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The Question
(Submitted March 26, 1997)
Can humans go back or forward in time ( in the future )?
If yes then how?
The Answer
An interesting question....can humans travel back and forward in time. I
presume that you are asking about travel in time like you see on
television or in the movies. But let me take a more scientific (if
simplified) approach.
The laws of science do not distinguish between the forward and backward
directions of time -- yet they do distinguish the past from the future
(time increases as disorder increases). There are some solutions to the
equations of General Relativity which would allow for travel back and forth
in time....(1) would require that you move faster than the speed of light,
but we know that this cannot be done; (2) would require space-time to be very
warped and a sort of "tunnel" between two space-time points to be present
(called a "wormhole"). Such tunnels would not last long enough on their own
for anyone to travel through them (unless the traveler discovered some way
or built some machine which would keep the tunnel open). There are all sorts
of other conditions which would have to be imposed on space-time in order for
human beings to travel into the past. All of these conditions tend to conspire
against time travel being more than a theoretical possibility.
But, as of 1997, our understanding of physics causes the possibility of time
travel to remain an open question. NOTE: What I have said here is related to
big objects like humans...and my comments do not necessarily apply to very
small (subatomic) objects.
Hope this helps,
Laura Whitlock
for Ask an Astrophysicist
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