As a young grad student, I remember going to a talk by Bennett where he explained how a Quantum Computer allows manipulation in a 2^N dimensional hilbert space, while the outputs measurements give you only N bits of information. The trick is to somehow encode the result in the final N bits.
I felt this was a much better layman explanation of what a quantum computer does than simply saying a quantum computer runs all possible paths in parallel.
> I felt this was a much better layman explanation of what a quantum computer does than simply saying a quantum computer runs all possible paths in parallel.
I don't think we get rid of the CPU. But the relationship will be inverted. Instead of the CPU calling the GPU, it might be that the GPU becomes the central controller and builds programs and calls the CPU to execute tasks.
How do you win moving your central controller from a 4GHz CPU to a multi-hundred-MHz single GPU core?
If we tried this, all we'd do is isolate a couple of cores in the GPU, let them run at some gigahertz, and then equip them with the additional operations they'd need to be good at coordinating tasks... or, in other words, put a CPU in the GPU.
Surprise: there are already CPUs in the GPU - they're called things like "Command Processor" (but not only) - they're often tiny in-order ARM or RISC-V cores.
Sounds reminiscent of the CDC 6600, a big fast compute processor with a simple peripheral processor whose barreled threads ran lots of the O/S and took care of I/O and other necessary support functions.
What if we create a situation in a lab that can be labelled as a collapse of the wave function by interaction with a macroscopic object. Except the macroscopic object is under our control and we can reverse the collapse.
The part that I have trouble wrapping around with many worlds interpretation is how I as an observer end up in one of the many bifurcations. Any links you can share that will help me with understanding that is welcome!
The Stanford Encyclopedia of Philosophy (https://plato.stanford.edu/entries/qm-manyworlds/) goes into this in some depth, and it seems like the right way to think about it is say that "I" in one branch is a different entity than the "I" in a different branch. I have somehow not been able to grok it yet.
And I agree about the naming. I really dislike the name "many worlds interpretation", which seems to imply that we have to postulate the existence of these additional worlds, whereas in fact they are branches of the wavefunction exactly predicted by standard quantum mechanics.
> The part that I have trouble wrapping around with many worlds interpretation is how I as an observer end up in one of the many bifurcations.
Pour water down a hill. Water clings to water, and we have hills that already have lots of correlations. We get streams that break up into multiple streams.
How did one stream end up where it is? It seems like a good question, but it is circular. The stream is defined by where it is. You are here (in some circumstance), because the version of you in this circumstance is you.
A transporter accident that creates several versions of you, on several planets with difference colors, doesn't need to explain to each version how they ended up at a planet with their color. Even if for a particular copy, it seems like there should be an answer why they showed up on a planet of a particular specific color. The "why" is just, all paths were taken.
What you said here makes sense. Forgive me, but I have trouble even articulating what it is that I don’t understand correctly.
Maybe what I meant was this: if I perform a quantum experiment where the spin measurement of an electron could be spin up or spin down, the future me would end up in one of two branches: I measure spin up, or I measure spin down. There wouldn’t be any possible world where I measure a superposition of spin up and spin down, because such a a state is going to decohere rapidly. This makes sense. What I’m unable to grasp is that even though the wave function of the universe contains both branches, “I” somehow experience only one of the two branches.
The answer to that I guess if that the two branches are nearly orthogonal they will merrily evolve independent of each other. But somehow “I” only experience only one of them.
Sorry for the rambling. I’m not able to articulate what I don’t understand.
> The future me would end up in one of two branches: I measure spin up, or I measure spin down.
The future "you's" would each see spin up, and spin down, respectively.
We are just as quantum as what we measure. There isn't a scale where entanglement and superposition turn into something else. No classical vs. quantum atoms.
Just as an up-spin qubit touching an up/down qubit results in an up-up qubit pair in superposition with an up-down superposition, conserving the qubit, when we touch a qubit we get "us"-up and "us"-down versions.
