Where Physics Meets Experience
post by Eliezer Yudkowsky (Eliezer_Yudkowsky) · 2008-04-25T04:58:11.000Z · LW · GW · Legacy · 38 commentsContents
38 comments
Followup to: Decoherence, Where Philosophy Meets Science
Once upon a time, there was an alien species, whose planet hovered in the void of a universe with laws almost like our own. They would have been alien to us, but of course they did not think of themselves as alien. They communicated via rapid flashes of light, rather than sound. We'll call them the Ebborians.
Ebborians reproduce by fission, an adult dividing into two new individuals. They share genetic material, but not through sexual recombination; Ebborian adults swap genetic material with each other. They have two eyes, four legs, and two hands, letting a fissioned Ebborian survive long enough to regrow.
Human DNA is built in a double helix; unzipping the helix a little at a time produces two stretches of single strands of DNA. Each single strand attracts complementary bases, producing a new double strand. At the end of the operation, a DNA double helix has turned into two double helices. Hence earthly life.
Ebborians fission their brains, as well as their bodies, by a process something like how human DNA divides.
Imagine an Ebborian brain as a flat sheet of paper, computing in a way that is more electrical than chemical—charges flowing down conductive pathways.
When it's time for an Ebborian to fission, the brain-paper splits down its thickness into two sheets of paper. Each new sheet is capable of conducting electricity on its own. Indeed, the Ebborian(s) stays conscious throughout the whole fissioning process. Over time, the brain-paper grows thick enough to fission again.
Electricity flows through Ebborian brains faster than human neurons fire. But the Ebborian brain is constrained by its two-dimensionality. An Ebborian brain-paper must split down its thickness while retaining the integrity of its program. Ebborian evolution took the cheap way out: the brain-paper computes in a purely two-dimensional way. The Ebborians have much faster neuron-equivalents, but they are far less interconnected.
On the whole, Ebborians think faster than humans and remember less. They are less susceptible to habit; they recompute what we would cache. They would be incredulous at the idea that a human neuron might be connected to a thousand neighbors, and equally incredulous at the idea that our axons and dendrites propagate signals at only a few meters per second.
The Ebborians have no concept of parents, children, or sexuality. Every adult Ebborian remembers fissioning many times. But Ebborian memories quickly fade if not used; no one knows the last common ancestor of those now alive.
In principle, an Ebborian personality can be immortal. Yet an Ebborian remembers less life than a seventy-year-old human. They retain only the most important highlights of their last few millennia. Is this immortality? Is it death?
The Ebborians had to rediscover natural selection from scratch, because no one retained their memories of being a fish.
But I digress from my tale.
Today, the Ebborians have gathered to celebrate a day which all present will remember for hundreds of years. They have discovered (they believe) the Ultimate Grand Unified Theory of Everything for their universe. The theory which seems, at last, to explain every known fundamental physical phenomenon—to predict what every instrument will measure, in every experiment whose initial conditions are exactly known, and which can be calculated on available computers.
"But wait!" cries an Ebborian. (We'll call this one Po'mi.) "But wait!", cries Po'mi, "There are still questions the Unified Theory can't answer! During the fission process, when exactly does one Ebborian consciousness become two separate people?"
The gathered Ebborians look at each other. Finally, there speaks the moderator of the gathering, the second-foremost Ebborian on the planet: the much-respected Nharglane of Ebbore, who achieved his position through consistent gentleness and courtesy.
"Well," Nharglane says, "I admit I can't answer that one—but is it really a question of fundamental physics?"
"I wouldn't even call that a 'question'," snorts De'da the Ebborian, "seeing as how there's no experimental test whose result depends on the answer."
"On the contrary," retorts Po'mi, "all our experimental results ultimately come down to our experiences. If a theory of physics can't predict what we'll experience, what good is it?"
De'da shrugs. "One person, two people—how does that make a difference even to experience? How do you tell even internally whether you're one person or two people? Of course, if you look over and see your other self, you know you're finished dividing—but by that time your brain has long since finished splitting."
"Clearly," says Po'mi, "at any given point, whatever is having an experience is one person. So it is never necessary to tell whether you are one person or two people. You are always one person. But at any given time during the split, does there exist another, different consciousness as yet, with its own awareness?"
De'da performs an elaborate quiver, the Ebborian equivalent of waving one's hands. "When the brain splits, it splits fast enough that there isn't much time where the question would be ambiguous. One instant, all the electrical charges are moving as a whole. The next instant, they move separately."
"That's not true," says Po'mi. "You can't sweep the problem under the rug that easily. There is a quite appreciable time—many picoseconds—when the two halves of the brain are within distance for the moving electrical charges in each half to tug on the other. Not quite causally separated, and not quite the same computation either. Certainly there is a time when there is definitely one person, and a time when there is definitely two people. But at which exact point in between are there two distinct conscious experiences?"
"My challenge stands," says De'da. "How does it make a difference, even a difference of first-person experience, as to when you say the split occurs? There's no third-party experiment you can perform to tell you the answer. And no difference of first-person experience, either. Your belief that consciousness must 'split' at some particular point, stems from trying to model consciousness as a big rock of awareness that can only be in one place at a time. There's no third-party experiment, and no first-person experience, that can tell you when you've split; the question is meaningless."
"If experience is meaningless," retorts Po'mi, "then so are all our scientific theories, which are merely intended to explain our experiences."
"If I may," says another Ebborian, named Yu'el, "I think I can refine my honorable colleague Po'mi's dilemma. Suppose that you anesthetized one of us -"
(Ebborians use an anesthetic that effectively shuts off electrical power to the brain—no processing or learning occurs while an Ebborian is anesthetized.)
"- and then flipped a coin. If the coin comes up heads, you split the subject while they are unconscious. If the coin comes up tails, you leave the subject as is. When the subject goes to sleep, should they anticipate a 2/3 probability of seeing the coin come up heads, or anticipate a 1/2 probability of seeing the coin come up heads? If you answer 2/3, then there is a difference of anticipation that could be made to depend on exactly when you split."
"Clearly, then," says De'da, "the answer is 1/2, since answering 2/3 gets us into paradoxical and ill-defined issues."
Yu'el looks thoughtful. "What if we split you into 512 parts while you were anesthetized? Would you still answer a probability of 1/2 for seeing the coin come up heads?"
De'da shrugs. "Certainly. When I went to sleep, I would figure on a 1/2 probability that I wouldn't get split at all."
"Hmm..." Yu'el says. "All right, suppose that we are definitely going to split you into 16 parts. 3 of you will wake up in a red room, 13 of you will wake up in a green room. Do you anticipate a 13/16 probability of waking up in a green room?"
