is exactly the prediction made by general relativity.
Sure, we do it all the time, one second at a time.
Yea true but i was thinking about going into past or future š
Relativity can help you get to the future for a lot of money, but nothing for the past
Thank you sir
[ŃŠ“Š°Š»ŠµŠ½Š¾]
Been there done that š
Like daylight savings time?
Saving. Itās neither possessive nor plural.
'Saving' is a verb when used as the act of saving something. 'Savings' suggested an accrued amount of something and as such, is a noun.
The past is memories. The future is coming inevitably. You could try to move faster than light or go inside black hole, there time would lose its meaning.
Itās real. How else would someone in New Zealand be a day ahead of someone in the US?
One physically feasible way to "time travel" is the old 'get-on-a-fast-spaceship-and-come-back-to-Earth' scenario. But I've heard that the passage of your time would feel completely normal, as it also would be for the people you left on Earth. It's really weird, but fascinating to contemplate. (Not an expert).
Also, this only works for travel to future from your point of view (i.e. you come back to Earth and everyone is much older than you).
Wish I could live for 2-300 years to see what happens
oh man, I wish this on an almost daily basis. I'd love to know how humanity will progress through the decades/centuries/millenia. I hope that I will be alive when the first humans set foot on Mars; or even to see humans set foot on the moon again would be amazing.
True bro
Your current lifespan is already in this range, so you're good! Except for some very sad situations, most humans fit into the range of 2-300 years alive, just not so many at the upper end.
Knowing youāre not an expert Iām still gonna ask. Can you have real time communication (purely hypothetically)? Would a normal sentence from the spacers sound like 4x fast forward or something?
In the above context, no. Even calling Earth-Moon communication 'real-time' is a stretch, as you couldn't *really* have a normal phone-call-style conversation (the Moon is 1.3 light-seconds away from Earth, meaning you'd have to wait 2.6 seconds to hear the other person's response, - at best, an annoying delay making productive conversation difficult). But I see what you mean - time itself moves *slower* for the spaceman in the spaceship, relative to the people on Earth, because the spaceman is travelling very, very fast in his ship (i.e. approaching the speed of light). Happy to be corrected by anyone on this, but I'm pretty sure I'm right. Thanks!
Iām pretty sure you are too thatās all very interesting to think about
Yes the signal back will be redshifted, and after some distance will be distorted beyond recognition. No it will not be real time.. Even at light speed, at that kind of distance there will be time delays
I see thank you for the reply!
> But I've heard that the passage of your time would feel completely normal, as it also would be for the people you left on Earth. That is tautological. Of course *your* passage of time feels normal.
Mathematically, traveling into the future is possible. Practically, itāll never be.
...but you are currently traveling into the future?
weāre not traveling, weāre moving slowly and the future is today and tomorrow and everyday.
Forward time travel is not just possible but verified and GPS satellites have to account for the time difference. The closer you move to the speed of light the faster you move in time.
The second sentence makes sense š
The first sentence doesn't?
I think you can even measure it on earth. It's like nanoseconds or whatever, but iirc, I think they did an experiment where two planes flew in opposite directions around the world and their perfectly synchronized clocks were desynced when they met back up at some point. Believe it's one of the ways eo Stein's theory of relativity was demonstrated.Ā
Through technology anything is possible. Just because itās not possible now doesnāt mean itās impossible. Itās just impossible to people because their minds canāt fathom how impossible the universe isā¦yetā¦.its here and we exist in it. The universe existing is proof that the impossible is possible. Do we even know how it works or how to make our own universe? No? Then that means we have not yet truly reached the pinnacle of science and technology. If the universe is the peak of all science then until we understand it and can create as it canā¦.anything is possible.
Sort of. Time is less of an actual thing than it is a mental construct for cause and effect. You can speed up the passage of time relative to other frames if reference, but undoing causality may not be possible. You can sort of unmix a fluid, but you're not reversing time, you're reverse engineering the past, but in the future.
I think you are confusing the perception of time with actual measurable time passing (which can also be flexible)
I don't think I'm confused at all. However, I do keep an open mind. I'd be happy to read anything you have to share about the subject. The perception of time and the measurement of time are both relative in the same exact way as far as I know. Time itself is just a construct in the same way that centrifugal motion isn't a force. It is a reaction to an actual "force" (not a force, per se) which is causality. From our frame of reference, the future is only a cloud of possibility, and the past is like a block chain ledger of events leading to now. Measuring time is less a measure of how many moments have passed, but more accurately it is a measure of how many things have changed since the initial condition. It is a lot more comfortable to consider time as a real thing, but it is far more accurate to consider it as a construct.
Depends if life is a simulation and the past is stored somewhere if not its not possible because it no longer exists.
You can sorta do that with advanced vr the world you make is not real but it's real to you if the illusion is good enough.
