h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

In life something only happens once, and when it has happened it will not happen again.
(Something may happen two times for you, but all particels in the univerce don't happen to be att the same place two times at the same time as all the others)
That means that sooner or later (sooner i hope) all diffrent possibiletys have happened, and then time ends, or start going backwards.
If this is true then we have to do everything that we do now once again, but vackwards.
Is'nt that a kind of timetravel?

What an interesting situation! You must exist in a sea of neverending appointments (that is, if you have any at all...) separated by intervals of zero time (usually the way my work day goes).

No! He meant the time between being ready for the appointment and the appointment actually starting.

I think time travel is possible only when one can get out of the four dimensional world we live in. The three spatial dimensions and the fourth time dimension are fixed (Einstein has shown this). If we would succeed in changing one of the dimensions, we would destroy the whole fabric of space/time. Consequence : the world as we know it would stop to exist. End of discussion as far as I am concerned.

I don't think Einstein showed this at all. In fact, some solutions to Einstein's equations of General Relativity do allow for the possibility of time travel, without any rupture of the spacetime fabric. There are time travel paths near the event horizons of massive rotating black holes, for example.

Excuse a lay person commenting, but if time is a dimension, it must share characteristics with the other three dimensions. So you must be able to move from A to B in it (other than the ordinary passing of time, over which we have no control)

But this is just a question of definition and not an attempt at anythíng to do with physics.