As far as we know, the closest thing to time travel would have to be tachyons but so far, we haven't observed them.
But hey, you're already a time traveler. Look up in the sky; that moon you see, was the moon 1.3 seconds ago; the sun, is already 8 minutes older than you actually see. That new supernova everyone's going beserka about, actually happened about 2 millions years ago.
Yes we all travel in time every minute of everyday. Although only forward, and at a pace we cannot control!
Jokes aside, I do believe time travel is possible, by traveling faster than light.
The closer you are to the speed of light the slower time goes, until eventually stopping, and going backwards. Traveling faster than light however, is a rather large obstacle we need to overcome.
As for the second half of the question. The butterfly theory, if we change something in the past, everything will change in the future, and if you kill your own grandad, this would create a paradox...
This can be explained however, by multiple universes, parallel worlds where one decision goes one way, and another way on a different universe. Therefore, there are many universes like ours, one for each outcome of each and every decision.
I have to side with Stephen Hawkingon this. Time travel into the past is most likely impossible, but traveling into the future might be possible. Time slows down in areas where gravity is strong. So we could travel very quickly to a super massive black hole, where gravity is super strong and therefor time is super slow. If we went there and orbited for a day, hundreds of years will have past on Earth, buy the trip would have only been a day for the passengers. Therefor, you could reach the distant future in a short period of time, but you wouldnt be able to get back to your own time.
Yes. You are traveling forward in time right now and it fairly easy to change the rate at which you travel forward in time. Is traveling back in time possible. We it's not entirely outlawed by physics but I suspect it would take an infinite amount of energy so effectively it would be a problem.
Also don't forget the Earth is moving. If you went back say 10 minutes you would appear in deep space!
I get a chuckle out of some of these answers! It seems even the brightest people in the category don't realize we are traveling forward in time as we speak! Every breath you take, word you speak, action you make, you ARE traveling into the future! If you weren't you wouldn't have birthdays now would you?
I think No. There is one problem with time travel that you can not go in past and stop yourself from making(or buying or borrowing) the time machine due to which you came to the present time, from where you used the time machine and went into the past . This is a classic rookie time travel mistake.
The question of whether time travel is possible can be divided into three parts.
*pics given at end in links
Part One:
whether travel into the future is possible; second, whether travel into the past is possible; and third, whether some sort of curvature of time would make travel into the past possible, since it is also our future. The first, travel into the future, is possible, since special relativity allows for the twins paradox, in which time passes much more slowly for a person who travels close to the speed of light relative to a given inertial frame. The second, travel into the past, appears to be impossible, since it would require that a body be accelerated past the speed of light. The third would be the only way to travel into the past, but it would require alternative geometries of spacetime that may or not exist, and would imply paradoxes that perhaps cannot be overcome. I will deal with each of these in turn, referring primarily to special relativity, and what it teaches us about the equivalence of inertial frames.
Time travel into the future is in some sense possible. By accelerating to high speeds and then returning to Earth, it would make our time slow down significantly. This is not "true" time travel, as envisioned by Wells, in which the traveller simply disappears at one point in time and reappears at another point in time. In some sense, we are travelling to the future all the time - travelling to high speeds would simply enable us to survive the trip past our natural life spans. An immortal being with infinite patience would not have any interest in this process. It would, however, enable a traveler to travel, say, one thousand years in only a one-year "trip". As a traveller approaches the speed of light, he or she sees the original frame of time slow down according to a Lorentz transformation, t=1/(1-v2/c2)½. As one can see, as v approaches c, the denominator approaches zero, and the time elapsed approaches infinity. If one then returned to one's original inertial frame, much more time will have passed in the original frame than in one's own. The traveller could then travel back to Earth, again slowing time relative to the traveller's frame, and would return with only a small amount of time elapsed relative to the time passed on Earth. This is known as the "twins paradox", as two twins, one of whom boards such a time-travelling space ship, and another who waits at home, would be very different ages by the time the travelling twin returned. As such, time travel to the future of a sort is possible, in the sense that a person can hasten the Earth's time relative to himself or herself, and take a shorter trip through spacetime.