"I anticipate waking up in a green room with near-1 probability," replies De'da, "and I anticipate waking up in a red room with near-1 probability. My future selves will experience both outcomes."
"But I'm asking about your personal anticipation," Yu'el persists. "When you fall asleep, how much do you anticipate seeing a green room? You can't see both room colors at once—that's not an experience anyone will have—so which color do you personally anticipate more?"
De'da shakes his head. "I can see where this is going; you plan to ask what I anticipate in cases where I may or may not be split. But I must deny that your question has an objective answer, precisely because of where it leads. Now, I do say to you, that I care about my future selves. If you ask me whether I would like each of my green-room selves, or each of my red-room selves, to receive ten dollars, I will of course choose the green-roomers—but I don't care to follow this notion of 'personal anticipation' where you are taking it."
"While you are anesthetized," says Yu'el, "I will flip a coin; if the coin comes up heads, I will put 3 of you into red rooms and 13 of you into green rooms. If the coin comes up tails, I will reverse the proportion. If you wake up in a green room, what is your posterior probability that the coin came up heads?"
De'da pauses. "Well..." he says slowly, "Clearly, some of me will be wrong, no matter which reasoning method I use—but if you offer me a bet, I can minimize the number of me who bet poorly, by using the general policy, of each self betting as if the posterior probability of their color dominating is 13/16. And if you try to make that judgment depend on the details of the splitting process, then it just depends on how whoever offers the bet counts Ebborians."
Yu'el nods. "I can see what you are saying, De'da. But I just can't make myself believe it, at least not yet. If there were to be 3 of me waking up in red rooms, and a billion of me waking up in green rooms, I would quite strongly anticipate seeing a green room when I woke up. Just the same way that I anticipate not winning the lottery. And if the proportions of three red to a billion green, followed from a coin coming up heads; but the reverse proportion, of a billion red to three green, followed from tails; and I woke up and saw a red room; why, then, I would be nearly certain—on a quite personal level—that the coin had come up tails."
"That stance exposes you to quite a bit of trouble," notes De'da.
Yu'el nods. "I can even see some of the troubles myself. Suppose you split brains only a short distance apart from each other, so that they could, in principle, be fused back together again? What if there was an Ebborian with a brain thick enough to be split into a million parts, and the parts could then re-unite? Even if it's not biologically possible, we could do it with a computer-based mind, someday. Now, suppose you split me into 500,000 brains who woke up in green rooms, and 3 much thicker brains who woke up in red rooms. I would surely anticipate seeing the green room. But most of me who see the green room will see nearly the same thing—different in tiny details, perhaps, enough to differentiate our experience, but such details are soon forgotten. So now suppose that my 500,000 green selves are reunited into one Ebborian, and my 3 red selves are reunited into one Ebborian. Have I just sent nearly all of my "subjective probability" into the green future self, even though it is now only one of two? With only a little more work, you can see how a temporary expenditure of computing power, or a nicely refined brain-splitter and a dose of anesthesia, would let you have a high subjective probability of winning any lottery. At least any lottery that involved splitting you into pieces."
De'da furrows his eyes. "So have you not just proved your own theory to be nonsense?"
"I'm not sure," says Yu'el. "At this point, I'm not even sure the conclusion is wrong."
"I didn't suggest your conclusion was wrong," says De'da, "I suggested it was nonsense. There's a difference."
"Perhaps," says Yu'el. "Perhaps it will indeed turn out to be nonsense, when I know better. But if so, I don't quite know better yet. I can't quite see how to eliminate the notion of subjective anticipation from my view of the universe. I would need something to replace it, something to re-fill the role that anticipation currently plays in my worldview."
De'da shrugs. "Why not just eliminate 'subjective anticipation' outright?"
"For one thing," says Yu'el, "I would then have no way to express my surprise at the orderliness of the universe. Suppose you claimed that the universe was actually made up entirely of random experiences, brains temporarily coalescing from dust and experiencing all possible sensory data. Then if I don't count individuals, or weigh their existence somehow, that chaotic hypothesis would predict my existence as strongly as does science. The realization of all possible chaotic experiences would predict my own experience with probability 1. I need to keep my surprise at having this particular orderly experience, to justify my anticipation of seeing an orderly future. If I throw away the notion of subjective anticipation, then how do I differentiate the chaotic universe from the orderly one? Presumably there are Yu'els, somewhere in time and space (for the universe is spatially infinite) who are about to have a really chaotic experience. I need some way of saying that these Yu'els are rare, or weigh little—some way of mostly anticipating that I won't sprout wings and fly away. I'm not saying that my current way of doing this is good bookkeeping, or even coherent bookkeeping; but I can't just delete the bookkeeping without a more solid understanding to put in its place. I need some way to say that there are versions of me who see one thing, and versions of me who see something else, but there's some kind of different weight on them. Right now, what I try to do is count copies—but I don't know exactly what constitutes a copy."
Po'mi clears his throat, and speaks again. "So, Yu'el, you agree with me that there exists a definite and factual question as to exactly when there are two conscious experiences, instead of one."
"That, I do not concede," says Yu'el. "All that I have said may only be a recital of my own confusion. You are too quick to fix the language of your beliefs, when there are words in it that, by your own admission, you do not understand. No matter how fundamental your experience feels to you, it is not safe to trust that feeling, until experience is no longer something you are confused about. There is a black box here, a mystery. Anything could be inside that box—any sort of surprise—a shock that shatters everything you currently believe about consciousness. Including upsetting your belief that experience is fundamental. In fact, that strikes me as a surprise you should anticipate—though it will still come as a shock."
"But then," says Po'mi, "do you at least agree that if our physics does not specify which experiences are experienced, or how many of them, or how much they 'weigh', then our physics must be incomplete?"
"No," says Yu'el, "I don't concede that either. Because consider that, even if a physics is known—even if we construct a universe with very simple physics, much simpler than our own Unified Theory—I can still present the same split-brain dilemmas, and they will still seem just as puzzling. This suggests that the source of the confusion is not in our theories of fundamental physics. It is on a higher level of organization. We can't compute exactly how proteins will fold up; but this is not a deficit in our theory of atomic dynamics, it is a deficit of computing power. We don't know what makes sharkras bloom only in spring; but this is not a deficit in our Unified Theory, it is a deficit in our biology—we don't possess the technology to take the sharkras apart on a molecular level to find out how they work. What you are pointing out is a gap in our science of consciousness, which would present us with just the same puzzles even if we knew all the fundamental physics. I see no work here for physicists, at all."
Po'mi smiles faintly at this, and is about to reply, when a listening Ebborian shouts, "What, have you begun to believe in zombies? That when you specify all the physical facts about a universe, there are facts about consciousness left over?"
