Thursday, 13 June 2002
Will time-travel be possible through worm holes in space?
Paul Davies has just written a book on ‘How to Build a Time Machine’, so
Robyn Williams took a train ride with the author to find out just what
confronts science when it comes to time travel. It turned out that by
just riding a train they were already moving forward in time by nano
seconds. The real challenge is how to go back in time, and to do that
you need a black hole. But don’t despair, because as Davies explains –
theoretically it’s all possible.
Full Program Transcript:
Prof Paul Davies
Adjunct Professor of Physics
University of Queensland
Robyn Williams: Paul I want you to make me a time machine so why
have you brought me on a train?
Prof Paul Davies: Well a train was actually Einstein’s original
idea for a time machine. When he published his theory of relativity in
1905 that was the pinnacle of technology.
Robyn Williams: But trains are always late.
Prof Paul Davies: Well maybe in 1905 they ran on time. But the
principle is very simple. Einstein recognised that simple motion would
transport you into the future. Now travelling on a train doesn’t do it
in very exciting amounts. We are actually travelling a little bit into
the future of the people standing out there on the platform and in their
houses but not an amount that you or I would notice. However with modern
atomic clocks, which are fantastically sensitive you can detect the time
warp factor. For example in airliners fly a clock in a plane around for
a few hours, come back and compare it with its clone on the ground and
it would differ by a few billionths of a second. So still not enough to
make an adventure but enough to measure and there’s no doubt whatever
that you can travel into the future by moving. Now if you want to go a
long way into the future you’ve got to move very fast.
Robyn Williams: What if this train went at the speed of light for
Prof Paul Davies: Well you can’t actually reach precisely the
speed of light but you can get in principle very, very close and the
closer you get the more time is warped. So you can imagine say getting
in a fast rocket ship going off to a nearby star at close to the speed
of light and maybe for you the journey would take one year and when you
got back everyone would be ten years older. You would have effectively
jumped nine years into the earth’s future. So it’s a great way to travel
into the future, the problem is you can’t use this method to go back
into the past.
Robyn Williams: I still actually want you to make me a time
machine. How would you do it?
Prof Paul Davies: To travel into the past as well, now that’s the
trick. Getting into the past is theoretically possible but likely to be
extremely expensive. Now there are various proposals around but the one
I prefer uses something called a worm hole in space. What is a worm hole
I think you’re going to ask me. Well everyone’s heard of black holes. A
black hole is a one way journey to nowhere. They suck things in and you
can’t get out again. You effectively hit the end of space and time if
you fall into the middle of a black hole. A worm hole is like a black
hole only a bit different. It’s on an exit as well as an entrance. But
the worm hole is a little bit like a tunnel or a tube that would connect
two points in space in such a way as to make a short cut. So if you had
a worm hole in your living room you might be able to jump in and a few
moments later come out on some distant star.
Robyn Williams: So what would it look like floating there in my
Prof Paul Davies: Well it would look just like a window, probably
a round window and you’d look through it and instead of seeing what is
outside your house which is a large building site you’d see the details
on some distant planet maybe where the other end of the worm hole is
Robyn Williams: So you could see where you were going?
Prof Paul Davies: Yes that’s the whole idea because it’s got an
entrance and an exit but to use it as a time machine you’d probably want
to have the two ends them rather close together so we would jump into it
in your front room and maybe come out in your back room the day before
or the year before or maybe ten years before.
Robyn Williams: Is this time travel idea useful in any way at all?
Prof Paul Davies: The whole idea of time travel into the past at
least is obviously a very theoretical one but it does have its useful
side as well, its serious side because after all science is supposed to
give us a consistent picture of reality and if it turned out that we had
a set of physical theories that led to genuine paradox we’d have to
reject them so it’s a sort of test thing to our fundamental physical
Robyn Williams: If we did get one of these time machines would
you travel in it yourself?
Prof Paul Davies: I think I’d send the cat on ahead first just to
see how it got on.
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