Will time travel ever be a reality?

Answer 1

Suppose you wished to "travel" into the past. What a person would need to know is, where are we at present and where do we wish to go.

Presently each of us inhabits a very narrow band of reality. The segment of physical reality we inhabit is that bit of physical, real time that exists between the past and future. The duration of this time is thought to be that of the diameter of the electron (or a complete wave). It is called the Chronon.

Were you to wish to move into the past you would have to leave this very narrow band of existence. Which, if it were done, then all other physical reality about you that we call our universe would disappear. Where you would actually be no one could know, and due to the nature of the movement of our planet, it likely would never be the same place twice.

That isn't the worst of the problem though. If you wished to meet a person who lived at any time in the past, the physical particles that formed their bodies are not in some other physical place. They exist here in our "present" time. The material has just fallen into dust and ashes, but the person's body exists with us today.

It is the same if you wished to visit a person of the future. There would be nothing to visit because the body that shall be in the future is here in the present. It just hasn't been put together yet.

Lastly, suppose there were a way for you to move outside "present time" and move into the physical past. Would you wind up appearing suddenly inside our sun, our planet, or on another planet, perhaps in another part of the universe? There are no directions, and if it went wrong it would all be a one-way trip with their being no whitnesses.

Answer 2

Larry Niven, the noted s/f author, has done a series of lectures on the topic at MIT, gathered under the title The Theory and Practice of Time Travel.

His conclusion is that if time travel is eventually possible, then there will be time travelers from the future eventually trying to change the past. Eventually, there will be enough change, so that it (prevents) makes time travel impossible. hence: no more time travel!

Or, there may be a 'historical inertia' such that no matter how much we change, history 'heals' and the changes are absorbed and nothing really changes.

Or, if there is any meaning or truth to 'cause and effect', the universe will resist being changed. Entropy and coincidence will act to prevent time travel from occurring. This is how he codified it:

"Niven's law: If the universe of discourse permits the possibility of time travel and of changing the past, then no time machine will be invented in that universe.

"Bothered by smog...? Henry Ford could be stopped in time, in time....

"No. We face insecurity enough. Read your newspaper and be glad that at least your past is safe.

For myself, I prefer C. S Lewis' view of time travel: We are all time travelers, moving into the future at the rate of sixty minutes an hour.

After all, if we cannot use the time we have been given wisely, of what use would more time be....?

Answer 3

Currently, "time travel" to the future is a distinct physically possibility. However, as of now, it is impossible to "go back" in time. This of course is due to the fact that the speed of time is related to the direction of speed in space-time.
Under Einsteinian physics, everyone is travelling at the speed of light, but part of that speed is in four directions: up/down, forward/backward, left/right, and time. The faster one goes in any of the spatial dimensions, the slower one goes through time. So time passes slowly for that person compared to someone at rest. For the person travelling very, very close to the speed of light, it will appear to him that he has indeed ended his journey in the future. However, this is not "time travel" as we have all invisioned. In essence this is the same thing as just leaving a room, standing outside of it, then entering again, claiming you leapt into the future.
Going back in time seems to be very unlikely. The fourth dimension, time, seems to have a very curious parameter: ONE WAY. That way is forward as we see in daily life. There is one way where time travel may be possible: a wormhole.
A wormhole is very difficult to visualize, especially when we use it as an extra-dimensional path in a four-dimensional world (humans can envision no more than three dimensions). I'll try to make a reasonably simple explanation.
Imagine you are trying to go over a mountain. You can only travel along the surface, right? No one can walk through mountains. The surface of the mountain is roughly a cone. So you'd be taking a rather curvy, arduous trip. But what if there were a tunnel? The tunnel isn't on the surface of the mountain; it simply links two very separate portions of the surface by a much shorter route. The tunnel is a wormhole.
Now just try to expand that image up by a few dimensions. A wormhole can lead from one time to another or simply from one side of the universe to the other. The trick to a wormhole is that it is not simply a tunnel through a "mountain" of space. It is a tunnel that connects two areas of space by going throught nothingness. And by nothingness, I mean nothingness: no space, no dust, nothing.
So in theory a wormhole can help us to travel through time. Question answered, right? No. I'm afraid it gets a little more complex.
Currently, cosmologists ( a kind of physicist that studies the universe as a whole) a theory on which they pretty much agree about wormholes. The problem with wormholes is that they aren't stable. Singe atoms would be lucky to make it through a wormhole before it disintegrated. How would it be possible for a human space ship to go through?
The answer: Exotic matter.
Most people think of matter and only think of the matter all around them. However, we know that there can be different kinds of matter. Such as dark matter and exotic matter. Theoretically, dark matter should make up the majority of matter in the universe. But, since no one really knows what it is, we can't look for. And since we can't look for it, we can't really find. And since we can't find, we don't really know what it is.
Exotic matter is something completely different, yet oddly the same. We don't know what it is. We know that it is, but that's about it. (Don't worry. The tangent is over now.)
Exotic matter can be used to stabilize wormholes. For some reason, exotic matter acts as strucutral support for wormholes much like wooden beams, one sees in mines. These could temporarily stabilize the wormhole. However, it is currently believed that exotic matter itself is somewhat unstable. So the stability could easily fail and the wormhole disappear.

All things considered, "time travel" as seen by Americans that have lived within the past fifty years, is simply fiction. Some new technology may emerge, however. But I feel this is an unreasonable effort.

Answer 4

On a purely philosophical level, we are timetravelling at the moment, one second (or smaller intervals if you prefer) at a time, into the future.

As to travelling back in time (or forwards faster than this), this seems unlikely at present IMO.

Answer 5

give it about another 100 yrs and the US and japan will get it. If the work together. If not it will never happen.

Answer 6

hopefully not