"No!" says Yu'el. "Of course not! You can know the fundamental physics of a universe, hold all the fundamental equations in your mind, and still not have all the physical facts. You may not know why sharkras bloom in the summer. But if you could actually hold the entire fundamental physical state of the sharkra in your mind, and understand all its levels of organization, then you would necessarily know why it blooms—there would be no fact left over, from outside physics. When I say, 'Imagine running the split-brain experiment in a universe with simple known physics,' you are not concretely imagining that universe, in every detail. You are not actually specifying the entire physical makeup of an Ebborian in your imagination. You are only imagining that you know it. But if you actually knew how to build an entire conscious being from scratch, out of paperclips and rubberbands, you would have a great deal of knowledge that you do not presently have. This is important information that you are missing! Imagining that you have it, does not give you the insights that would follow from really knowing the full physical state of a conscious being."
"So," Yu'el continues, "We can imagine ourselves knowing the fundamental physics, and imagine an Ebborian brain splitting, and find that we don't know exactly when the consciousness has split. Because we are not concretely imagining a complete and detailed description of a conscious being, with full comprehension of the implicit higher levels of organization. There are knowledge gaps here, but they are not gaps of physics. They are gaps in our understanding of consciousness. I see no reason to think that fundamental physics has anything to do with such questions."
"Well then," Po'mi says, "I have a puzzle I should like you to explain, Yu'el. As you know, it was discovered not many years ago, that our universe has four spatial dimensions, rather than three dimensions, as it first appears."
"Aye," says Nharglane of Ebbore, "this was a key part in our working-out of the Unified Theory. Our models would be utterly at a loss to account for observed experimental results, if we could not model the fourth dimension, and differentiate the fourth-dimensional density of materials."
"And we also discovered," continues Po'mi, "that our very planet of Ebbore, including all the people on it, has a four-dimensional thickness, and is constantly fissioning along that thickness, just as our brains do. Only the fissioned sides of our planet do not remain in contact, as our new selves do; the sides separate into the fourth-dimensional void."
Nharglane nods. "Yes, it was rather a surprise to realize that the whole world is duplicated over and over. I shall remember that realization for a long time indeed. It is a good thing we Ebborians had our experience with self-fissioning, to prepare us for the shock. Otherwise we might have been driven mad, and embraced absurd physical theories."
"Well," says Po'mi, "when the world splits down its four-dimensional thickness, it does not always split exactly evenly. Indeed, it is not uncommon to see nine-tenths of the four-dimensional thickness in one side."
"Really?" says Yu'el. "My knowledge of physics is not so great as yours, but—"
"The statement is correct," says the respected Nharglane of Ebbore.
"Now," says Po'mi, "if fundamental physics has nothing to do with consciousness, can you tell me why the subjective probability of finding ourselves in a side of the split world, should be exactly proportional to the square of the thickness of that side?"
There is a great terrible silence.
"WHAT?" says Yu'el.
"WHAT?" says De'da.
"WHAT?" says Nharglane.
"WHAT?" says the entire audience of Ebborians.
To be continued...
Part of The Quantum Physics Sequence
Next post: "Where Experience Confuses Physicists"
Previous post: "Which Basis Is More Fundamental?"
38 comments
Comments sorted by oldest first, as this post is from before comment nesting was available (around 2009-02-27).
comment by anonymous4 · 2008-04-25T05:47:00.000Z · LW(p) · GW(p)
This post just confirms that you should take your blooking efforts and turn them into money AND reach a much wider and more lasting audience by writing a book. I think you could do a book like GEB ... a long, quirky, multidisciplinary intro to cognitive biases, Bayes' theorem, Physics, the Singularity, and whatever else you might like, and people will buy it if you write like this.
comment by Eliezer Yudkowsky (Eliezer_Yudkowsky) · 2008-04-25T06:18:34.000Z · LW(p) · GW(p)
Thanks for the vote of confidence, anonymous; I hope you're right.
By the way, before anyone asks, this post is not intended to suggest that quantum physics takes place in the fourth dimension - I just wanted to present the Ebborians with a different but analogous bizarre puzzle.
comment by Will_Pearson · 2008-04-25T06:57:23.000Z · LW(p) · GW(p)
How do Ebborians get different names when they fission?
comment by Hopefully_Anonymous · 2008-04-25T08:19:25.000Z · LW(p) · GW(p)
Great writing. It's not hard to see where you took a lot of the debates about your writings and lifted them up into something greater -dare I say, art?
The great thing about novels and plays (this could be either) is it allows the writer to capture and express multiple points of view, without themselves committing to any of them.
I think this post is superior to your past ones in that it reflects a deeper understanding of various viewpoints on this topic, and expresses the best versions of them, rather than caricature views different than a particular one you promote in the post.
So I think you're moving from passion plays towards Shakespeare.
Like I said, great writing!
comment by GNZ2 · 2008-04-25T09:08:23.000Z · LW(p) · GW(p)
You could write a fiction short story series (like this but refined for print) with a summary at the end of what your trying to explain. I think it would be worth buying and it could combine entertaining with educational.
this story (and maybe others) could be a bit like the 10,000 year old man movie.
comment by Robin_Brandt · 2008-04-25T09:39:36.000Z · LW(p) · GW(p)
Agree, with anonymous, just can´t wait to read the whole book and deepen my understanding. With the right editing it will certainly be a new and even more important, insightful and rich book in the tradition of GEB! And I can´t wait to give it to all my friends and professors, and I can´t wait to hear the reception from academia, they/we have so much to learn. You will be on TED and on EDGE in no time! Your hard work, and deep thought is so precious, I think it is rather wonderful that a social ape can penetrate so deep into reality. I just think this blogform is a bit strange choice for such high quality material, a wiki would be much more appropriate and easy to use. A table of contents would be of great use in this stage when you try to recommend this stuff to other people!
About the post: I guess you are not completely ruling out the role of physics in the final understanding of consciousness, because even though QM may not play an important role, a deeper understanding of spacetime, may... But hopefully it all lies in mathematics as Hofstadter and Goerzel suggests, that would be the most elegant and also practical reality, sadly reality does not obey hopes...
I also hope that there is not a general bias amongst scientists familiar with physics towards having consciousness interfere with physics, because they are so used to have them in different domains, and because so much confusion has arisen when you have not made this distinction clear. And because so many sloppy theories are riding on this hypothesis that is so much more intuitive. It could still be the case that fundamental physics can explain some aspect of say the hard problem. There seems to be two competing aesthetics in the matter of consciousness and physics, and I am still not convinced it is more than aesthetics, therefor I wait in taking a stance myself.