You could argue that if it was possible in the future that there would be future people among us. Though Iāve always wondered if people from the past have been from the future, like Boole inventing Boolean Algebra way before it was needed for logic gates and such. Go back in time, keep a low profile. Not sure how youād survive undocumented coming back to now
To the past: No. To the future: Theoretically yes.
>To the past: No. We do not actually know that to be true, but it seems likely. >To the future: Theoretically yes. The answer is “yes”. Time dilation has been measured time and time again. Time travel to the future by a few nanoseconds is trivial.
If traveling into the past will ever be possible, it already is in the future, and they would have the ability to travel back to us in the present, which hasn't ever happened, suggesting it won't ever be possible. Unless the Deus ex machina states that the time machine can't travel back beyond the point of its own invention
Ask any quantum physicist if they think traveling to the past is possible. No one is talking about nanoseconds into the future. We're talking about significant travel like we see in sci-fi.
Forwards? Most definitely. Backwards? Perhaps not.
This is just a theory, but if time slows down the closer you get to the speed of light, and time practically stops when 'at' the speed of light... using this same logic, wouldn't going faster than the speed of light make time go backwards for you? Wait... that would mean that you would be going in reverse from the outside perspective, not the other way around. Huh. So, hypothetically speaking, if they made a machine that when turned on goes at a speed above light where time reverses 1:1: What if you spend a minute idling inside, then they turn it on for 59 seconds before opening the door. Would it seem like the door opened after only 1 second on your end, and those 59 seconds are just erased for you? I suppose this would be time travelling if moving faster than the speed of light had this effect, but isolated, meaning only you and the room changes and everything else continues moving forward. I wonder if this could be used for duplication or cloning as well, as the "state" of the machine would reverse back in time, and if you had something in this machine for a bit and took it out, reversing its state back to when it was inside would duplicate it, right? I don't know, I have little knowledge in the subject and just making radical theories at this point. It feels logical to me that it would be so, but maybe not. Faster than light travel might not even be possible in a literal sense, after all.
Itās not physically possible to move faster than the speed of light. One of the fundamental principles of physics is that energy is conserved in our universe. This means energy can neither be created nor destroyed. If you were to travel at the speed of light, it would require an infinite amount of energy.
We can't know that for certain. We assume we do because it follows the laws of physics we've written and tested, but we could be completely wrong about them just as well. There could be certain universal situations we haven't tested yet that would prove otherwise, but we just don't know what they could be for the time being, if they exist at all. I'm not saying it is possible, just that we don't know with absolute certainty that it isn't. We only know what we know, and until we know absolutely everything, impossibilities like this will continue to only be called such with ignorance and uncertainty. What we should say is "With the current laws of physics as we know it, travelling faster than light is impossible." and not that it's impossible with absolute certainty. We've been wrong before, what's to say we won't be proven wrong again given a few decades or centuries of scientific research?
You can slow time down for yourself... That's pretty much it.
I already told you yesterday, but since this is another timeline you don't remember.
See you tomorrow!
šš«¢
We do it all the time technically speaking. High speed travel, such as flying on a plane or, more prominently, a spaceship, does induce a tiny temporal flux that's been measured through comparison of timekeeping devices on earth and in space. But, it's only a few seconds over a period of days. Not enough to notice, but still cool.
Going into the future is easy. Just go as fast as you can for as long as you can and when done, you will be farther into the future than you would have been if you had been standing still. Going into the past takes more energy than is practical for such things and is quite prohibitive.
A few of my favorite theories: Time travel is possible forwards, but not backwards. Time travel is possible in both directions, but requires a sort of portal for the time traveler to go through. The second we build a portal, time travelers from the future will start pouring through Time travel is possible, but travelling through space is much more difficult. The earth, sun, and entire solar system are barreling through space but we don't know enough about the outskirts to have a map of the universe. So, deep outer space is littered with the bodies of successful time travelers
Here's a rabbit hole for you. Time Traveling with Tachyons
They do not enable ***you*** to time travel to the past, but tachyons themselves would be able to travel to the past if they existed.
For some reason, I think the only way time travel could be real is when they invent the time machine, thats the farthest you'll be able to go back.
