One of the leading researchers in time travel, William A. Hiscock, a professor of physics at Montana State University. Here are his thoughts on the matter:
“Is it possible to travel through time? To answer this question, we must be a bit more specific about what we mean by traveling through time. Discounting the everyday progression of time, the question can be divided into two parts: Is it possible, within a short time (less than a human life span), to travel into the distant future? And is it possible to travel into the past?
“Our current understanding of fundamental physics tells us that the answer to the first question is a definite yes, and to the second, maybe.
“The mechanism for traveling into the distant future is to use the time-dilation effect of Special Relativity, which states that a moving clock appears to tick more slowly the closer it approaches the speed of light. This effect, which has been overwhelmingly supported by experimental tests, applies to all types of clocks, including biological aging.
“Time travel into the past, which is what people usually mean by time travel, is a much more uncertain proposition. There are many solutions to Einstein’s equations of General Relativity that allow a person to follow a timeline that would result in her (or him) encountering herself–or her grandmother–at an earlier time. The problem is deciding whether these solutions represent situations that could occur in the real universe, or whether they are mere mathematical oddities incompatible with known physics. No experiment or observation has ever indicated that time travel is occurring in our universe. Much work has been done by theoretical physicists in the past decade to try to determine whether, in a universe that is initially without time travel, one can build a time machine–in other words, if it is possible to manipulate matter and the geometry of space-time in such a way as to create new paths that circle back in time.
