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Identity Isn't In Specific Atoms

23 Post author: Eliezer_Yudkowsky 19 April 2008 04:55AM

Continuation ofNo Individual Particles
Followup toThe Generalized Anti-Zombie Principle

Suppose I take two atoms of helium-4 in a balloon, and swap their locations via teleportation.  I don't move them through the intervening space; I just click my fingers and cause them to swap places.  Afterward, the balloon looks just the same, but two of the helium atoms have exchanged positions.

Now, did that scenario seem to make sense?  Can you imagine it happening?

If you looked at that and said, "The operation of swapping two helium-4 atoms produces an identical configuration—not a similar configuration, an identical configuration, the same mathematical object—and particles have no individual identities per se—so what you just said is physical nonsense," then you're starting to get quantum mechanics.

If you furthermore had any thoughts about a particular "helium atom" being a factor in a subspace of an amplitude distribution that happens to factorize that way, so that it makes no sense to talk about swapping two identical multiplicative factors, when only the combined amplitude distribution is real, then you're seriously starting to get quantum mechanics.

If you thought about two similar billiard balls changing places inside a balloon, but nobody on the outside being able to notice a difference, then... oh, hell, I don't know, go back to the beginning of the series and try rereading the whole thing over the course of one day.  If that still doesn't work, read an actual book on quantum mechanics.  Feynman's QED is a great place to start—though not a good place to finish, and it's not written from a pure realist perspective.

But if you did "get" quantum physics, then, as promised, we have now come to the connection between the truth of quantum mechanics, the lies of human intuitions, and the Generalized Anti-Zombie Principle.

Stirling Westrup previously commented, on the GAZP post:

I found the previous articles on Zombies somewhat tedious... Still, now I'm glad I read through it all as I can see why you were so careful to lay down the foundations you did.

The question of what changes one can make to the brain while maintaining 'identity' has been been discussed many times on the Extropians list, and seldom with any sort of constructive results.

Today's article has already far exceeded the signal to noise ratio of any other discussion on the same topic that I've ever seen...

The Extropians email list that Westrup refers to, is the oldest online gathering place of transhumanists.  It is where I made my debut as a writer, and it is where the cofounders of the Singularity Institute met.  Though the list is not what it once was...

There are certain topics, on the Extropians list, that have been discussed over and over again, for years and years, without making any progress.  Just the same arguments and counterarguments, over and over again.

The worst of those infinite loops concerns the question of personal identity.  For example, if you build an exact physical replica of a human, using different atoms, but atoms of the same kind in the same places, is it the same person or just a copy? 

This question has flared up at least once a year, always with the same arguments and counterarguments, every year since I joined the Extropians mailing list in 1996.  And I expect the Personal Identity Wars started well before then.

I did try remarking, "Quantum mechanics says there isn't any such thing as a 'different particle of the same kind', so wherever your personal identity is, it sure isn't in particular atoms, because there isn't any such thing as a 'particular atom'."

It didn't work, of course.  I didn't really expect it to.  Without a long extended explanation, a remark like that doesn't actually mean anything.

The concept of reality as a sum of independent individual billiard balls, seems to be built into the human parietal cortex—the parietal cortex being the part of our brain that does spatial modeling: navigating rooms, grasping objects, throwing rocks.

Even very young children, infants, look longer at a scene that violates expectations—for example, a scene where a ball rolls behind a screen, and then two balls roll out.

People try to think of a person, an identity, an awareness, as though it's an awareness-ball located inside someone's skull.  Even nonsophisticated materialists tend to think that, since the consciousness ball is made up of lots of little billiard balls called "atoms", if you swap the atoms, why, you must have swapped the consciousness.

Now even without knowing any quantum physics—even in a purely classical universe—it is possible to refute this idea by applying the Generalized Anti-Zombie Principle.  There are many possible formulations of the GAZP, but one of the simpler ones says that, if alleged gigantic changes are occurring in your consciousness, you really ought to notice something happening, and be able to say so.

The equivalent of the Zombie World, for questions of identity/continuity, is the Soul Swap World.  The allegation is that the Soul Swap World is microphysically identical to our own; but every five minutes, each thread of consciousness jumps to a random new brain, without the brains changing in any third-party experimentally detectable way.  One second you're yourself, the next second you're Britney Spears.  And neither of you say that you've noticed anything happening—by hypothesis, since you're microphysically identical down to the motion of your lips.

