Fuddland

At the risk of making a fool of myself in front of the slowly-growing band of physicists that occasionally read this weblog [I think we’re up to four now], I’m going to pick a hole in this new theory about time travel. Or rather, in the way that the BBC has reported it.

The main headache [with usual notion of time travel] stems from the idea that if you went back in time you could, theoretically, do something to change the present; and that possibility messes up the whole theory of time travel.

Clearly, the present never is changed by mischievous time-travellers: people don’t suddenly fade into the ether because a rerun of events has prevented their births—that much is obvious.

I’m disputing this “obvious” claim. What’s happened to the idea of parallel universes? Has that been empirically disproved? I thought the theory was, if you do somehow go back in time, say precisely 10 years, and change an event that had occurred in your past, this instantaneously creates an alternative universe in which you now live. So if you go forward in time 10 years from this point, you don’t land back where you left, but instead are 10 years hence in this new universe. [Have these people never seen Back to the Future Part III?] It seems to me that, if parallel universes exist, they eliminate the possibility of people disappearing “into the ether”, because in one universe someone can live to a ripe old age, whereas in another the “same” person might die younger.

[This is all nonsense of course. I’m pretty sure that I believe in neither time travel nor parallel universes. If I get drunk enough I might write about my theory about how waiting for a bus disproves that time travel will never be discovered by humans…]

#1

highrise | 2005 / 06 / 19 – 19:33

I love the Many Worlds theory; that it’s not just one alternate universe which is created at the point of making a choice - but many (or however many possible choices you could have made) Anyway, I’m fascinated by the possibility that one might skip between universes one has created.

[Edited by commenter — 18:36]

#2

David | 2005 / 06 / 19 – 19:37

Re #1: The creation of many universes based on the number of possible actions at any given time seems, to me, to be overly wasteful; it only seems “necessary” to create a new universe when the current timeline has been altered. [Hmm, I’ve been watching too much Doctor Who!]

[Edited by commenter — 18:44]

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