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Still not enough power...

mmalky

No, time travel is not possible at this ‘time’. When it does become possible it will be travel only into the future but never into the past. One of the answers alluded to the violation of the conservation of mass that would occur if we went into the past. This is something that cannot be ignored.

But, the future does remain open. I am sure you are familiar with the story about the twins, one of whom goes on a trip and the other stays behind. The one who goes on a trip travels at a significant percentage of the speed of light. In so doing time for him proceeds more slowly relative to his twin that stayed behind. When the traveling twin returns he finds his brother much older than he is.

Let us add your wormhole to this scenario. Suppose a worm hole was made from your house to, say, the local airport. After all, if wormholes can be made in space then can be made anywhere. And if they can be light years in length they can also be merely miles in length too.

If the traveling twin were to attach the airport end of the wormhole to his rocket ship and drag it with him on his trip, including his return trip then . . . .

Remember that the twin returns to Earth at some time in Earth’s future. Suppose he lands at the airport and calls you to come and get him. You will not find him there because he is in your future! The only way to meet him is if you go through the wormhole from your house to the airport, only now, the other end of the wormhole is not only in another place, it is also in another time!

Can you think of some paradoxes that would arise because of this?

The equations describing time show that a clock travelling close to the speed of light will be slower than clocks that are at rest. As you get to the speed of light, the clock will stop as the rest of the universe will keep on ticking. The equations also show that as you get faster than the speed of light the clock will go backwards. Unfortunately you can't accelerate to the speed of light due to the increase in mass. There may be a loophole, if you could jump beyond the speed of light without slowly creeping up on it.

Right now, the only time travel we can expect to be real is towards the future, at a rate that can be modulated by going to a speed close to the speed of light.

Going back in time would mean that yesterday's universe would have additional mass coming from the future -- among other violations of what we think we understand of the laws of nature -- and we cannot make that fit in the big theory of science.

Technically it already has been man made.

Just think about the CERN particle accelerator. With the electrons/ atoms moving at 99.9999% (or however close to "c") the time dilation induced (or the gamma factor) is massive. Those particles have effectively moved forward in time.

The same would be applied to us, maybe we one day we can invent close to light travel. (BUT NOT LIGHT TRAVEL, I hate when people say that :P )

But going back in time?

The unrelentess march forward of time is the only real constant in the universe. So no changing the past!

Another person totally unaware that he IS traveling through time right now at a rate of one second per second. Why do people always resort to wormholes, black holes,teleportation through time, either accidentally or on purpose- with a "time machine," when the best time machine is the one in your head - your imagination.

"The short answer is that time travel into the future is not only possible, it's been done, and we've known about it for over a century," says Davies. "The reason that the public doesn’t seem to know about it is because the amount of time travel involved is so pitifully small that it doesn't make for a 'Doctor Who' style adventure."

A phenomenon called time dilation is the key here. Time passes more slowly the closer you approach the speed of light -- an unbreakable cosmic speed limit. As such, the hands of a clock in a speeding train would move more slowly than those in a stationary clock. The difference would not be humanly noticeable, but when the train pulled back into the station, the two clocks would be off by billionths of a second. If such a train could attain 99.999 percent light speed, only 1 year would pass onboard for every 223 years back at the train station.

"Time runs a little bit faster in space than it does down on Earth," Davies says. "It runs a little faster on the roof than it does in the basement, and that's a measurable effect."

A clock aboard an orbiting satellite experiences time dilation due to both the speed of its orbit and its greater distance from the center of Earth's gravity.

"Both gravity and speed can give you a means of jumping ahead," Davies says. "So in principle, if you had enough money, you could get to the year 3000 in as short a time as you like -- one year, one month, whatever it takes. It is only a question of money and engineering."

Forward, not back

Time travel into the future is an established and fundamental aspect of Albert Einstein's theory of relativity. Scientists have tested and retested this in both experimental and practical settings. But what about time travel in the opposite direction?

"Going back in to the past is a whole different kettle of fish." Davies says. "There's nothing in Einstein's theory, which is the best theory that we have about the nature of time, which precludes it. There's nothing in even his general theory of relativity, published in 1915, which precludes travel back into the past, but many scientists are deeply uneasy about it because of all the well-known paradoxes that it unleashes."

For instance, imagine going back in time and killing your own mother. Then she'd never give birth to you, and just how would you have been able to travel back in time to commit matricide in the first place?

Wormholes as spacetime shortcuts

Davies surmises that, given our current understanding of the nature of time and physics, time travel into the past simply isn't possible. But the universe is full of mysteries, and one of them -- the hypothetical wormhole -- might just permit such a journey.

"This is a little bit like a tunnel or shortcut between two distant points," Davies says, "So for example, if I had a wormhole here in my hotel room and I jumped through it I wouldn't come out on Pennsylvania Avenue, I'd maybe come out near the other side of the galaxy."

Scientists have theorized that such a shortcut through time and space could be turned into a time machine.

"If a worm hole could exist and could be traversable, then it would provide a means of going back in time," Davies says. "So it all hinges on whether stable wormholes are a reality or if there's some aspect of physics -- not relativity, because there's nothing wrong from that point of view -- but some other aspect of physics might intercede and prevent the wormhole from forming. That's an open question."

World-famous theoretical physicist Stephen Hawking has proposed that wormholes occurring at a quantum level could theoretically provide a foothold for time travel, but University of California at Santa Barbara physicist Andrew Cleland urges caution on that front.

"I'm an experimentalist, and physics is ultimately an experimental science," Cleland says. "Any predictions that are made based on mathematics or on philosophical or intellectual speculation have to pass the test of experiment, and I am certainly not aware of any experiment that demonstrated the possibility of traveling backward in time."

Cause and effect

Cleland also points out that the fundamental principle of causality stands in the way of travel into the past. The entire universe, as we understand it, is beholden to this rule.

"Something occurs first and the outcome of that occurrence happens afterward," Cleland says, "and there has never to my knowledge been an experiment that came out different from that. I am not aware of any experimental tests of quantum mechanics that have shown any violation of causality, in spite of the fact that many experiments could reveal such a violation."

"Theoretically, it would take more than 100 years to create a 100-years' time difference between the two ends of a wormhole," Davies says, "so there's no way that our descendants could come back and tell us we're wrong about this."

I was a big Christopher Reeve fan and in one of his movies time travel was not only possible it did not require any power or machine or going anyway. It just required a very firm belief. That is a very wild idea, but an interesting movie. It's a fantasy romance time travel story...very unusual. If you like that stuff, you might like the movie.

Somewhere in Time: http://www.youtube.com/watch?v=8_JmUMkLy7g

Mathematically, and staying with the laws of physics as we know it, yes, however...

The practical application of sending a human (or anything other than digital information) would require the event horizon of a black hole, and that is almost so unlikely for us to achieve it might as well be considered impossible.

Of course it is. You, me, and everyone else travels forward in time by 24 hours every day.

If time travel were possible you would already know it.