(Let me know if the Soul Swap World has been previously invented in philosophy, and has a standard name—so far as I presently know, this is my own idea.)

We can proceed to demolish the Soul Swap World by an argument exactly analogous to the one that demolished the Zombie World:  Whatever-it-is which makes me feel that I have a consciousness that continues through time, that whatever-it-is was physically potent enough to make me type this sentence.  Should I try to make the phrase "consciousness continuing through time" refer to something that has nothing to do with the cause of my typing those selfsame words, I will have problems with the meaning of my arguments, not just their plausibility.

Whatever it is that makes me say, aloud, that I have a personal identity, a causally closed world physically identical to our own, has captured that source—if there is any source at all.

And we can proceed, again by an exactly analogous argument, to a Generalized Anti-Swapping Principle:  Flicking a disconnected light switch shouldn't switch your personal identity, even though the motion of the switch has an in-principle detectable gravitational effect on your brain, because the switch flick can't disturb the true cause of your talking about "the experience of subjective continuity".

So even in a classical universe, if you snap your fingers and swap an atom in the brain for a physically similar atom outside; and the brain is not disturbed, or not disturbed any more than the level of thermal noise; then whatever causes the experience of subjective continuity, should also not have been disturbed.  Even if you swap all the classical atoms in a brain at the same time, if the person doesn't notice anything happen, why, it probably didn't.

And of course there's the classic (and classical) argument, "Well, your body's turnover time for atoms is seven years on average."

But it's a moot argument.

We don't live in a classical universe.

We live in a quantum universe where the notion of "same hydrogen atom vs. different hydrogen atom" is physical nonsense.

We live in a universe where the whole notion of billiard balls bopping around is fundamentally wrong.

This can be a disorienting realization, if you formerly thought of yourself as an awareness ball that moves around.

Sorry.  Your parietal cortex is fooling you on this one.

But wait!  It gets even worse!

The brain doesn't exactly repeat itself; the state of your brain one second from now is not the state of your brain one second ago.  The neural connections don't all change every second, of course.  But there are enough changes every second that the brain's state is not cyclic, not over the course of a human lifetime.  With every fragment of memory you lay down—and every thought that pops in and out of short-term memory—and every glance of your eyes that changes the visual field of your visual cortex—you ensure that you never repeat yourself exactly.

Over the course of a single second—not seven years, but one second—the joint position of all the atoms in your brain, will change far enough away from what it was before, that there is no overlap with the previous joint amplitude distribution.  The brain doesn't repeat itself.  Over the course of one second, you will end up being comprised of a completely different, nonoverlapping volume of configuration space.

And the quantum configuration space is the most fundamental known reality, according to our best current theory, remember.  Even if quantum theory turns out not to be really truly fundamental, it has already finished superseding the hallucination of individual particles.  We're never going back to billiard balls, any more than we're going back to Newtonian mechanics or phlogiston theory.  The ratchet of science turns, but it doesn't turn backward.

And actually, the time for you to be comprised of a completely different volume of configuration space, is way less than a second.  That time is the product of all the individual changes in your brain put together.  It'll be less than a millisecond, less than a femtosecond, less than the time it takes light to cross a neutron diameter.  It works out to less than the Planck time, if that turns out to make physical sense.

And then there's the point to consider that the physically real amplitude distribution is over a configuration space of all the particles in the universe.  "You" are just a factored subspace of that distribution.

Yes, that's right, I'm calling you a factored subspace.

None of this should be taken as saying that you are somehow independent of the quantum physics comprising you.  If an anvil falls on your head, you will stop talking about consciousness.  This is experimentally testable.  Don't try it at home.

But the notion that you can equate your personal continuity, with the identity of any physically real constituent of your existence, is absolutely and utterly hopeless.

You are not "the same you, because you are made of the same atoms".  You have zero overlap with the fundamental constituents of yourself from even one nanosecond ago.  There is continuity of information, but not equality of parts.

The new factor over the subspace looks a whole lot like the old you, and not by coincidence:  The flow of time is lawful, there are causes and effects and preserved commonalities.  Look to the regularity of physics, if you seek a source of continuity.  Do not ask to be composed of the same objects, for this is hopeless.