No information is created. None is destroyed. We experience a correlation = "collapse" (both versions of us), but the quantum information just continues on as before, qubit conserved.
>But somehow “I” only experience only one of them.
Using the example from the other comment, "You" are the stream and not a drop of water in it.
In other words, you are not an entity with unique identity that traverse the tree of possibilities. You are part of the tree, actually, part of a branch. The branch's existence and your existence implies each other. Like your hand's existence and your existence imply each other. Your hand could not have existed without you (a similar looking one could. but it wouldn't be yours). And you without your hand (you could have had a different hand, but that wouldn't be "you" (which also includes the hand))
The problem with Many Worlds is that it doesn't place a bound on the number of worlds, so you can't derive the Born Rule from it.
That's quite a serious issues. And arguments against that - like Self-Locating Uncertainty, or Zurek's Envariance - look suspiciously circular if you pull them apart.
There's also the issue that if you don't have a mechanism that constrains probability, you can't say anything about the common mechanism of any of the worlds you're in. Your world may be some kind of lottery-winning statistical freak world which happens to have very unusual properties, and generalising from them is absolutely misleading.
There's no way of testing that, so you end up with something unfalsifiable.
> The problem with Many Worlds is that it doesn't place a bound on the number of worlds, so you can't derive the Born Rule from it.
I have no idea what this means.
Is there a bound on anything in reality, in terms of scale? Beyond its own laws?
I am reminded of how often in history, too much time, or too much scale, were unsuccessful arguments against many theories we accept today. Those critiques died without any need for special arguments, because they don't have a logical basis.
Also, there are not a number of many "worlds". That is a reflection of poor naming. There is an interleaving of all interactions, so if you zoom out, a smeared landscape across all configurations, from the plank scale up.
Because the connections involve both intersection (entanglement) and union (alternate paths), we get bifurcation of classical sized paths (dense entanglements), while the individual particles continue unconcerned by how they appear to create different classical histories at large scale.
And yes it is experimentally validated. This is the theory that everyone accepts in the lab, even as larger scales of experiment continue to progress.
But some people have difficulty believing/visualizing that it continues to work at larger scales. Despite no scale limitation in the theory, no scale related violations ever suggested experimentally, and the strong likely that scale limitations would produce new physics in at-scale observations of our cosmos if they did exist.
> how I as an observer end up in one of the many bifurcations..
Just a pleb here, but that does not stop me from thinking about it..
I think your consciousness is a function of the world you belong. So asking why your are in a certain world, and not in other, is like asking why you are born to your specific parents, and not to others.
So you don't end up in some fork, by a roll of dice, you are already confined to, and defined by a single branch.
So I don't think the exact "you" don't exist in another branch. But another consciousness that only differ from "you" by only a single random event (ie you and this consciousness only differ from you in the observation of a single random event) exist in another branch.
And it is not like this is all orchestrated by some entity. It is just how consciousness and subjective experiences emerges in mathematical structures (+ the set of random events), that does not need rendering anywhere (Mathematical Universe Hypothesis).
Once you understand the hopeless inevitablity of existence, a lot of questions like "When", "how", or "why" of our existence disappears.
You can ask if there is any proof for this, except for some thought experiment. But I think the only thing that can come close to proving this is if we exhaustively searched for other extra terrestrial consciousness and don't find any.
"Hard problem" makes it out to be much more difficult than it actually is. To simplify things a little bit, if you combine a spatiotemporal sense (a sense of bounded being in space and time) with a general predictive ability (the ability to freely extrapolate in time and space from one's surroundings,) "consciousness" arises necessarily. It's what having such senses feels like from the inside; the first-person view. It's a matter of degree, of course.
The writing of Chalmers and its consequences have been a catastrophe for philosophy.
It's not hard at all when you acknowledge that such senses exist in the world, and that you (like others) possess them. As an aside it tends to foster a certain tendency towards empathy.
In essence, you're asking why there's an inside to being a self-modeling system. But "inside" isn't something extraneous, something additional -- rather, it's what "self-modeling" means.