But I am so grateful Eli convinced me of the impossibility of Zombies, I used to be consider epifenomenalism. But now I know better. But that leads me to the inevitable question of the functional role of qualia. Why chocolate tastes good, which seems to have a causal effect on me wanting to eat it, rather than me just having chocolate eating behavior whiteout the intermediate of qualia. Does a dog have qualia behaviour or just eating beahviour when it finds something good? Qualia and consciousness seems to be an internal monitoring mechanism with very precise input from evolutionary adaptive qualia(like emotions, strong tastes, sensations of the body parts of the opposite sex), but for what purpose, and why the qualia, and what are the effects on neurocomputation? Or if it IS the neurocomputation, then why am I experiencing such a nice whole and not a lot of different processes in my brain, why does it seem that I am only experiencing some output of the work of my brain? Why do I need to expereience anything anyway? What does the resource limitations in my consciousness depend on. Why can´t I experiences all my memories at the same time. Is counsciousness a separate brainsystem(like the thalamocortical loop, bioelectromagnetic field or even quantum mind) or just a product of the whole brain working together. If it is a separable brain system, what are the measurable causal effects. If it is not, what distinguishes conscious from non conscious processing. If consciousness is a mathematical phenomenon, then still, why is qualia so rich and strongly qualitative, compare the feeling of hunger to the color red or to the sound of a piano? Maybe it is just the way information feels in the universe. Which leads to the question if all information feels itself, does a book feel the structure of the words in it, if not then what makes information feel itself, a strange loop? Well what about a TV set and a camera pointing towards each other. But what is it with a universe that allows such strange phenomena. Well anything is strange to us really, and nothing is really strange to the universe. We will probably always find everything rather absurd but wonderful if we think really deep about it, even if we are no longer as confused in our understanding as we are now. But the universe remains neutral on strangeness. "Since the beginning not one unusual thing has happened"
comment by Rolf_Nelson2 · 2008-04-25T10:36:58.000Z · LW(p) · GW(p)
can you tell me why the subjective probability of finding ourselves in a side of the split world, should be exactly proportional to the square of the thickness of that side?
Po'mi runs a trillion experiments, each of which have a one-trillionth 4D-thickness of saying B but is otherwise A. In his "mainline probability", he sees the all trillion experiments coming up A. (If he ran a sextillion experiments he'd see about 1 come up B.)
Presumably an external four-dimensional observer sees it differently: He sees only one-trillionth of Po'mi coming up all-A, and the rest of Po'mi saw about 1 B and are huddled in a corner crying that the universe has no order. (Maybe the 4D observer would be unable to see Po'mi at all because Po'mi and all other inhabitants of the lawful "mainline probablity" that we're talking about have almost infinitesimal thickness from the 4D observer's point of view.)
If I were Po'mi, I would start looking for a fifth dimension.
comment by Hopefully_Anonymous · 2008-04-25T12:06:30.000Z · LW(p) · GW(p)
"But I am so grateful Eli convinced me of the impossibility of Zombies". What does that really mean? That he convinced of the impossibility of something physically identical to you, that behaves just like you, that claims to be conscious? Because that seems to be a silly construct well beyond our discernment technology (whether or not something is "physically identical" to you), and connectedly, not of much practical interest.
Or did he convince you what some people want to seem to believe, even if the evidence doesn't extend that far: that something that would convince the smartest of us today that it's conscious may not actually have your (or more to the point, my) subjective conscious experience, but may be in a real time equivalent to sleep walking and sleep talking or in a real time equivalent to an alcohol blackout -is impossible or unlikely to the point of near impossibility.
That zombie has been branded as the former thing, of little practical concern, rather than the latter thing, which I think would be of reasonable (and possibly near-term) practical concern to us is very annoying to me, because I think it would be a great term for the latter thing.
comment by Sebastian_Hagen2 · 2008-04-25T13:13:01.000Z · LW(p) · GW(p)
Good writing, indeed! I also love what you've done with the Eborrian anzrf (spoiler rot13-encoded for the benefit of other readers since it hasn't been mentioned in the previous comments).
The split/remerge attack on entities that base their anticipations of future input directly on how many of their future selves they expect to get specific input is extremely interesting to me. I originally thought that this should be a fairly straightforward problem to solve, but it has turned out a lot harder (or my understanding a lot more lacking) than I expected. I think the problem might be in the group of 500,003 brains double-counting anticipated input after the merge. They don't stay exactly the same through the merge phase; in fact, for each of the 500,000 brains in green rooms, the re-integrated previously-in-green-rooms brain only depends to a very small part on them individually. In this particular case, the re-integrated brain will still be very similar to each of the pre-integration brains; but that is just a result of the pre-integration brains all being very similar to each other. Treating the re-integrated brain as a regular future-self for the purposes of anticipating future experience under these conditions seems highly iffy to me.
comment by poke · 2008-04-25T13:27:52.000Z · LW(p) · GW(p)
Robin Brandt,
I think "chocolate eating behavior" already does "whiteout the intermediate of qualia." We've just confused the issue by associating "the experience I have when eating chocolate" with things generally considered "good." Your experience of eating chocolate is just the sum of cognitive and physiological changes associated with eating chocolate. If we performed an experiment where you were subjected to a pain stimulus but then we subtracted, one by one, the various physiological and cognitive aspects of pain, I think you would be convinced that there isn't a pain qualia per se (that it is rather the sum of these aspects and no one of them is more or less pain-proper than the other).
comment by Ben_Jones · 2008-04-25T13:32:50.000Z · LW(p) · GW(p)
The more I think about consciousness, the more I think it's ridiculous to have anything but the sparsest take on how to consider it. We should eschew anthropocentrism (mind-centrism? mind projection?) at every step. While it may have some nasty-sounding consequences in areas like ethics, I can't convince myself that conscious minds have any special place in the universe, for any reason. It’s this century’s answer to having the Earth at the centre of the universe.
To relate my point to the parable: I would say that if you have all the information about a brain-split - if you know the exact position and momentum of every particle at every point - but you're still asking 'yes, but when does one consciousness become two?' then you're asking a wrong question. The consequence of this is removing that central name tag called ‘+/-consciousness’ in your neural ‘attributes of consciousness’ network.
When you think about it, drawing a line around all your neurons etc and saying 'this is me’ is ridiculous. What about the dead cells? or the cells that have no observable effect? how many neurons can I remove before you stop being 'you'? If you claim there's a ‘self’ inside your head that emerges, from all the wetware, unified and irreducible, you’re setting yourself up for impossible questions just like the poor Ebboreans. Difficult though it is, you have to drop the mind-centrism. Am I saying that consciousness is an illusion? That’s not how I’d put it – after all, illusions are things that minds perceive. But what is, is real. Consciousness is. It’s just not ‘special’. You have no more ‘weight’ than a copy of yourself that assembles itself at random for a fraction of a second in a distant galaxy. Sorry. (By this rationale, ‘zombies’ are a nonsense too. )
When you ask ‘Why is red red?’, for me you’ve already projected your mind onto the territory. Red isn’t red in the world. It’s red in your map as a result of how your brain entangles itself with photons at a certain wavelength - an artefact of evolution - and I don’t need to explain that any more than I need to explain why you want your eggs sunny side up. Don’t mistake confusion and gaps in our knowledge for mysticism.
