Is Time Travel is Possible?

["Bernie Doeser" <bernie@doeser.org>]

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There are a number of problems and paradoxes with the concept of time
travel, which favour the argument against it, which I don't think have been
raised so far.

Firstly - if an object, with mass, travelled from time A to time B, then the
mass of the universe would be reduced by the mass of the object for the
period of time between A and B. This would seem to contradict one of
Einstein's theories that matter cannot be created or destroyed.

Secondly - there are no known mechanisms for time travel. Accepting that
your internal time slows the nearer you get to the speed of light, it is
theoretically possible that you could fly in a rocket and return in eighty
years time, with only five years on "your" clock. But is that time travel ?
I think it is not what most people mean by time travel, which is what
happened in the "Back to the Future" films. Dial a date, press a button, and
fall in love with your long dead great great grandmother. Time travel in
it's common understanding involves a discontinuous travel backwards or
forwards in time. No mechanistic theories come close to explaining how this
might happen.

Thirdly - for time travel to be possible the past and the future have to
exist. We know that the past existed - we remember it, but we do not know
that it continued to exist after we experienced it. There is an inherent
assumption in time travel that the past and the future exist continuously,
and we are merely passing through it. The determinists will argue that the
future already exists, that it is unchangeable, and that we have merely to
experience it. As philosophers we know this poses problems for free-will,
personal responsibility etc etc. So therefore time travel is inconsistent
with free-will. There is an interesting twist when you extend this thought
experiment. If the future already exists and we travel to it we would be
changing it (by our presence) which would mean that it exists in a different
form after we travelled to it than before. Therefore the future changed and
so could not have existed.

Finally - If the past does exist, and someone has travelled back there, then
someone has already time travelled, and there is a record of it in the past.
But as there isn't, we haven't. The conspiracy theorists would say that time
travellers would be ultra discreet. Personally I think they'd have bought
out IBM, Standard Oil and Microsoft.

Bernie Doeser
Sandiway, Cheshire, UK.






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