Thursday, August 1, 2013

The Bottomless Starbucks Gift Card and Quantum Immortality

I have recently acquired an item of rare wonder and power.  An artifact of legend, forged in a mythical age.  I am now the owner of the Bottomless Starbucks Gift Card.

From Piled Higher and Deeper
How this enchanted relic came in to my possession is common enough.  Believe it or not, it was given to my mother (a middle school teacher) as an end-of-semester present.  She, seeing no need to for it, did bequeath it unto me.  And I, a grad student in physics, have found very much need for some extra coffee money.

I've gone through a number of these re-gifted Starbucks cards from my mom, almost all of which were for $5.  They got me about two uses, then I'd switch to the next.  I seriously carried four or five of them around, gradually burning through them.  But the Bottomless Card... that's the last one I came to.

I have no idea how much money is on it, or was on it.  I go up to the counter, order whatever I want, show them the card, they swipe it, and there's always still enough money left for next time.

There is an interpretation of Quantum Mechanics that is called Everett's Many-Worlds Hypothesis.  This is often misunderstood and abused by science fiction authors, and philosophers as implying something stronger than it actually does -- the actual existence of parallel universes with alternative versions of ourselves (like in His Dark Materials).  This isn't quite what it means; it's more like every quantum measurement, rather than resulting in a collapse of the wave function, actually results in the further entanglement of the observer with one of the terms in the superposition.  The parts of the universal wave function describing us continue to exist but now in a superposition, one with every possibility of the measurement.  It's kind of the same thing, but not really.
From Asbtruse Goose

Everett's is a popular interpretation and appears frequently cited in "popular science" articles and books.  It is not the strict implication of quantum mechanics, nor is it anything more than a philosophical framework built around quantum mechanics, but it's there and cited a lot.  Most of the appeal is the fantasticality of it; alternative universes, Narnia, cool!  There's also some physicists who prefer it for philosophical reasons; for instance, Everett's hypothesis would recover a deterministic universe, which was believed to be broken by quantum measurement.  Actually, Frank Tipler -- physicist, transhumanist, many-worldsist, and all around weird dude --  proposed an experiment to test Everett's based on the convergence of quantum interference patterns, to see if "probability" were in fact "leaking" to another universe.  I have no idea why no one has done this experiment yet, but he's put it out there.

Tipler's experiment is slightly more sane than another proposal: Quantum Immortality.

Quantum Immortality is - roughly - proposed to work in the following way.  You have a quantum gun; whether it fires a bullet when you pull the trigger is tied to some quantum mechanical superposition, so there is always a chance it won't fire.  In the Everett interpretation, each time you do this, your wave function splits in to two "worlds": one where the gun fires, the other where it doesn't.  The experiment calls for you to point the gun at your head and pull the trigger.  In Everett's interpretation, each time you do this, your wave function splits in to "dead" and "alive" parts; therefore, even if you do this 10,000 times, there still exists some version of you in some "universe" that is still alive.  Therefore, if you pull the trigger 10,000 times and live, you can conclude that you live in the "world" where you're still alive.

Here's an illustration from Super Mario World, where Mario keeps splitting and one Mario copy always survives:


The Quantum Immortality experiment doesn't require that you point the gun at your head.  It basically just states that if you keep making a quantum observation and keep getting the same result, then it makes more sense to assume you live in a universe that is a segment of a multiverse than that you just keep getting lucky.  You could even do this experiment with...

... a Starbucks Gift Card.

I have no idea how much money is on the card.  Each time I swipe it, I make an observation of whether or not there is sufficient money for my purchase.  There always is.  Always.  It's been weeks, and I still have enough money.  I've even started ordering fancy-fru-fru drinks and it keeps working.  It always works.

So now you can see how it works.  So long as I don't directly observe the exact amount of money on the card, there is no exact amount of money on the card!  Between "No Money" and "Yes Money", I also happen to live in the universe where the Card always splits to the "Yes Money" side of things.  Always.

And that is how I came upon the key to eternal coffee, and the strange mysteries that went to forging its powers.

[P.S. I'm not going to bother explaining every thing wrong with the Quantum Immortality proposal, nor my wonky application of it to an inherently non-quantum event.  Suffice it to say, almost none of it is scientifically rigorous, and Everett's interpretation is pretty dumb, even if it makes for fun science fiction.]

1 comment:

  1. Thanks for posting this. How was the card been holding up? Very curious because these types of things happen to me without thinking about it...noticing it happening started me on a course that led me here. Curious to know after time what your thoughts are about this situation now. Thanks!!!

    ReplyDelete

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