MN Physicists and Philosophers, I have some questions about time travel.

[Slubberdegullion]

Watched Donnie Darko for the first time yesterday, which led to conversation with DH about the possibilities of time travel and alternate universes, which led to wakeful period at 3am with head full of questions.

Anyone here care to have a stab at answering (in a simplistic manner, I did not do very well at A-level physics) some of my questions?

Have you read the The Time Travellers Wife?

Um, I think I can see the line, because I'm not in time. Right?

I have read the Time Travellers wife.

Well, in basic terms, an intra-universe wormhole is a compact region of spacetime whose boundary is topologically trivial but whose interior is not simply connected.

So, for example, if a spacetime contains a compact region X, and if the topology of X is of the form X ~ R x Y, where Y is a three-manifold of nontrivial topology, whose boundary has topology of the form dY ~ S², and if, furthermore, the hypersurfaces Y are all spacelike, then the region Z contains a quasipermanent intra-universe wormhole.

Well, I haven't, Window, but I will look out for it.

Slubber, if you're really interested in this, then can I direct you to this book:

A New Model of the Universe.
P.D. Ouspensky.

This is not a modern book, and you will need to order it. His chapter on the Fourth Dimension is well worth the price.

lapin, please please tell me that was copied and pasted.

If you were a bird, looking at the line of history, you would be able to see it all. It's only when you're on the paper that you can't see it.

It's dimensional, and totally incomprehensible If you could truly understand it, I doubt that you would be capable of living a normal life.

But it's hugely fascinating.

DP has regaled me many a time with his theories on space/time travel and folding space.

I'll pass on folding space. I struggle with the deck-chair and the map!

No, it's just a subject I'm interested in.

OF COURSE it was C&P!

The point about people coming back to tell us about time travel - a) perhaps they would need to return to a time when science/technology is sufficiently advanced to even comprehend the concepts they would be expounding, and b) there is the theory that by interacting with the past you cause changes that could have dreadful and/or far-reaching consequences. It's a bit like the whole Schroedinger's (sp?) Cat thing.

So you can only view the time line, or live in it, not both.

DH was telling me over dinner about the time travellers paradox (HG Wells?) that either you can time travel with free will, but risk causing a change in history that brings about your non-existance.

Or you travel, and everything follows along neatly (you do not cause your own extinction) which indicates that everything is preorodained, you have no free will.

This is why SciFi writers struggle with time travel because they don't like to imagine a world with no free will.

(my brain was hurting also by this point in the conversation).

I have been watching Heroes on BBC2 and even the time jumping there has confused me

DP's theories on folding space or bending it are fantastic. They certainly cure my insomnia.....

I jest....he's a blardy intelligent man. It makes me wonder why he didnt get anywhere with it.

everyone knows that all the information on wormholes is locked in Ben Browder's head

Cappuccino I know er that series. They said Frell all the time.

Oh, and cappo - I'm nominating

By CappuScreamO on Mon 29-Oct-07 16:30:43
this is the problem with these art films

you never stay awake pondering Die Hard

for quote of the week

Farscape.

yes Farscape

now all the answers you need will be there

(ooh VVV you have made me )

Funnily enough - I've just posted your quote on the Quote of the Week thread, and seen a post of yours on the 'biro on dolls head' thread and PMSL!!!

Well, Dr Who time travels all the time, and he has a very good complexion for it

It is true that if you travel in space, you age less quickly. So, from that factual premise, it must follow that time is, to some extent, an illusion.

A human, earthly invention. After all, it's only an hour because we way it's an hour.

And if time is an illusion, than surely to travel within it is plausible?

Most people (myself included) struggle to grasp three dimensions. The fourth dimension, for most people, is unobtainable. And for those who do obtain it, they drop out of sight. We shall never know.

Surely that is down to gravitational influences and abundant free-radicals (re ageing)?

[self-confused]

Yes, it is due to the lack of gravity in space.

But that still doesn't address the issue of time. It seems to exist on earth, but not elsewhere?

Oh, I'm getting SO tempted to break the code of science and tell you all what happens to MN in the future

I don't actually use a laptop, you know... I beam my thoughts to a little chip in my cerebral cortex and I see a retinal image of the board. (Not quite sure how that explains the occasional typo )

Desi - how do we know it doesnt?

Oh, God. I've just realized something.

Lapin is naught more than a brain in a demi-jon.

She's 5ft 1". 4ft 5" of that is a stool [sad}

Desi!

How did you know!

Well, VV, we don't know it doesn't. But our concept of time is based on earthlings rationalizing the space between the moon/sun/earth cycles.

Since no other planet has earthlings, or similar cycles, it's reasonable to assume that, for instance, a mythical Martian's concept of time would be very different from ours.

et voila! and