Are time machines possible? (Intermediate)

Is going back in time really possible? If so, would we have the resources to do it..say 100 years from now?

It may be, it may not be. The laws of physics that we know about don't seem to forbid it. The easiest way to do it would be with a worm-hole, a sort of "short cut" from one part of the universe to another. There are ways (in principle) of creating a worm-hole with one mouth in the present and one mouth in the past, so that if you went through it, you would be travelling back into the past. There are reasons to believe, however, that such a wormhole would be unstable. The matter is still very undecided. In any case, you would not be able to go back and change recorded history, since everything you do in the past must be consistent with the state of things in the future. Nor could anyone come back from the future to the present period, because you can only go as far back, using this method, as when the wormhole is first created. We also would not have this technology (if it is possible at all) for many thousands of years, I'm sure.

This page was last updated June 27, 2015.

About the Author

Dave Kornreich

Dave was the founder of Ask an Astronomer. He got his PhD from Cornell in 2001 and is now an assistant professor in the Department of Physics and Physical Science at Humboldt State University in California. There he runs his own version of Ask the Astronomer. He also helps us out with the odd cosmology question.

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