multiverse theory

[snas (Stuart)]

If we accept the theory of multiple universes in which we all lead varying different lives; in this universe I am a vet, in the universe to my right I am a truck driver, in the one on my left I am so wealthy that I can just spend all of my time surfing the best surf breaks woo hoo, sounds great to me); my question is, how do I get to exist in these other universes? After all, if I can have different jobs and standards of living in other universes, what's to say that my father (at least, the man who is my father in this universe) never met my mother (in the universe to my left) and therefore married someone else and therefore I would not exist in that particular universe. Surely when (some) people write about us living all of these different lives in different universes, they haven't considered that even by changing something like who my father married they have then changed who comes along in the next generation. Of course, if something in that generation was different one generation ago, surely things may have been different on the "earth" of that universe such that life never arose or that life did arise but never resulted in us being there.

Of course, the big question is, how do I find my to the universe to my left (the one where I surf all the best breaks? A free quiver of boards and a lifetime supply of surfboard wax to the person who can get me there. Hmm, will the beaches be populated by lovely young ladies, the reefs covered in latex and the sun never burn? (come on now, this is a VERY serious question)

Stuart

[adman (Adam)]

I might be wrong (and frequently am) but every time there is a 'choice' the universe splits into 2 distinct wave functions - but only if there is no observer. Once an event has been observed, the wave functions collapse into the 'reality' of what actually happened. Of course it depends on what you call an observer (and what you call reality for that matter). In the thought experiment with Schrodinger and his imaginary cat, to the person outside the box, the universe split into 2 possibilities - the cat is both alive and dead. But is this the case for the cat? Is the cat, as an observer, able to collapse his own wave functions?

From this I think that once humans make a decision, it has already been observed, and there is no split. So no perfect point breaks, no huge bank account, no nubile beauties. I don't think that all the possible versions of you exist in parallel.

Adam

[avandonk]

In an infinity of possible parallel Universes everything has already happened. You are just living one possible time line.

This is all conjecture.

Enjoy while it while you can.

Bert

[Dave2042 (Dave)]

Interesting question. My perspective is in context of physics honours about 20 years ago.

Your last question seems to be premised on a very deep and widely misunderstood issue, which I'd paraphrase as 'where is the universe'. Simply, if the universe is 'somewhere', then obviously all these other universes are 'somewhere else' and so you should be able to go to them, somehow.

I think this is related to how people often think of the 'geometric' view of General Relativity (which I seem to recall Einstein didn't like). This describes space-time as 'curved', begging the question of what is the straight thing that it is curved with respect to. This seems to imply again that the universe is 'somewhere', sitting in a flat background place, being curved against it.

All this is of course supported by our day-to-day intuition that all 'things' are 'somewhere'.

In fact (as far as we can tell) the universe is not anywhere. There is no outside or background or 'edge' you might eventually run into, or place you might stand and point to the universe. As to the geometric interpretation of GR, this is really only a useful way of visualising the equations to make them easier to understand and solve, and can be entirely done away with in favour of just solving the equations and deriving values for observable quantities - hey presto, no curved space-time and no need for a background.

So, applying this to 'multiverses', each different universe is also not anywhere, and the question of where they are in relation to each other becomes meaningless. Essentially, the concept of reality is practically restricted to inside one's own universe. Strangely, this seems to make meaningless the question of whether the universe itself is real, as it's not clear what you mean by real when talking about the universe.

There is one (very very speculative) counter-argument to all this that I've heard. That is that the reason quantum computing seems to violate 'normal' restrictions on calculation power is that it effectively performs some of its calculations in those other universes simultaneously with our own, implying a connection.

If this makes your head hurt, rest assured it makes mine hurt too.

[astroron (Ron)]

If this makes your head hurt, rest assured it makes mine hurt too.
(Quote)



It sure does Dave
I wonder if they could put the same amount of thought into solving some of the problems in our present Universe,which is hard enough to understand never mind some Hypothetical Multiverse's
Cheers

[Wavytone]

Originally Posted by snas

how do I get to exist in these other universes?

There are a few problems with your 'multiverse' hypothesis:

a) you might never have been born, or might have died
b) it is impossible to know anything about your doppelgängers...
c) even assuming they exist, the reality is you don't know about them.

So it makes no difference if they exist or not; you are firmly rooted in THIS universe.

Hypotheses are only useful if they make a prediction that can be tested.

This one can't, ergo it's therefore rubbish.

[DJDD]

if we could check out our other selves in other universes I would feel sorry for all of the Adrians that decided not to do it in all of the new universes that were created!

this all sounds like an episode of Red Dwarf! Remember "Ace" Rimmer?

[Dave2042 (Dave)]

Originally Posted by Wavytone

There are a few problems with your 'multiverse' hypothesis:

a) you might never have been born, or might have died
b) it is impossible to know anything about your doppelgängers...
c) even assuming they exist, the reality is you don't know about them.

So it makes no difference if they exist or not; you are firmly rooted in THIS universe.

Hypotheses are only useful if they make a prediction that can be tested.

This one can't, ergo it's therefore rubbish.

Hmmm. Yes and no, I think. I certainly agree with a, b and c, plus your point about being rooted in this universe.

As to hypotheses only being useful if testable, yes as far as it goes, however one needs to consider whether a hypothesis is just not testable yet. I think speculative science is a fair activity as long as it's recognised as such. As I mentioned last post, quantum computing does hold a faint hope of this being testable in some sense. Also, I recall some cosmologist (name long forgotten) producing a line of reasoning that suggested it was testable at least in principle (details also forgotten).

Finally, I'd characterise something as rubbish if it is demonstrably false, internally incoherent, wildly at odds with well understood science or grossly misrepresented as to its import. I can't see the multiverse as fitting this, unless someone tries to claim it is a done deal and not speculative.

Astroron - sadly agree with you. It's not the universe that's the problem but the contents of this corner of it.

[allan gould]

Epicycles!
It's all conjecture and doesn't click with me at all. No proof whatsoever but in another universe I've been proved right and all alternates collapse into one.

[Dave2042 (Dave)]

Here you go. The paper below looks at whether you might in principle distinguish between many-worlds and single-world versions of QM by observation.

I'm not saying I agree with the content, but make the points that (a) this is an example of a scientist trying to find a way of testing the multiverse hypothesis experimentally and (b) you'll see in the conclusion that the speculative nature of the work is appropriately acknowledged.

http://xxx.lanl.gov/pdf/gr-qc/0001001v1.pdf

[snas (Stuart)]

Thanks everyone for all the replies. I wasn't expecting to hop on a bus to the universe where there is always perfect surf at my favourite break, but dang! I wish I could.
Not that I believe in the concept of me existing in multiple different universes having slightly different lives in each, but when I thought about it I realised that if this was to happen, then all of those universes HAD to be absolutely identical. If not, then the odds of another ME being born in these other universes would be impossible.
Just a silly little thought experiment.

regards

Stuart