Whatever makes you feel that your present is connected to your past, it has nothing to do with an identity of physically fundamental constituents over time.

Which you could deduce a priori, even in a classical universe, using the Generalized Anti-Zombie Principle.  The imaginary identity-tags that read "This is electron #234,567..." don't affect particle motions or anything else; they can be swapped without making a difference because they're epiphenomenal.  But since this final conclusion happens to be counterintuitive to a human parietal cortex, it helps to have the brute fact of quantum mechanics to crush all opposition.

Damn, have I waited a long time to be able to say that.

And no, this isn't the only point I have to make on how counterintuitive physics rules out intuitive conceptions of personal identity.  I've got even stranger points to make.  But those will take more physics first.

 

Part of The Quantum Physics Sequence

Next post: "Three Dialogues on Identity"

Previous post: "No Individual Particles"

Comments (66)

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Comment author: Wiseman 19 April 2008 05:53:01AM 1 point [-]

Isn't each particle or amplitude configuration unique because only it has its exact relationship to every other amplitude configuration in the universe? Doesn't that sufficiently make each amplitude configuration at a specific spatial-temporal locality different from every other one, in that the universe can "tell" one from the other?

Comment author: Eliezer_Yudkowsky 19 April 2008 07:02:41AM 2 points [-]

Wiseman, there's only one amplitude distribution. One. Not two. Not three. One, in all the physics we know.

Occasionally you can approximate interacting blobs of amplitude within that distribution, as the product of several almost-independent subspaces; but this is a mere convenience of computation, it is not the truth.

Comment author: Will_Pearson 19 April 2008 07:08:05AM 2 points [-]

"Suppose I take two atoms of helium-4 in a balloon, and swap their locations via teleportation." Even a billiard ball-ist might complain you haven't swapped their momentums. You might also have to swap the excitation levels of the electrons, protons and gluons, to get a situation that is the same as far as our physics understands.

Comment author: mitchell_porter2 19 April 2008 08:00:36AM 1 point [-]

Over already? I thought we'd hear about many worlds, measure theory, decoherence, and Julian Barbour before we came to the end.

If this is the end, then it's time to evaluate the picture we've been given. Basically, it's nonsense. This is not particularly Eliezer's fault. As a sketch of how quantum mechanics works, it is accurate, and since quantum mechanics is generally not held to be in need of explanation itself, to some degree it has the imprimatur of orthodoxy as a sketch of reality itself. But that just means it is officially sanctioned nonsense.

Let's consider some of what we've been told. Suppose a physical system starts in situation A, and ends in situation B. The probability of this happening can be found by summing the amplitudes for a number of "histories" which began with A and end with B. OK; but what do we think actually happened in between? If those amplitudes were probabilities, it would be reasonable to say that just one of those histories actually happened. Not so in quantum mechanics; in quantum mechanics, sometimes things never happen because all the ways that they can happen cancel each other out (the amplitudes sum to zero). That is nonsense, it is an obvious indication that we are conceptualizing things incorrectly.

In any case, Eliezer seems to be saying that between A and B, what happens is everything and nothing. We have amplitude flows in configuration space. Configurations themselves do not change, just the amplitudes associated with them. Well, in real life something definitely changed - A became B. The picture needs more detail, to expain what that involves. Eliezer clearly favors the many-worlds explanation, but I can't critique it unless he shows me the details. For now, we just have underspecified nonsense.

It also turns out that the point of this digression was to make an argument about personal identity and its continuity over time: whatever the reason is that I, now, am to be considered the same entity as I, five minutes ago, it can't have to do with persistence of my physical parts, because my physical parts don't "have identity". So, if I focus on the proton in a particular hydrogen atom in a particular nucleotide in a particular cell in my body, I don't have any grounds for thinking that the proton that's there now is the same proton that was there a millisecond ago; at least, it's not that proton to any greater degree than it is also any other proton in the universe.

This is clealy an odd view. There are at least two possible reactions to it. One is to say, well, it's odd, but it's what Authority tells me that Experiment is saying, so I'd better believe it. Or, one might want to look a little closer at the details, and see if the peculiar interpretation holds up. In this case, I think that proceeding to the perspective of field configurations might be called for. I'm not at all sure that this stuff about indistinguishability is anything more than an artefact of taking particle configurations to be fundamental, rather than field configurations. (And that, incidentally, is another aspect of the quantum problem that this exposition hasn't mentioned, the question of which "basis" to use.)

