If time travel is possible (regardless of whether or not we can do it yet), does that mean that time travellers from the future may have already altered our present- and we do not know about it, seeing as we would be unaware?
Also is it possible that time travel will happen in the future, and that time travellers will travel back to a period which is still our future (for example they travel back from the year 2500 to 2400)?
I know I haven't got much of a grasp of the concept, but thanks!
2007-03-13 06:25:27 · 16 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Your question is a contradiction....
2007-03-13 06:28:21 · answer #1 · answered by ~♥~mama-to-be~♥~ 4 · 0⤊ 1⤋
The only situation under which time travel is possible is in travelling into the future, and this merely functions because of time travelling at relative speeds (if you go off on a space ship at near to the speed of light, then come back to earth, then time on earth will travel much faster than time in your space ship, so you will essentially have moved into the future without ageing much). However, travel into the past is impossible, because it involves travelling faster than the speed of light. It is also logically not possible - there is the grandfather paradox that has already been mentioned. It doesn't matter if you determine not to kill your grandfather, the fact that it's possible instantly nullifies the possibility of backwards time travel.
Time travel is a great concept as far as science fiction goes, giving sci-fi writers great material, but it just isn't possible! Time that has passed has already passed, and can't be revisited.
2007-03-13 15:25:59 · answer #2 · answered by canislupus 3 · 0⤊ 0⤋
If time travel is possible; You can't travel back in time and change things - because you've already travelled back in time and changed it. The present you see now would include the changes that your future self has already made in the past.
The reasoning behind this is that time couldn't be linear, moving from second to second - but everything that ever has occurred or will occur (from out viewpoint) has already happened.
This is a horrid thought as it would suggest that my life, and everyone else's is predetermined and it doesn't matter what I do, it because I'm just following the script.
But it's not possible so there's no need to worry about it.
2007-03-13 11:13:21 · answer #3 · answered by mark 7 · 0⤊ 0⤋
As time progresses in a uniform forward direction. Too out perception anyway. Suggests that the future cannot have already happened. Therefore. It would be impossible for us to meet a time traveller from the future. And as we already know that time travel has as yet not been mastered. Then we can safely assume. That time travel has not been achieved up to now. But may one day occur in the future. Then again I flip burgers for a living so what do I know
2007-03-15 12:03:49 · answer #4 · answered by Anonymous · 0⤊ 0⤋
The question about time travel fascinates me, as well. Who knows if it will ever be possible, so anything is possible when considering it. So, yes both scenarios you presented are possible. It is even possible that time travel has already been invented, and used. I mean what is to say that time travel is plausible, and one result of time travel was total annihilation of the world? So, in order to prevent the destruction from happening, some one, or some people travelled back in time, before time travel was invented, and prevented the machine, and it's technology from ever existing? Are you with me? Like I said, anything is possible, when you are thinking of stuff that hasn't yet happened.........
2007-03-13 06:33:34 · answer #5 · answered by Anonymous · 0⤊ 0⤋
it's being proven that forward time travel is possible with atomic clocks i.e. two atomic clocks, one on a plane and one on the ground. the plane takes off and circumnavigate the earth and lands beside the stationary clock. both readings are taken, the planes atomic clock reads 1/100000000 second slower. hence the stationary clock age more than the planes clock. (check out the Hafele and Keating Experiment using Einstein theory of relavitity). another interesting fact is the artificial satelittes that are sent into orbit have to get there on board timers reset every year by .02 of a second faster because of time travel due to the speed of the satelittes throughtout the year.
of course you would need to travel a lot faster than a plane or a satelitte to get more noticable time differences. such as near light speeds.
as for travelling backwards in time is theorectical possible however you would need to travel faster then the speed of light. of course this would mean ignoring or breaking the laws of physic that we understand today. another idea is to use wormholes.