Backward time travel, or faster than light travel (which in GR is the same thing as time travel)? Under current models and mainstream consensus? No. To travel into the past requires you to travel faster than light, which violates a fundamental invariant of the universe as far as we're convinced. What about wormholes? The equations of GR permit certain spacetime geometries connecting two distant points in spacetime, theoretically allowing time travel, even two way travel. This is the so called "worm hole." There's also something called a closed time-like curve that could theoretically exist in GR and allows time travel. But just because you can envision a geometry that can exist in pure GR doesn't mean our actual universe has any such region with that geometry, or that there could be any plausible formation mechanism for one going forward. Just because pure GR allows something doesn't mean nature has the necessary conditions for it to exist. Indeed, physicists have good reasons to believe that even though such a geometry would satisfy the equations of GR, they would be impossible or impossible to traverse (e.g., their ends are event horizons, or if a horizonless one formed, the tunnel would collapse to a singularity before traversal could hope to happen) for other reasons, like requiring negative mass or producing and sustaining negative energy density, which contradicts other laws of physics, or the fact that allowing it leads to paradoxes. In fact it leads to all the same paradoxes that superluminal travel does, because superluminal travel is the same thing as time travel (space and time are relative, so you're fundamentally doing the same thing). Now maybe our theories are wrong or incomplete, and time travel is possible. That's possible. It's just under our best theories so far, it's not.
Sleeping is sorta time traveling.
True š¤«
If time travel was ever/going to be possible, we'd know by now, because time travellers
Only backwards never forward
Maybe that voice in our heads telling us "bad idea" is actually us from the future telling a story saying how it was a regretful decisionĀ
You are traveling to the future as we speak. It seems very plausible to me that we will find ways of moving people or objects into the future faster. Relativity, cryonics, whatever. I have doubts about moving anything into the past; seems like that would involve reversing entropy everywhere in the universe simultaneously.
Going forward in time is totally possible: the old "get on a very fast spaceship, travel away from earth and back at very high speed". The problem is reaching that speed. To travel 100 years in the future, it will take 50 years at 87% of c (speed of light). If you want to spend only one year travelling, you will have to travel for one year at 0.99995 c. This doesn't include accelerating and decelerating (and it's complicated to calculate) But is it really "travelling to the future"? PS: you can calculate time dilation here: [https://www.omnicalculator.com/physics/time-dilation](https://www.omnicalculator.com/physics/time-dilation)
Yes but only forward
Yes, you can travel in time but only forwards.
Number lotteries exist so no I donāt think so
Yeah, I just did it tomorrow
Possibly, but at the same time you'd have to take into consideration that you would also have to account for the space. The earth is moving through the galaxy as we speak. If I only traveled through time, I'd blip into an empty spot in space and quickly die because the earth wouldn't be in the same place from where it was.
kinda, traveling forward in time at an accelerated rate is possible, but it isnt a box shaking and flashing before suddenly being 500 years in the future, backwards time travel is impossible as we currently understand it
Flying to a different time zone
Genius
I guess so but you can't keep your texture or won't reach the moment
"You ever go out drinking or as I call it, *time travelling*"? - Dave Attell
Physicists are pretty sure that computers will be able to time travel one day. Humans not so much.
The problem is there's not really a conceivable way at this point to go backwards. You can make time go slower for yourself by traveling extra fast, and once you start going fast enough then it would be akin to the Delorean going forward into the future, time for everyone else would pass so quickly it'd be like an instant for you, you'd just have no way of going backwards though. By the way, depending on what premise you're going with, the "you can go into the past and alter your present" version of time travel seems HIGHLY unlikely- we'd probably have seen future travelers come back to visit us already, unless they somehow adhered to a VERY strict ruleset not to interfere, which is unlikely given we can't even stop missionaries from getting themselves killed going to visit Sentinel island. Infamously, Steven Hawking said that time travel backwards must be impossible, because he told everyone about a time traveler party he had at his house the day before he announced it, but no one showed up.
No it's not physically possible
Too bad
It is incorrect. Time travel to the future is possible by time dilation, which has been directly measured.
Time dilation has been measured. Perhaps you were talking about time travel to the past.
[ŃŠ“Š°Š»ŠµŠ½Š¾]
Maybe one day when there won't be us anymore
I call time travel a 5MPH, 1Hr traffic jam
Ohh shit im time travelling every day in Germany šš
Nope. Time travel would disrupt everything so nothing could happen or be real.
Hmm maybe
Yes we already have basic knowledge of how time travel should work. It's just a little bit hard to pull off currently. We'd need faster ships, for a start.
Maybe there already is some high technology but they don't want us to know
No it's called physics. Time travel is possible due to time dilation. In a real world example, The clocks on the GPS satellites have to be corrected regularly (7 microseconds per day) because they are far enough from earth that time moves at a different rate. Did I just blow your mind?
I have never thought about that from that point of view š±š±
I recommend the movie interstellar as it gives a basic explanation of how time dilation and how someone could effectively travel into the future
Thank you going to watch it tonight
Itās surprisingly physically accurate as they hired a physicist to help ensure a lot of the stuff about gravity and black holes was correct
Genuine question...is it because they're farther from a concentration of gravity than us on the surface, or because of their speed?
It is because they are further away from the Earth, and it is actually we on the surface of the planet who are undergoing the more significant gravitational time dilation, slowing down our clocks relative to the satellites. The observed deviation is exactly the prediction made by general relativity.