Time travel to the past is more complicated and most likely impossible. Though one may be able to "slow time down" relative to oneself (or speed it up, if one somehow managed to put Earth on a spaceship and send it away very, very fast), this is far from causing time to go backwards. No matter how much one slows down time, it is just slowed down. However, looking at the original transformation, t=1/(1-v2/c2)½, one can see that if v were higher than c, the denominator would become imaginary. This would enable the traveller to travel back through time. It seems that if one had an even faster spaceship, one could leave earth and then return at an even earlier time. Unfortunately, acceleration past the speed of light is not possible, as the Lorentz transformation applies to mass as well as space and time. Let m be the mass of an object relative to a measuring frame, and let m0 be its mass relative to its own frame. In this case, m= m0/(1-v2/c2)½. Just as with time, relative mass would increase toward infinity as the object approaches the speed of light, as the denominator would approach zero. It would take an infinite amount of force, then, to accelerate an object to or past the speed of light relative to a given frame, and it is impossible to generate an infinite amount of force. Therefore, no object can travel faster than the speed of light, and travel backwards in time would be impossible through the "acceleration method" we used to travel forward in time. While an object may take an infinite amount of force to accelerate to the speed of light, analogously, an object that was already travelling faster than the speed of light would take an infinite amount of force to decelerate to c. Hence, one would need to take into account one's "starting speed". These theoretical "faster than light" particles have been called "tachyons" (from the Greek word tachys, meaning "fast"). However, no one has ever seen evidence of these tachyons, though whether this is because they do not exist or because their backwards travel makes them impossible to interact with is uncertain. Were they even to exist, it would not solve the problem that we are not ourselves travelling faster than the speed of light, and could never accelerate to such a point.
Answers & Comments
Verified answer
As far as we know, the closest thing to time travel would have to be tachyons but so far, we haven't observed them.
But hey, you're already a time traveler. Look up in the sky; that moon you see, was the moon 1.3 seconds ago; the sun, is already 8 minutes older than you actually see. That new supernova everyone's going beserka about, actually happened about 2 millions years ago.
Welcome to the future. ^.^
Yes we all travel in time every minute of everyday. Although only forward, and at a pace we cannot control!
Jokes aside, I do believe time travel is possible, by traveling faster than light.
The closer you are to the speed of light the slower time goes, until eventually stopping, and going backwards. Traveling faster than light however, is a rather large obstacle we need to overcome.
As for the second half of the question. The butterfly theory, if we change something in the past, everything will change in the future, and if you kill your own grandad, this would create a paradox...
This can be explained however, by multiple universes, parallel worlds where one decision goes one way, and another way on a different universe. Therefore, there are many universes like ours, one for each outcome of each and every decision.
I have to side with Stephen Hawkingon this. Time travel into the past is most likely impossible, but traveling into the future might be possible. Time slows down in areas where gravity is strong. So we could travel very quickly to a super massive black hole, where gravity is super strong and therefor time is super slow. If we went there and orbited for a day, hundreds of years will have past on Earth, buy the trip would have only been a day for the passengers. Therefor, you could reach the distant future in a short period of time, but you wouldnt be able to get back to your own time.
Yes. You are traveling forward in time right now and it fairly easy to change the rate at which you travel forward in time. Is traveling back in time possible. We it's not entirely outlawed by physics but I suspect it would take an infinite amount of energy so effectively it would be a problem.
Also don't forget the Earth is moving. If you went back say 10 minutes you would appear in deep space!
I get a chuckle out of some of these answers! It seems even the brightest people in the category don't realize we are traveling forward in time as we speak! Every breath you take, word you speak, action you make, you ARE traveling into the future! If you weren't you wouldn't have birthdays now would you?
I think No. There is one problem with time travel that you can not go in past and stop yourself from making(or buying or borrowing) the time machine due to which you came to the present time, from where you used the time machine and went into the past . This is a classic rookie time travel mistake.