Just some preliminary thoughts.

Comment author: Eliezer_Yudkowsky 19 April 2008 08:06:47AM 2 points [-]

Over already? I thought we'd hear about many worlds, measure theory, decoherence, and Julian Barbour before we came to the end.

No, not over. Yes, the plan calls for Heisenberg, decoherence, many worlds, and Barbour.

Comment author: mitchell_porter2 19 April 2008 08:30:09AM 0 points [-]

I'll sit down and let the second act begin, then. :-)

Comment author: Tom_McCabe2 19 April 2008 02:51:35PM 1 point [-]

"If you furthermore had any thoughts about a particular "helium atom" being a factor in a subspace of an amplitude distribution that happens to factorize that way,"

If a helium atom is just an accidential, temporary factorization of an amplitude distribution, then why does it keep appearing over and over again when we look at the universe? If you throw a thousand electrons together, let them interact, zap them with laser radiation, etc., etc., at the end of the day you will still see a bunch of electrons with 511 keV rest mass and -1 charge. Why does the universe so carefully conserve these particular bundles of amplitude, with only one exception that I am aware of (annihilation by positrons), while other bundles of amplitude never exist at all (eg., a particle with 360 keV rest mass, or a particle with 7/2 charge).

Comment author: David_D 19 April 2008 03:25:06PM 3 points [-]

If that still doesn't work, read an actual book on quantum mechanics. Feynman's QED is a great place to start..

Since I was pretty much lost after the first few posts in this series, this is exactly what I am doing. I've gone through the first 2 chapters, and what has surprised me is that at least one part of it (explaining why light "bends" when it goes through a material with a different refractive index) has been MORE intuitive to me than the "classical" explanation. The explanation (or shall I say, analogy) I have always heard is that light is like a bunch of soldiers that "want" to stay in line, so when they hit a patch of mud (i.e. when they have to move slower) they change direction. Another explanation I have been given (which is a bit closer to the QED one) is that light "wants" to get from point A to point B as fast as possible, so it "chooses" the path through the glass (or whatever) that will accomplish this.

The QED explanation (i.e. all of the fastest paths tend to have similar phases so they do not cancel each other out like the slower ones do) was much more satisfying.

FWIW, learning about amplitudes in terms of complex numbers before I started reading the book really helped me grok the arrows that Feynman uses. Otherwise, it would probably take my brain a few steps to keep the "amplitude arrows" and the "possible path of the photon arrows" separate.

Anyway, if anybody reading these posts are as lost as me, I would strongly recommend the QED book.

Comment author: Wiseman 19 April 2008 03:26:42PM 0 points [-]

Wiseman, there's only one amplitude distribution. One. Not two. Not three. One, in all the physics we know.

I do understand this Eliezer. But my point is even though it's just one distribution, there is still a description of differentation within that one distribution, otherwise the universe would be just one electron, or something like that. So since there is differentation within the distribution, and since those differentations are tracked and consistent due to the non-random laws of this universe, isn't that really the same as "identity", in that the "differentations" are always 100% unique?

Comment author: Aaron_Boyden 19 April 2008 05:26:56PM 0 points [-]

I don't know a standard name for it, but the soul-swap issue is quite old. Locke is interpreted as making some similar point in chapter XXVII, section 13 of the _Essay Concerning Human Understanding_; I know I always hear the point attributed to Locke, so he may be the first.

Comment author: Unknown 19 April 2008 06:52:23PM -2 points [-]

Eliezer has the same problem here as with the zombie argument. The point isn't that there are zombie worlds, or soul swap worlds. Saying that something is logically possible is nowhere near saying that something is actual. It is logically possible for someone to be kidnapped, have his brain placed in a vat, and information fed in producing the impression that his experiences are in precise continuity with his experiences the day before being kidnapped. Of course, he will have no way to notice this. In fact, it is logically possible that that this just happened to you, the reader, in the middle of this sentence, with your vat experiences beginning with the words "the reader."