Really the "hard problem" has a very easy answer, but it's a physical/functional answer, and dualists and obscurantists simply don't like it.
It's embarrassingly silly to say but I've frequently just boiled down the hard question to the question of "where is the experience of the color blue stored in the universe?" Even as a non-dualist, I still haven't found much of an answer that I like. I'm all ears if you've got a book recommendation.
The question presupposes that "the experience of the color blue" is a discrete object that needs a storage location. But that's the dualist picture in disguise. On a functionalist view, blueness isn't stored; it's what certain neural activity constitutively is when you're that system observing that blue.
As an aside, isn't it more weird that violet and purple look indistinguishable despite being physically so different? It's said that this is because our L-cones (red-sensitive) have a secondary sensitivity peak at short wavelengths. So violet light triggers S-cones + a bit of L-cone. Purple light (red + blue) also triggers S-cones + L-cones. Similar activation pattern = same quale. It's all functional/physical.
Read Tom Cuda "Against Neural Chauvinism." Also Daniel Dennett.
> On a functionalist view, blueness isn't stored; it's what certain neural activity constitutively is when you're that system observing that blue.
Why should there be anything a certain neural activity is when making an observation? This is adding something additional to functionalism. You're just sneaking the hard problem back into the picture without realizing it.
What is mysterious to me is why and how chemical reactions in a certain part of my brain create an experience of blue.
Yes some chemical change happened there, but so what.
These are not very unusual chemical reactions. They happen and are happening everywhere. Does all the chemical reactions going on generate an experience to some experiencer?
I think the flaw in your reasoning is the assumption that chemical reaction is causing the sensation of blue.
But imagine if the consciousness and what it senses cannot be separated. So the consciousness sensing blue and the chemical reaction happening in the brain, are just correlated. One did not cause the other.
One can ask where that correlation came from. I think that the such correlations are inherent in such worlds where consciousness is possible.
I think everything that we observe as physical laws, causality etc, are just such correlations.
This is where these questions take me. Since the experience is the only thing I can be certain of, I'm less drawn to "everything is physical" answers and more drawn to ideas from phenomenology and Bishop George Berkeley. And since I'm not super religious, I'm not really comfortable with those "answers" either.
>where is the experience of the color blue stored in the universe?
It is not stored anywhere. It is part of the consciousness that experience it. In other words consciousness comes bundled with everything it will ever feel.
The kneejerk response would be: Are you not conscious at this present moment? If we were to modulate your spatiotemporal senses with drugs or a lobotomy, do you doubt that you would be very differently conscious, or perhaps entirely unconscious?
I mean, there is a credible first-person answer to that question of yours, which each man can answer for himself.
But considered more seriously, the "hard problem" is an artifact of treating experience as a separate thing that needs to be generated. If you accept that self-modeling systems bounded in space and time exist, you've already accepted that experience exists -- because experience is what such a system is, from the inside. There's no second step where experience gets added. The question "why is there experience?" is exactly akin to "Why is there an interior to four walls and a roof?" The interior isn't a separate thing; it's necessarily constitutive.
> because experience is what such a system is, from the inside.
There being an inside to self-modelling systems bound in space and time is the hard problem.
> The question "why is there experience?" is exactly akin to "Why is there an interior to four walls and a roof?" The interior isn't a separate thing; it's necessarily constitutive.
That's given from three dimensions of space. This is not the case with subjective experience. Functional and physical terms don't have an inside where experience lives. It's what makes the p-zombie argument potent.
Let's put this another way. Functional terms are abstracted from experience to model the world. See Nagel's What It's Like to Be Bat paper on science being a view from nowhere, which is really about the fundamental objective/subjective split. Or Locke's primary and secondary qualities.
You can't get experience out of abstract terms. Experience doesn't live inside abstract concepts. We can model the world with them, but experience was left out at the start.
Would you agree that you are conscious at this point?
Would you agree that there are some set of physical laws, an initial state, and a set of random events to the universe that we inhabit?