Really good stuff, Eliezer. Why do I get the feeling that we won't ever get to hear what the big wonderful theory was? I'm just on the last chapter of GEB, and I've really enjoyed it, but I've no doubt your final piece will be entirely your own - it certainly deserves to be. That said, I like the sound of Jaynes, Einstein, Bayes: A Rational Steel Katana....
comment by steven · 2008-04-25T13:53:49.000Z · LW(p) · GW(p)
In today's post I would like to see De'da and/or Wa'da ask Ha'ro, if worlds are equiprobable, 1) why we're not in a near-maximum-entropy universe, and 2) if we can win the lottery by burning stuff afterward. (Maybe there are legitimate answers, I don't know.)
comment by Caledonian2 · 2008-04-25T14:43:27.000Z · LW(p) · GW(p)
That zombie has been branded as the former thing, of little practical concern, rather than the latter thing, which I think would be of reasonable (and possibly near-term) practical concern to us is very annoying to me, because I think it would be a great term for the latter thing.Then go complain to Chalmers, because he's the one who established that term! We had nothing to do with it.
if worlds are equiprobable, 1) why we're not in a near-maximum-entropy universeIt is highly unlikely that a given person who purchased a lottery ticket will win. If a person receives data indicating that they have won, though, the unlikeliness of that outcome is not grounds for discarding the information out of hand. Sometimes, people win.
It seems to me unlikely that a functioning organism such as ourselves would be able to persist for very long in a near-maximum-entropy universe. Even if we presume the local space were relatively and anomalously ordered, it is far more likely for that to happen at a point in time where the universe as a whole is relatively ordered than at a point where everything else is a mess.
comment by steven · 2008-04-25T15:15:41.000Z · LW(p) · GW(p)
Caledonian, ordinarily that would be true, but the point is that in the MWI the number of worlds increases exponentially as a function of entropy, so very soon high-entropy worlds outnumber low-entropy worlds by a factor of (if I'm not mistaken) ten-to-the-power-avogadrillions. As just one example, there should be a lot more Everett worlds where we used up all the fossil fuels than where we didn't. AFAIK that's still true if you consider only non-mangled worlds, but maybe I misunderstood the model and the number of non-mangled worlds actually stays constant under entropy increase.
comment by Robin_Brandt · 2008-04-25T15:53:39.000Z · LW(p) · GW(p)
Hopefully Anonymous:
It means that I used to belive the experience of consciousness/qualia/the hard problem is just like the sound of the heart, i.e. whitout any functional role. I never thought zombies would really be possible... just in principle. And I had my doubts even then. Don´t laugh at me because the functional role of qualia is not easy to understand.
poke:
I think you missed the point here. The question is why choclate eating feels like anything, it seems that the qulia should be unessecary for the brain function of chocolate eating behavior. The same goes with orgasm. They seem to be things that try to guide one part of the brain system with input with qualia from another in order to guide our behavior towards thinks that statistically makes us survive and reproduce. If qualia has no functional role, then the zombie argument is sound. Or this is how I have understood it attending consciousness studies here at Skövde with professor Antti Revonsuo who published his book Inner Pressence on MIT Press. If qualia would just be a confusion it seems highly unlikely that evolution would have spent any time making qualias just for the fun of it, and qualia has to be a real event taking place in the universe, a real event that needed some energy and information content to produce.
To deny qualia today is like the behaviorists who denied cognitive processes yesterday. You are smarter than that!
Or it may be that some of you actually don´t experience qualia, sometimes I encounter people who I really doubt experiences qualia in the normal way, especially in the autism spectrum. So if you suffer from any disorder, please mention that if you are talking about qualia. But my quess is that everybody has qualia, it may just be easier to deny them if they are not connected to emotions.
comment by Robin_Brandt · 2008-04-25T16:58:14.000Z · LW(p) · GW(p)
Also about the chocolate eating, you can get addicted so that you no longer even need the qualia keep on eating it. There seems to be a distinction between qualia induced choclate eating and addictive choclate eating where you continue eating although it does not taste so good anymore, wich if you notice the lameness of the qualia may make you stop eating. Why is that, if qualia is a mere confusion, there should not be such distinctions. It seems not rational to spend energy on producing qualia if they are not useful in any sense. But useful for what? Still qualia affecting our decisions seems rather impossibe to me, but that has to be a fact about my own confusion not about the territory.
comment by Caledonian2 · 2008-04-25T19:42:24.000Z · LW(p) · GW(p)
To deny qualia today is like the behaviorists who denied cognitive processes yesterday. You are smarter than that!Without being able to offer functional criteria for judging whether 'cognitive processes' exist, it would certainly be inappropriate to talk about them.
Cognitive psychologists not only managed to produce an experiment that would distinguish between "having cognitive processes" and "not having cognitive processes", they performed it and resolved the dispute.
What experimental results would be enough to convince you that 'qualia' did not exist?
comment by Mitchell_Porter_(posted_by_Eliezer) · 2008-04-26T05:16:39.000Z · LW(p) · GW(p)
As I wrote part of this post to explicitly discuss Mitchell Porter's position, I think it only fair to post Mitchell Porter's comment here, where it should be more at home than in "On Philosophers". -- Eliezer Yudkowsky
**
Mitchell Porter commented:
Before I get lost in these semantic and epistemic complexities, I will say once again what the problem is.
We are endeavoring to interpret the wavefunctions or state vectors of quantum mechanics: to form a hypothesis about the reality they describe. The hypothesis is: before decoherence there is one "quantum world", after decoherence there are many quantum worlds. As the difference between "one world" and "more than one world" is discontinuous, but the process of decoherence is continuous, with no sharp boundary between before and after, I asked exactly where the transition from one world to more than one world occurs. The reply was that that is not an issue, since the answer would make no difference to the argument in the papers. I conceded that it makes no difference to this particular argument, but the issue itself must be faced; the existence of these worlds, if they are to be taken seriously, must be an objective matter.
