Sunday, November 18, 2007

Expecting Immortality

"The experience of being dead should never be expected to any degree at all, because there is no such experience." So writes David Lewis in 'How Many Lives Has Schrodinger's Cat?' (p.17) But perhaps we can have negative expectations, in the sense of not positively expecting any further experiences.

What if I split, amoeba-style, into two future persons, one of whom is promptly shot? In general, I should split my expectations evenly between my future branches. Perhaps I should anticipate the experiences of each branch, separately. (I do not, of course, experience both lives together, in any mutually-accessible kind of way.) If one branch has no experiences at all - being killed before ever awakening, say - then all there is to anticipate is the other, surviving branch. But if it gets to experience a little before dying, then it would seem one allotment of my expectations should capture precisely this: to experience seeing the bullet approaching (or whatever), and then no more.

This is important because if the "no collapse" (or many-worlds) interpretation of Quantum Mechanics is correct, then we are actually splitting all the time. If you shoot me, there exists some (extremely low intensity) state in the superposition in which the bullet passes right through me. However often I die, there is always some version of me that survives. Should I expect, then, to be immortal? Lewis thinks so (p.19):
Suppose you're fairly sure that there are no collapses, and you're willing to run a risk in the service of truth. Go and wander about on a busy road, preferably a few minutes after closing time. When and if you find yourself still alive, you will have excellent evidence [for the no-collapse view]. If that's not yet enough to convince you, try the experiment a few more times.

What should you expect to happen?
(1) You miraculously emerge unscathed (perhaps the cars pass right through you by some quantum fluke).
(2) You get hit by a car, and then have no further experiences (due to being dead).
(3) You get hit by a car, but then miraculously survive (perhaps your crushed body reassembles itself by some quantum fluke).

On the no collapse view, all these outcomes occur, but (presumably) the second does so with much higher frequency or "intensity". Still, even if the overwhelmingly majority of superimposed states involve your getting hit by a car, you will always have some branch that survives this. So there are always further experiences to anticipate. Does this mean we should never anticipate ending up on a dead branch, i.e. one that has no further experiences?

It's not quite enough to ask whether we should expect to be immortal. On the no-collapse view, we are undoubtedly immortal, in the sense that we will always have some surviving branch. But we also die a lot, in that we have a great many terminating branches! So the real question is whether we should ever expect to die. Can our expectations be distributed over branches that contain no further experiences? Or are they restricted to the survivors only?


  1. There was a good article by Papineau on this paper by Lewis, in the Australasian Journal of Philosophy 82 (2004) 153-69.

  2. Interesting take on multi-verse consequences.

  3. Yes, v. interesting; of course we do expect to die, and presumably we ought to as well. You'd tell a child that if they behaved as Lewis suggests then s/he should expect to die. It seems that we could expect, with various degrees of probability (given by quantum mechanics and our notion of identity), to die in various scenarios.

    But those measures of likely outcomes seem distinct from our measures of identity. E.g. I'm pretty sure that I'm wholly me at the moment. Infinitely many of who I was are now living different lives (according to no-collapse theories), but I'm not any the less for that, even though this me, in all its particularity, was rather unlikely.

    So too, infinitely many of me would survive my trip into the busy road, and infinitely many would die; and any survivor would have been an unlikely outcome, as would any of the particular dead. But we surely can't reason as though being this particular me is just like having survived the busy road. So no-collaspe theories hardly capture probabilities.

  4. haha almost my theory! (which I half explained a while ago on here)
    Anyway here are some thoughts

    1) If you are a cloud of probabilities* (a Schrodinger's Cat) it is not a case of branching - a certain percentage of you 'dies' at any particular instant not a certain number of you. In fact you could say a certain percentage die at EVERY instant. (how does it feel?)

    2) What do you mean by 'die'? you could expect that certain future scenarios might not include you, but they also, presumably, don't have any you to fail to experience anything (i.e. no 'limbo').
    rather like walking down a corrador and a series of (potential) you 'dying' (i.e. there being no world created that has you on the other side of those doors) because you don't choose to take some of those doors.

    3) In a sense you never get to die i.e. not even one of the infinite yous gets to experiences death.
    and your average experience (however you define 'you') - contains no 'death' component.

    4) In the theory that I have previously explained to you it doesn't directly matter if your branch terminates as long as there is somthing for you to "jump to" anyway. thats a mater of how one defines personal identity but I think it is the most robust definition.

    I think it would be interesting to convet someone to a believer by disconecting 'them' from their other forms of identity.

    5) collapse presumably still leaves the branching option open - it also raises the question of whether a soul 'experiences' collapse, or whether it just notices colapse in other systems - while never collapsing from it's own perspective.


    anyway a thought experiment for you

    A) Imagine an experiment where someone turns off one side of your brain and all the information happens to be duplicated on the other side. What do you expect to experience? Some people have probably - more or less - done this test already.

    * I note however, that I think it would be possible that you might wipe out your entire cloud in certain situations.


  5. I note David Lewis seems to have also discovered the down side that I noticed - that is that any death (I don't think there is an exception) will experience a period of "fading out"/maiming where the stage instantly before death is probably if not unplesant at least rather unfufilling.
    I can counter that with my theory of continuality (wherein you would tend to dodge psychological maiming) but even that is vulnerable to some sort of latent tendancy to gradually fade/be damaged - since that could be part of what defines you (rahter like how entropy, in part, defines you) the strategic choice would then be to do whatever you could to eliminate even slightly more sickly versions of yourself.


    Anyway Ill take on the colapse non collapse isue...

    Now lests imagine the universe as in infinite set of Schrodinger's Cat boxes all the size of a photon where nothing is collapsed but it will collapse on connection to somthing else. Now lets imagine them all slowly growing to the size of a cat in a box.

    That that could happen only seems to make sense if it is a relitive collapse, ie the cat collapses relitive to the set it interacts with and only that set. That would be a standard sort of interpretation.

    But that means that the universe can't be fully collapsed from the point of view of an external object (or lets say a multiverse traveler (as long as everything is of the same nature) because we are effectively one huge box with a cat in side no matter how many little boxes we are made from.

    So that means that in as far as we think we are real then we should also think the alive and dead Schrodinger's Cat is real (because we are both in a sense uncollapsed wave functions). - so what happens to the Schrodinger's Cat that is alive if we open it and find him dead? And what hapens to us if the cat opens the box and sees us alive or dead?

    The solution edges towards there being a certain realness to the options of hte sort that would support quantum imortality.



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