Would you agree if we simulate this initial state on a computer, and step through it using the set of physical laws, and the random events, we will see the eventual emergence "you", who we know is conscious?
So are you saying that the entity inside the simulation is a zombie who is not actually conscious?
> Would you agree that you are conscious at this point?
Of course, I'm having a conscious experience replying four days late.
> Would you agree that there are some set of physical laws, an initial state, and a set of random events to the universe that we inhabit?
We inhabit a universe modelled by laws physicists have arrived at to describe observed behavior. That's as far as I'm willing to go ontologically.
> Would you agree if we simulate this initial state on a computer, and step through it using the set of physical laws, and the random events, we will see the eventual emergence "you", who we know is conscious?
No, I don't think computation is conscious. It's abstract symbol processing.
> So are you saying that the entity inside the simulation is a zombie who is not actually conscious?
Yes, it wouldn't be me. I don't think simulating the world is the same thing as the world itself, despite all the science fiction stories to the contrary.
I'm not a dualist or anything. I'm in the "it's weird and I have no idea what the answer is" camp. And yes, I've read Dennett. I'm trying to understand your views. Lots of questions follow, but don't feel like I'm barraging you unnecessarily. Just trying to figure out your view with what seem to me like interesting questions that I myself can't really answer.
I'm using "consciousness", "subjective experiences", "senses" and "qualia" as synonyms here, but if you see a difference, please mention it. Obviously "consciousness" has many definitions that have nothing to do with the "hard problem of consciousness", so I'm using it in this sense here. I'll use "qualia" as it's the word that relates most to the hard problem of consciousness. You can substitute it with "sense"/"senses" if you like.
1. Do you view qualia as an emergent property? Of what exactly? What is a self-modeling system? Is a human one? Where would the boundaries be; would they even be defined? The human body or the brain only or the nervous system? Or whatever neurons activate when a certain thing happens, like seeing blue or feeling pain? What about animals - pigs, dogs, rats, snails, ants, bacteria? What about AI, current and theoretical?
2. Could there be a set of minimal self-modelling systems in some abstract space that are the boundary of what has qualia and what doesn't? Like, these 1000000 neurons arranged like that qualify, but if you take 1 out, they don't? Or is it a fuzzy boundary somehow?
3. What kind of statements could be made about the qualia of yourself and of others? Not sure what kind of answer I'm looking for, but how objective or truthful would those statements be? Maybe "qualia is nothing really, we only have the set of equations that govern physics and everything else is an abstraction"? Like an apple isn't anything really, it's just a badly defined set of atoms and energy. There is no "apple" or "chair". Or is it something else?
4. What are your views on meta-ethics and ethics in general? Should we care about it at all?
We have a theory whose plain reading matches experiment at all scales.
Consciousness is something else. It is tempting for humans to pair mysteries up, pyramids and aliens, or whatever. But there isn't any factual basis for linking the experience of self-awareness with quantum mechanics.
Is there a factual reason we know digital minds couldn't be conscious? Where quantum effects have been isolated from the operations of mental activity. That seems like a premature constraint to assume.
I agree. My suspicion is that token efficiency is what will drive more efficient tool calls, and tool building. And we want that. Agents should rely less on raw intelligence (ability to hold everyting in context), and more on building tools to get the job done.
Maybe the train is software that's built by SWEs (w/ or w/o AI help). Specifically built for going from A to B very fast. But not flexible, and takes a lot of effort to build and maintain.
There are cases where you would not want to reject such code, though. For example, if std::move() is called inside a template function where the type in some instantiations resolves to const T, and the intent is indeed for the value to be copied. If move may in some cases cause a compiler error, then you would need to write specializations that don't call it.
It's weird that they made a mistake of allowing this after having so many years to learn from their mistake about copies already being non-obvious (by that I mean that references and copies look identical at the call sites)
I felt this was a much better layman explanation of what a quantum computer does than simply saying a quantum computer runs all possible paths in parallel.
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