There are two main kinds of time travel paradoxes. The first type involve changes to the past (Grandfather Paradox), the second involve what are known as “causal loops. the site below goes into a lot more detail than i can with ANSWERS.
please read up on the two paradoxs, it would seem that backwards time travel is impossible because of the paradoxs.
Quantum theory however suggest that it is possible without causing paradoxs. if you did manage to go back in time and change it (eg you kill your grandfather) you would split the timeline into two, the one we are in now and the one you went back and change. the same would happen each time you went back. these alternative timelines could possible be parallel dimensions.
so if they are time travellers to the past we will never see them, because they would split off into a different timeline/dimension
ps look up professor Ronald Mallett, he's trying to invent a time machine.
2007-03-15 17:30:29 · answer #6 · answered by sycamore 3 · 0⤊ 0⤋
your question is more one for metaphysics than physics.
to understand this puzzling concept at least partially, you must accept that there is no objective past present or future. only it exists separately with each conscious being.
in short, i am saying that the past present and future are perceptions in your mind only.
in effect, it is impossible to travel in to the past because it is like traveling into a person's memories ( and that is what the past is ---memories only -- it does NOT exist physically )
the future does not exist also, BUT , its has the POSSIBILITY of existing. ( an important difference because we CAN travel to a potential destination ! )
that leaves us with the present which is the only real entity but one that has as many versions as there are conscious sentient beings in the universe !
to answer your question, time travel to the past is meaningless. future travel is possible.
so enjoy the NOW !
good luck : )
2007-03-13 14:26:59 · answer #7 · answered by fullbony 4 · 0⤊ 0⤋
One possible answer for this is based on the Sum of all Histories theory. If someone were to time travel, they would be traveling not only into another time, but another spacetime--i.e. a parallel universe where the events the traveler caused were part of that universe's normal history.
So, in the universe you were born in, you are part of its history and part of it until you leave it to travel to another spacetime where someone matching your description went and found THAT universe's version of your parents and killed them. And, in THAT universe, its history reflects your parents dying before they had any child like you. So, no paradox at all.
There is nothing you could do in THIS universe to prevent you parents from meeting and having you as a child.
Our destiny/history can never be altered in the overall picture of this universe. Events that happen, have always happened and will always happen for any history of this universe, no matter who has come into it or left it.
2007-03-13 06:38:16 · answer #8 · answered by quntmphys238 6 · 0⤊ 0⤋
There are several ways you could possibly time travel some easier than others. on way is if you could create a worm hole then electrically charge one end and take it on a long space ship ride and when it returnes there will be a time differential between the two ends so you could go in one end and go back in time and go in the other way to go forward in time.
another way is by jumping to an alternative universe in the past and then you can kill you grandad all you want as hes not from your universe. or you could travel very fast in a circle near the speed as light but u will require half the mass of the universe to do this. or easier you could send data back in time but only to the time you first made the machine and you could send your self the lottery numbers but you would probally think its aliens trying to contact you. either way if you do find a way to go back in time then can you burry a ton of gold in my garden lol.
2007-03-13 09:19:24 · answer #9 · answered by Richard 1 · 0⤊ 0⤋
A funny one...i used to mull over this myself and came to the conclusion that if time travel really does exist, then those who travel would not be able to be visible/have certain restrictions on them- otherwise they'd be here and now and someone would have known about it. Even the most trusted time travellers that start in the beginning, may keep to their word and remain secrect and anonymous, but surely those many years later (e.g. those paying to go back in time, like those paying to go into space) would slip up at some stage?? I dunno. This is all if the planet doesn't implode before time-travels discovery!
2007-03-13 06:32:39 · answer #10 · answered by Me-o 2 · 0⤊ 0⤋
Yes if it is possible then maybe they already have but we wouldn't know about it. And yes if time travel is possibe in the future then people can travel through time in the future to the future also.
For more detailed discussion on time travel check out the link below.
2007-03-13 06:32:35 · answer #11 · answered by Girugamesh 4 · 0⤊ 0⤋