Somehow, having attempted to argue for that last proposition, I find myself being asked to define what I mean by "existence", to accept that someone's existence can be "vague", and who knows what else is going to come up. I accept the desirability of trying to elucidate fundamental concepts as thoroughly as possible. But can I first ask: If a person said that according to their theory of the universe, at one time you have one of something, and later on you have many copies of that same thing, but there's no particular moment in time when the one becomes the many, and that doesn't matter because the something only has a vague, fuzzy existence... wouldn't you think that the theory might have a few problems, or at least be missing a part?
Everything I have said about worlds, and observers in worlds, and about the certainty of one's own existence as an individual observer, has been meant to drive that home. That chain of relationships is the detailed reason why it is unacceptable to have a blase attitude towards the conditions of existence of quantum worlds. They must be regarded as existing or not existing, in a completely objective, absolute, non-relative way, or the concept becomes a nonsense, because worlds must play the role of hosting entities whose existence is definitely not vague or relative, namely, us.
Does no-one understand or sympathize with this line of thought?
I will get on with the philosophy in a moment. But I ask that those of you who may find yourselves in a protracted debate with me over these tangential questions, please consider anew the foregoing argument and ask yourself whether it is desirable or even possible to settle for a vague notion of "world", given the theoretical burden it has to bear.
Caledonian asks what I mean by "existence". I confess that I am unable to define it without using a synonym, which is not much of a definition. There may be quite a few similar basic indefinables, which we nonetheless manage to talk about; "negation" may be another example. It seems that all I can do is talk about it, and hope some recognition dawns. I know I already have a disagreement with Caledonian in this matter, because earlier this month he wrote here that existence is relative and depends on the possibility of interaction, something I would never say, because it confuses existence per se with something like knowability - the epistemic grounds whereby one observer may assert of one thing that it does indeed exist. We who live now, our existence was not knowable to anyone who lived a thousand years ago. Nonetheless, we do exist, here and now, and it is a fallacy to relativize our existence, and say "we exist for each other, but we don't exist for those people in the past". It is a basic confusion of knowability with reality.
Now, Unknown, what am I to do with you? Your line is that existence is a vague concept because I cannot define it without being circular, or that I cannot define it in a way which offers a clear decision procedure for existence. My line would be that we all know perfectly well what "existence" refers to - the property of being there, the property of being a part of reality, the property of not being nonexistent - but that the metaphysical depths of its nature are not so obvious. Again, one is constantly making implicit judgements about what does and does not exist. Does al Qaeda exist? Does Xenu exist? Does the special discount on milk at the corner store still exist? Existential judgements are ubiquitous in human thought. We all possess a basic facility with the concept. Does the inability to crisply define it or place it in an ontological scheme mean that one only has a vague concept of existence? I don't think so, because I think the criterion of vagueness in a concept is that its referent, the specific thing which it designates, is underdetermined (i.e. there are several different things it might be referring to), not that the nature of the referent remains incompletely specified. I think the particular referent of the human concept of existence is unambiguously known, but the nature of that referent may be obscure to the human mind. But this is a complicated matter.
And one more time: this metaphysics is an interesting and even vital topic, but it is somewhat of a tangent from the main issue, which is the meaning of "world" in many worlds.
comment by Unknown · 2008-04-26T07:23:58.000Z · LW(p) · GW(p)
"But can I first ask: If a person said that according to their theory of the universe, at one time you have one of something, and later on you have many copies of that same thing, but there's no particular moment in time when the one becomes the many, and that doesn't matter because the something only has a vague, fuzzy existence... wouldn't you think that the theory might have a few problems, or at least be missing a part?"
No. Robin implicitly offered an example: if a galaxy were to divide into two galaxies, it would be impossible to assign an exact moment when the one became two. Nonetheless, there clearly would be a time when it was one, and clearly a time when it was two.
As for the vagueness of existence, it is also vague in having an underdetermined referent. For example, does the truth of a statement exist? If so, then "exists" is underdetermined, because "truth" is underdetermined. The latter is necessary because if you attempt to give a complete definition of truth, you will fall into contradictions (e.g. "this statement is not true".)
comment by Nick_Tarleton · 2008-04-26T13:21:07.000Z · LW(p) · GW(p)
I'm sympathetic to Mitchell's position, and would note that anthropic reasoning requires a definite answer to "what observers exist and in what proportion?"
comment by Unknown · 2008-04-26T17:07:44.000Z · LW(p) · GW(p)
Nick, you are right about the definite proportion, but this doesn't require definite quantities, since the proportion 50 to 100 is the same as the proportion 100 to 200. So anthropic reasoning only requires definite proportions, not definite quantities.
comment by Nick_Tarleton · 2008-04-26T17:25:06.000Z · LW(p) · GW(p)
Why do you need anticipation to express surprise at the orderliness of the universe? Thinking like reality would mean abandoning "personal continuity" and just talking about frequencies of experiences, and you can still express your surprise at finding such an orderly experience.
comment by mitchell_porter2 · 2008-04-27T04:51:39.000Z · LW(p) · GW(p)
Unknown: suppose I say there's a central singularity in each galaxy, so there's one singularity to begin with, and two at the end, but there's no exact moment when one singularity becomes two. That's what you're doing when you say there's an observer in each world, and then vague out on the concept of "world".
Does the truth of a sentence exist? A proper discussion of that might explode the boundaries of this blog again. But I'll just say that I had ostensive definitions in mind, when I said that the referent of a concept may be known even when its nature is not. If I point to a light in the sky and say, "that's Venus", you know what "Venus" refers to, even though you may not know much about it. And both "existence" and "truth" similarly admit of "definition"-by-example, i.e. by exhibition of an instance.
comment by Eliezer Yudkowsky (Eliezer_Yudkowsky) · 2008-04-27T05:05:11.000Z · LW(p) · GW(p)
Tarleton: Thinking like reality would mean abandoning "personal continuity" and just talking about frequencies of experiences, and you can still express your surprise at finding such an orderly experience.
Sure, if I had a well-defined way to talk about frequency (or weight or measure) of experience, it would be a lot easier to toss "personal continuity" out the window. I want to save the notion of conditional measure if I can, but I suppose I could live without it.
comment by Caledonian2 · 2008-04-28T15:46:18.000Z · LW(p) · GW(p)
I know I already have a disagreement with Caledonian in this matter, because earlier this month he wrote here that existence is relative and depends on the possibility of interaction, something I would never say, because it confuses existence per se with something like knowability
No. That is completely wrong.You are confusing what things ARE, with what we THINK them to be. This is a common problem when dealing with models of reality (in which we exist), models in which we (as external observers) 'know' everything about the model; we tend to confuse the 'we' within the model, which is ignorant, with the 'we' looking at the model, which is essentially omniscient. (This is a simplification, as the full details are beyond the scope of this thread.)
