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On the impossibility of Time Travel!

I promised the occasional philosophical reflection on this blog. Here's one:
If I 'travel' 'back' into the past, then I am there in the past.
BUT, in my past, an older version of me wasn't present, anywhere. Therefore,
one cannot travel back into the past: for, if one travels back into the
past, IT IS NO LONGER ONE'S PAST that one is travelling back into...

Comments

Anonymous said…
But what if travelling back in time in fact opens up a parallel dimension, where the past exists separately? Is there any scientific fact to that oft-repeated science fiction convention that the same material cannot co-exist in the same space (or something) so if you touch your older or younger version you explode?
27 March 2009 at 18:27
weggis said…
You are merely playing with linguistics, and not the practicalities of the possibility.

If one travels back in time, the present becomes your past.
27 March 2009 at 22:28
Green Gordon said…
Just as you can move through three dimensions in space, you can move through time, but as it happens, generally only at forward at the normal rate.

The word 'past' is relative to the present.

In absoulute sense, though the past is just the same place regardless of how many of you are in it. It's a bit like saying if you go to Brussels, you can't be in Brussels because you are not currently in Brussels.

(did I just repeat Weggis with far too many words?)
28 March 2009 at 10:31
Rupert said…
Rayyan: If 'travelling back in time' opens up 'a parallel dimension', fine - but then it's not THE PAST.
The fantasy of travelling 'back' 'to 1851' [or whatever] is therefore: merely a fantasy. Any 1851 that one 'travelled back' to would not be OUR 1851 - and that is what one wanted to 'travel back' to.
All: As my deliberately laboured scare-quotes signal, the underlying problem here is the delusion that one can model travel 'through time' on travel through space. The grammar of time and of space are DIFFERENT from one another - you are all failing to recognise this. For detail, consult my book, APPLYING WITTGENSTEIN - The section on time... ;-)
29 March 2009 at 09:04
weggis said…
Rupert,
What you seem to be saying here is that because the grammar of our language does not accommodate time travel then it is not possible. That is Bx.

Our language has developed to describe time [and space] as we have experienced it so far. If we begin to experience them in other ways then our language will have to develop to describe those phenomena, just as it has developed to describe a whole bunch of other stuff.

Wittgenstein said: “The limits of my language mean the limits of my world” He DID NOT say that we cannot find new ways to express, understand and communicate new ideas, experience and discoveries, otherwise we would not have made any technological or scientific progress at all.
29 March 2009 at 13:03
Rupert said…
Weggis: I might just as well have said: "Because the grammar of our language does not accommodate sdlfhjdsfg, then sdlfhjdsfg is not possible". Because that is true. Because sdlfhjdsfg is nonsense. And so is time travel. What my argument proves is that it doesn't MEAN anything to talk about time travel. Just as it doesn't mean anything to talk about sdlfhjdsfg.
18 April 2009 at 21:25
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