The fact that there is absolutely no way to prove or disprove this scenario does not make it logically impossible. It just makes it highly improbable. Likewise, the soul swap world, and the zombie world, are highly improbable. This is no reason at all to call them logically impossible.

This whole thing is simply another case of Eliezer's overconfidence: if there is something that one should be somewhat confident of, then he is extremely confident of it. If there is something that one should be extremely confident about, such as that there are no zombies in the world, then he is infinitely certain about it: he thinks it is logically impossible.

Comment author: Richard4 19 April 2008 08:23:47PM 0 points [-]

I actually agree with the reductionist view about personal identity, though of course for very different reasons from Eliezer. (I think that identity-swapping is strictly inconceivable. There is no difference there in what the world is like, in stark contrast to the zombie or BIV case where we can understand the (albeit undetectable) difference in how things are.)

Comment author: Caledonian2 19 April 2008 08:47:50PM 2 points [-]

Likewise, the soul swap world, and the zombie world, are highly improbable. This is no reason at all to call them logically impossible.

That isn't why he's calling them logically impossible. It's the self-contradictions inherent in their definitions that causes him to reject those ideas.

Eliezer makes many errors. That is not one of them.

Comment author: Toby_Ord2 19 April 2008 09:04:44PM 0 points [-]

>> Suppose I take two atoms of helium-4 in a balloon, and swap their locations via teleportation.

For a book version, you will definitely want to be more precise here. I assumed they were in different quantum states (this seems a very reasonable assumption failing a specification to the contrary). Perhaps they had different spins, energies, momenta, etc. This means that the swapping *did* make sense.

Comment author: Z._M._Davis 19 April 2008 11:56:35PM 0 points [-]

Anonymous, you don't seem to understand the reductionist thesis: the claim is that there isn't any consciousness-stuff; it only seems like it because we're stupid—which is also a remarkable claim, in its own way, but it beats the alternatives.

Unknown: "[...] then he is infinitely certain about it [...]"

Really?—cf. "Infinite Certainty" and "0 and 1 Are Not [...]"

Thinking that something is logically impossible doesn't imply infinite certainty if we permit impossible possible worlds.

Comment author: Hopefully_Anonymous 20 April 2008 01:44:10AM 0 points [-]

"Anonymous, you don't seem to understand the reductionist thesis: the claim is that there isn't any consciousness-stuff; it only seems like it because we're stupid—which is also a remarkable claim, in its own way, but it beats the alternatives."

It beats the alternative that "we don't know enough to make a claim right now"? For example, I think that's the leading claim about what preceded or sparked the big bang, beating out other 'remarkable' claims like that we're in an infinite cycle of big bangs, that our big bang resulted from a black hole forming in another universe, etc.

Here I'm defining 'consciousness-stuff' in what I think is the most reasonable and useful way for this discussion, that there may be something to subjective consciousness more than whatever can currently fool the best human observers in 2008 into thinking it's subjectively conscious. This is probably a higher bar than 40th percentile ability level human observers of 2008 BCE, but perhaps a significantly lower bar than the best human observers of 2038. If the best human observers of 2038 have singificantly improved knowledge and technology, they might be able to make more nuanced discernments between what is or is not likely subjective conscious than the best humans can in 2008. If so, in all practical respects, I think that those differences they'll be able to discern can be called "cosciousness-stuff" of which we're current unaware. Here I'm not specifically referring to a tagged electron, or a tagged factored subspace, but rather, when Eliezer writes:

"None of this should be taken as saying that you are somehow independent of the quantum physics comprising you. If an anvil falls on your head, you will stop talking about consciousness. This is experimentally testable. Don't try it at home."

I'm referring to consciousness-stuff as the minimal distinguishable elements of reality required for the maintainence of the subjective conscious experience which Eliezer implies in the above quote could be ended "if an anvil falls on your head".

In my opinion, this is a more interesting place to bring the discussion, than to look for easy dragons to slay such as (scare quotes) "These people think individual electrons are discrete entities. I can show that the best science disproves that and thus end any concern that post-cryonic reanimation or post-uploading I won't have an experience of being 'alive' or 'conscious'.