If so, then the Titanic actually sank because there were hundreds of thousands of time travelers appearing on the ship all at once.
Your hand touching everything is a time. So, my answer is no.
The question of whether time travel is possible can be divided into three parts.
*pics given at end in links
Part One:
whether travel into the future is possible; second, whether travel into the past is possible; and third, whether some sort of curvature of time would make travel into the past possible, since it is also our future. The first, travel into the future, is possible, since special relativity allows for the twins paradox, in which time passes much more slowly for a person who travels close to the speed of light relative to a given inertial frame. The second, travel into the past, appears to be impossible, since it would require that a body be accelerated past the speed of light. The third would be the only way to travel into the past, but it would require alternative geometries of spacetime that may or not exist, and would imply paradoxes that perhaps cannot be overcome. I will deal with each of these in turn, referring primarily to special relativity, and what it teaches us about the equivalence of inertial frames.
Time travel into the future is in some sense possible. By accelerating to high speeds and then returning to Earth, it would make our time slow down significantly. This is not "true" time travel, as envisioned by Wells, in which the traveller simply disappears at one point in time and reappears at another point in time. In some sense, we are travelling to the future all the time - travelling to high speeds would simply enable us to survive the trip past our natural life spans. An immortal being with infinite patience would not have any interest in this process. It would, however, enable a traveler to travel, say, one thousand years in only a one-year "trip". As a traveller approaches the speed of light, he or she sees the original frame of time slow down according to a Lorentz transformation, t=1/(1-v2/c2)½. As one can see, as v approaches c, the denominator approaches zero, and the time elapsed approaches infinity. If one then returned to one's original inertial frame, much more time will have passed in the original frame than in one's own. The traveller could then travel back to Earth, again slowing time relative to the traveller's frame, and would return with only a small amount of time elapsed relative to the time passed on Earth. This is known as the "twins paradox", as two twins, one of whom boards such a time-travelling space ship, and another who waits at home, would be very different ages by the time the travelling twin returned. As such, time travel to the future of a sort is possible, in the sense that a person can hasten the Earth's time relative to himself or herself, and take a shorter trip through spacetime.
Time travel to the past is more complicated and most likely impossible. Though one may be able to "slow time down" relative to oneself (or speed it up, if one somehow managed to put Earth on a spaceship and send it away very, very fast), this is far from causing time to go backwards. No matter how much one slows down time, it is just slowed down. However, looking at the original transformation, t=1/(1-v2/c2)½, one can see that if v were higher than c, the denominator would become imaginary. This would enable the traveller to travel back through time. It seems that if one had an even faster spaceship, one could leave earth and then return at an even earlier time. Unfortunately, acceleration past the speed of light is not possible, as the Lorentz transformation applies to mass as well as space and time. Let m be the mass of an object relative to a measuring frame, and let m0 be its mass relative to its own frame. In this case, m= m0/(1-v2/c2)½. Just as with time, relative mass would increase toward infinity as the object approaches the speed of light, as the denominator would approach zero. It would take an infinite amount of force, then, to accelerate an object to or past the speed of light relative to a given frame, and it is impossible to generate an infinite amount of force. Therefore, no object can travel faster than the speed of light, and travel backwards in time would be impossible through the "acceleration method" we used to travel forward in time. While an object may take an infinite amount of force to accelerate to the speed of light, analogously, an object that was already travelling faster than the speed of light would take an infinite amount of force to decelerate to c. Hence, one would need to take into account one's "starting speed". These theoretical "faster than light" particles have been called "tachyons" (from the Greek word tachys, meaning "fast"). However, no one has ever seen evidence of these tachyons, though whether this is because they do not exist or because their backwards travel makes them impossible to interact with is uncertain. Were they even to exist, it would not solve the problem that we are not ourselves travelling faster than the speed of light, and could never accelerate to such a point.
To be continues to Part Two
No and no.