Whether a thing exists has nothing to do with what we know. Whether we can assert that a thing exists has everything to do with what we know. It is entirely possible for properties of the system to be forever unknowable for particular entities within that system, or even entities in general within that system, and still exist. But those entities are not entitled to make any claims about the existence of said properties.
comment by Richard_Hollerith2 · 2008-04-30T07:04:54.000Z · LW(p) · GW(p)
If I throw away the notion of subjective anticipation, then how do I differentiate the chaotic universe from the orderly one?
One can differentiate in a sense with the relevancy razor. The conclusion given by the relevancy razor in this case is that it is safe to assume that you live in the orderly universe because if you lived in the chaotic one, then you have no hope of affecting reality -- no hope of achieving any goal or carrying through any plan.
The relevancy razor is a principle of general applicability much like Occam's Razor is a principle of general applicability.
Here is a statement of the relevancy razor:
Thinking entails the contemplation of "possible worlds". It may be that you are unsure of the nature of the world you find yourself in or it may be that you are facing a decision, and how you decide will determine which possible world you will end up in. In either case, you have to think about possible worlds. The relevancy razor says that you do not have to contemplate any possible world in which you -- the current you, not the you of the future -- cannot affect reality. (Moreover, the greater your ability to affect reality in a possible world, the more attention you should pay to that possible world -- just as the greater the probability of a possible world, the more attention you should pay to it.)
One other thing. Asking, What is the difference in anticipated experience between X and Y? is a useful and powerful question. I applaud Eliezer in encouraging its use.
But there is another question that is just as useful and powerful, namely, What can I predict or control in the objective world if X that I cannot predict or control if Y? (John David Garcia has encouraged the use of this question since the early 1980s.)
I prefer the second question because it does not tend to pull one into viewing subjective experience as what ultimately matters.
If you're joining the conversation late, then hi, I'm Richard Hollerith, and I want you to believe that what matters in the end about you is your effect on reality, not your subjective experience.
(I do not say that subjective experience should be completely ignored: subjective experience can yield valuable information that is impractical or too expensive to acquire any other way, and that valuable information can, in turn, be used to affect reality, whichyou lived in the chaotic one, then you have no hope of affecting reality -- no hope of achieving any goal or carrying through any plan.
I propose the relevancy razor as a principle of general applicability much like Occam's Razor is a principle of general applicability.
Here is a statement of the relevancy razor:
Thinking entails the contemplation of "possible worlds". It may be that you are unsure of the nature of the world you find yourself in or it may be that you are facing a decision, and how you decide will determine which possible world you will end up in. In either case, you have to think about possible worlds. The relevancy razor says that you do not have to contemplate any possible world in which you -- the current you, not the you of the future -- cannot affect reality. (Moreover, the greater your ability to affect reality in a possible world, the more attention you should pay to that possible world -- just as the greater the probability of a possible world, the more attention you should pay to it.)
One other thing. Asking, What is the difference in anticipated experience between X and Y? is a useful and powerful question. I applaud Eliezer in encouraging its use.
But there is another question that is just as useful and powerful, namely, What can I predict or control in the objective world if X that I cannot predict or control if Y? (John David Garcia has encouraged the use of this question since the early 1980s.)
I prefer the second question because it does not tend to pull one into viewing subjective experience as what ultimately matters.
If you're joining the conversation late, then hi, I'm Richard Hollerith, and I want you to believe that what matters in the end about you is your effect on reality, not your subjective experience.
(I do not say that subjective experience should be completely ignored: subjective experience can yield valuable information that is impractical or too expensive to acquire any other way, and that valuable information can, in turn, be used to affect reality, which, again, is the purpose of life.)
comment by Richard_Hollerith2 · 2008-04-30T07:19:28.000Z · LW(p) · GW(p)
Oh crap: I thought I was being careful, previewing before posting, but my comment got jumbled. I'll upload the unjumbled version now, and hope that a moderator will delete what I just uploaded (and this short "oh crap" too).
comment by Richard_Hollerith2 · 2008-04-30T07:23:43.000Z · LW(p) · GW(p)
If I throw away the notion of subjective anticipation, then how do I differentiate the chaotic universe from the orderly one?
One can differentiate with the relevancy razor. The conclusion given by the relevancy razor in this case is that it is safe to assume that you live in the orderly universe because if you lived in the chaotic one, then you have no hope of affecting reality -- no hope of achieving any goal or carrying through any plan.
The relevancy razor is a principle of general applicability much like Occam's Razor is a principle of general applicability.
Here is a statement of the relevancy razor:
Thinking entails the contemplation of "possible worlds". It may be that you are unsure of the nature of the world you find yourself in or it may be that you are facing a decision, and how you decide will determine which possible world you will end up in. In either case, you have to think about possible worlds. The relevancy razor says that you do not have to contemplate any possible world in which you -- the current you, not the you of the future -- cannot affect reality. (Moreover, the greater your ability to affect reality in a possible world, the more attention you should pay to that possible world -- just as the greater the probability of a possible world, the more attention you should pay to it.)
One other thing. Asking, What is the difference in anticipated experience between X and Y? is a useful and powerful question. I applaud Eliezer in encouraging its use.
But there is another question that is just as useful and powerful, namely, What can I predict or control in the objective world if X that I cannot predict or control if Y? (John David Garcia has encouraged the use of this question since the early 1980s.)
I prefer the second question because it does not tend to pull one into viewing subjective experience as what ultimately matters.
If you're joining the conversation late, then hi, I'm Richard Hollerith, and I want you to believe that what matters in the end about you is your effect on reality, not your subjective experience.
(I do not say that subjective experience should be completely ignored: subjective experience can yield valuable information that is impractical or too expensive to acquire any other way, and that valuable information can, in turn, be used to affect reality, which again, is the purpose of life.)
comment by TruePath2 · 2008-05-04T21:19:01.000Z · LW(p) · GW(p)
Bravo, great post. It's an argument I've been trying to make forever but never seem to be able to do so in a way that people understand. You seem to have managed what was beyond me.
Hollerith: What subjective experiences will exist in a particular world is an objective question. Now that is indeed different from what experiences I should expect to have but still something we can't solve.
comment by mitchell_porter2 · 2008-05-17T07:12:28.000Z · LW(p) · GW(p)
A belated meta-response to Caledonian: this is your earlier remark to which I referred. We may have no more than a terminological difference. As I said above, I would (hope to) never say "A exists relative to B", only that A was detectable, rationally inferable, etc., relative to B. It's too confusing to use "existence" as if it only means "epistemically assertible existence".
comment by rosyatrandom · 2009-04-03T14:55:35.000Z · LW(p) · GW(p)
Annoying question:
How does an Ebborian fission into more than 2 parts? Surely there aren't enough organs to go round! Unless you allow for unconscious rounds of regrowth and refissioning...
comment by Furcas · 2009-06-13T01:07:19.692Z · LW(p) · GW(p)
So now suppose that my 500,000 green selves are reunited into one Ebborian, and my 3 red selves are reunited into one Ebborian. Have I just sent nearly all of my "subjective probability" into the green future self, even though it is now only one of two?