Comment author: Bob5 21 April 2008 08:06:58PM 0 points [-]

This has been a fascinating series of posts. You are suggesting a realistic interpretation of QM. Do you take the real universe to be the (single) point in the universal QM configuration space, along with the single complex value of the universal wavefunction? Or, since the wavefunction is a function of all possible configurations, are those other configurations somehow real as well (which would be some sort of multiverse theory)? Quantum mechanics certainly allows wavefunctions comprising superpositions of different configurations. Are these superposition states not fundamental?

Comment author: xrchz 31 October 2009 09:52:34PM *  0 points [-]

Do you take the real universe to be the (single) point in the universal QM configuration space, along with the single complex value of the universal wavefunction?

No, the universe is an (evolving) amplitude distribution over configuration space.

I'm not what "superposition state" means, but my guess is that the answer to "Are these superposition states not fundamental?" is "Yes they are".

Comment author: Nick_Tarleton 21 April 2008 08:25:02PM 0 points [-]

And I expect the Personal Identity Wars started well before then.

No later than 1987.

Comment author: Richard4 22 April 2008 12:08:54AM -2 points [-]

I've a new post - 'Non-causal Talk' - which points out some problems with Eliezer's assumption that our words refer to whatever causes us to utter them.

Comment author: Caledonian2 22 April 2008 12:43:35AM 3 points [-]

No, Richard. Just... no.

How can you have missed the point that badly?

Comment author: lucidfox 14 December 2010 10:36:53AM 2 points [-]

The equivalent of the Zombie World, for questions of identity/continuity, is the Soul Swap World. The allegation is that the Soul Swap World is microphysically identical to our own; but every five minutes, each thread of consciousness jumps to a random new brain, without the brains changing in any third-party experimentally detectable way. One second you're yourself, the next second you're Britney Spears.

This scenario strikes me as logically incoherent - for much the same reason as I don't buy "body swap" scenarios in science fiction.

There is no such thing as a "me" that can jump between brains. If "jumping between brains" means something, then it could mean two things:

  1. For me to subjectively experience "waking up as Britney Spears", I'll need to retain the memories of being the current me up to that point. That would mean that Britney Spears' brain would need to be physically altered to inscribe my memories, rather than hers, which contradicts our premise that no physical attributes are being altered.

  2. If "I" end up in Britney Spears' body but lose "my" original memories, and likewise "Britney Spears" becomes me, then it no longer makes any sense to speak about preservation of personal identity, any more than it makes sense to ask "If we simultaneously yanked every plank composing the Ship of Theseus out of its space, and warped different planks into their space to make a ship of a completely different shape, would it still be the same ship"? If "being the same ship" or "being the same person" means anything at all, then it is a different ship, and likewise, the hypothetical "me in Britney Spears' body but with Britney Spears' memories instead of mine" is exactly the same person as Britney Spears. There is no incorporeal identity tag that we can attach to minds, any more than we can do so for electrons.

Comment author: shokwave 14 December 2010 10:47:43AM 3 points [-]

If "I" end up in Britney Spears' body but lose "my" original memories, and likewise "Britney Spears" becomes me, then it no longer makes any sense to speak about preservation of personal identity

That is the intended conclusion from the Soul Swap World thought-experiment.

Comment author: k3nt 19 October 2011 05:54:23AM 7 points [-]

Well I've finally gotten to this point in the series and I have to say how strange it is to have worked through a ton of very hairy quantum physics (which I still don't fully understand, not really, not by a long shot) ... only to have it utilized to bring down a hammer on a thoroughly stupid philosophical argument. Feels a little like using a car crusher to pop a balloon. But the ride has been enjoyable. Thanks.

Comment author: khafra 19 October 2011 01:27:40PM 5 points [-]

The way I look at this sequence is, after building the car crusher and using it to pop the balloon, you still own a brand new car crusher. That's pretty cool.

Comment author: QuicklyStarfish 03 April 2012 07:48:55PM 0 points [-]

Before when I was still contemplating whether consciousness had a non-physical component, well before I discovered coherent philosophy or rationalism, I had a similar "soul swap world" idea. It eventually let me discard the idea of a soul, but I still favoured some kind of non-personal consciousness. This idea eventually became that there was a "consciousness field" permeating space which produced the phenomenon, through interaction with our brains through a physical yet unknown mechanism. I thought it some very subtle physical effect we hadn't noticed yet, not really supernatural.

It was progress.