With only a little more work, you can see how a temporary expenditure of computing power, or a nicely refined brain-splitter and a dose of anesthesia, would let you have a high subjective probability of winning any lottery. At least any lottery that involved splitting you into pieces."
I don't understand this part; someone explain it to me, please!
Replies from: thomblake↑ comment by thomblake · 2012-04-18T21:02:08.735Z · LW(p) · GW(p)
Think of the Monty Hall problem. According to the lines just above those, those 500,000 selves have greater probability mass than the 3 red selves. But then combining them, you have a single green self with a greater probability mass than the single red self.
For the other part, see The Anthropic Trilemma about the Quantum Lottery thought experiment.
comment by Sengachi · 2018-02-03T06:12:30.558Z · LW(p) · GW(p)
Just so you all know, Clifford Algebra derivations of quantized field theory show why the Born Probabilities are a squared proportion. I'm not sure there's an intuitively satisfying explanation I can give you for why this is that uses words and not math, but here's my best try.
In mathematical systems with maximal algebraic complexity for their given dimensionality, the multiplication of an object by its dual provides an invariant of the system, a quantity which cannot be altered. (And all physical field theories (except gravity, at this time) can be derived in full from the assumption of maximal algebraic complexity for 1 positive dimension and 3 negative dimensions). [Object refers to a mathematical quantity, in the case of the field theories we're concerned with, mostly bivectors].
The quantity describing time evolution then (complex phase amplitudes) must have a corresponding invariant quantity that is the mod squared of the complex phase. This mod squared quantity, being the system invariant whose sum describes 'benchmark' by which one judges relative values, is then the relevant value for evaluating the physical meaning of time evolutions. So the physical reality one would expect to observe in probability distributions is then the mod squared of the underlying quantity (complex phase amplitudes) rather than the quantity itself.
To explain it in a different way, because I suspect the one way is not adequate without an understanding of the math.
Clifford Algebra objects (i.e. the actual constructs the universe works with, as best we can tell) do not in of themselves contain information. In fact, they contain no uniquely identifiable information. All objects can be modified with an arbitrary global phase factor, turning them into any one of an infinite set of objects. As such, actual measurement/observation of an object is impossible. You can't distinguish between the object being A or Ae^ib, because those are literally indistinguishable quantities. The object which could be those quantities lacks sufficient unique information to actually be one quantity or the other. So you're shit out of luck when it comes to measuring it. But though an object may not contain unique information, the object's mod squared does (and if this violates your intuition of how information works, may I remind you that your classic-world intuition of information counts for absolutely nothing at the group theory level). This mod squared is the lowest level of reality which contains uniquely identifiable information.
So the lowest level of reality at which you can meaningfully identify time evolution probabilities is going to be described as a square quantity.
Because the math says so.
By the way, we're really, really certain about this math. Unless the universe has additional spatial-temporal dimensions we don't know about (and I kind of doubt that) and only contains partial algebraic complexity in that space (and I really, really doubt that), this is it. There is no possible additional mathematical structure with which one could describe our universe that is not contained within the Cl_13 algebra. There is literally no mathematical way to describe our universe which adequately contains all of the structure we have observed in electromagnetism (and weak force and strong force and Higgs force) which does not imply this mod squared invariant property as a consequence.
Furthermore, even before this mod squared property was understood as a consequence of full algebraic complexity, Emmy Noether had described and rigorously proved this relationship as the eponymous Noether's theorem, confirmed its validity against known theories, and used it to predict future results in field theory. So this notion is pretty well backed up by a century of experimental evidence too.
Tl;DR: We (physicists who work with both differential geometries and quantum field theory and whom find an interest in group theory fundamentals beyond what is needed to do conventional experimental or theory work) have known about why the Born Probabilities are a squared proportion since, oh, probably the 1930s? Right after Dirac first published the Dirac Equation? It's a pretty simple thing to conclude from the observation that quantum amplitudes are a bivector quantity. But you'll still see physics textbooks describe it as a mystery and hear it pondered over philosophically, because propagation of the concept would require a base of people educated in Clifford Algebras to propagate through. And such a cohesive group of people just does not exist.
Replies from: Dacyn↑ comment by Dacyn · 2018-02-15T00:34:54.225Z · LW(p) · GW(p)
I don't know much about Clifford algebras. But do you really need them here? I thought the standard formulation of abstract quantum mechanics was that every system is described by a Hilbert space, the state of a system is described by a unit vector, and evolution of the system is given by unitary transformations. The Born probabilities are concerned with the question: if the state of the universe is the sum of where
are orthogonal unit vectors representing macroscopically distinct outcome states, then what is the subjective probability of making observations compatible with the state
? The only reasonable answer to this is
, because it is the only function of
that's guaranteed to sum to
based on the setup. (I don't mean this as an absolute statement; you can construct counterexamples but they are not natural.) By the way, for those who don't know already, the reason that
is guaranteed to sum to
is that since the state vector
is a unit vector,
Of course, most of the time when people worry about the Born probabilities they are worried about philosophical issues rather than justifying the naturalness of the squared modulus measure.
comment by Basil Marte · 2019-02-10T00:26:50.892Z · LW(p) · GW(p)
"There's no third-party experiment you can perform to tell you the answer."
While it's irrelevant to the anthropics/quantum physics debate, I almost immediately thought: let's put an electrode onto one side of an Ebborian brain-paper, and give it a train of pulses while it splits. Ask the Ebborian that "inherits" the other side of the brain, how many pulses it experienced.
comment by dadadarren · 2022-06-09T18:02:38.686Z · LW(p) · GW(p)
The questions surrounding conscious experiences and splits, e.g. which color "I" will likely see afterward, etc, intrinsically use the concept of a first-person perspective. I.e. they take which Ebborian is "I" as something inherently apparent. But physics doesn't answer "why you are you and I am me?", or why "I am experiencing the world from the perspective of this particular object?". It will be a big surprise if the Ultimate Grand Unified Theory of Everything could answer this. Put it another way, if it does answer that, then Po'mi's questions would have been thoroughly explained by the UGUTE.
If the first-person perspective is not explained by physics, and at the same time plays an integral part in world modeling: -after all, it's all based on the experiences of reading dials and turning knobs-, then maybe the right way is to treat it as something fundamentally primitive. Something all physical reasoning ought to be conducted from.