How much better are physical possibilities than logical ones?

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Gadianton
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How much better are physical possibilities than logical ones?

Post by Gadianton »

A while back we discussed Sean Carroll's criticisms of Chalmers and it's hard not to be sympathetic. But if we want to stick with real - reality, rock solid physics, how much clearer does the world look?

For a low price, I can get an app for my phone endorsed by Sean Carroll that puts a photon in superposition and thus, splits the universe. The more I use the app, the more I flirt with bringing universes into reality where Hitler is resurrected and rises again or terrible natural disasters kill millions of people. The app is rated age 4 +. Quite a lot of responsibility for a kid.

There's got to be a misunderstanding, right? Many Worlds is about interpreting measurements and we don't need to attach all this baggage but nonetheless, the baggage gets attached, and it's not coming from non-physicists straying from their lanes.

some guy has done a good job culling good examples from physicists. It's a bit long, and I started losing him about 2/3's of the way through, but I t:

(taken from an interview)

Harris: But it’s still happening. So there was some [“minute”?] possibility that I might have picked this up and put it down and then picked up again and put it down and did that 75 times…

Carroll: Yep.

Harris: …to the consternation of everyone in the room.

Carroll: Hopefully the probability is low, but yes.

Harris: But if there’s a non-zero possibility of that, that happened somewhere. Right?

Carroll: Yes, that’s right.

-------
There were stories about him (Yakir Aharonov) when he used to be at Yeshiva University in New York, where he would walk into people’s offices in the philosophy department just in order to have something to do that evening, and say, “Describe a physical effect which is obviously impossible.” So people would say, “I don’t know, a man turns into an elephant,” or something, and Aharonov would go home and figure out a quantum mechanical way that this could happen. And this was the kind of exercise that lay behind many things that he discovered.
-------
Tegmark: [brief chuckle] Exactly. Or I switch to talking French. … [skipping ahead about two minutes] … So if you have an infinite number of other regions equally big, and you roll the dice again in all of them, then you can calculate that if you go about a googolplex meters away, you will indeed end up with just what you described: a universe that’s extremely similar to this one except that one minute ago you all of a sudden decided to start speaking Hungarian instead.
Dan wrote: Maybe Tegmark knows French. Or maybe he meant that he would suddenly start speaking French despite not knowing that language. This is the more interesting option and the one I’ll assume he means us to imagine, particularly given the second bewildering scenario Tegmark asks us to imagine for Harris, who I’ll safely assume does not know Hungarian: “one minute ago you all of a sudden decided to start speaking Hungarian.”

Here we are now, as far as I’m concerned, well into a world of “worse.”

What I consider the worse are possibilities involving the spontaneous rearrangement of the parts composing a well-functioning human brain—often noted to be the most complex bit of machinery in the known universe—into some new, equally well-functioning human brain, but one of an entirely different character.
I have to say this is the perfect explanation for any anomaly. If we can expect people to randomly speak Hungarian, then I don't see why we can't expect a being named Moroni to visit Joseph Smith. In fact, in some world out there, Joseph Smith is a prophet at Mormonism is true. Why not this world? I could wonder: whatever happens, couldn't it be true that what would seem as fanciful would somehow not be so fanciful within the world on instantiation? But then, I have to admit that in some worlds, such events would wind up as being viewed as confounding anomalies by the inhabitants while in other worlds, all would seem normal.
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Re: How much better are physical possibilities than logical ones?

Post by Physics Guy »

The Many Worlds interpretation of quantum mechanics postulates an unimaginably uncountable infinity of unobservable other universes. It has to be the most spectacular violation of Ockham's Razor ever suggested. It postulates all these unnecessary entities in order to avoid having to postulate a special rule for quantum measurement: it takes on infinitely many whole additional universes, which no-one will ever be able to see, in order to eliminate one axiom. That would be far too high a price to count as parsimony even if it succeeded in eliminating the axiom. I don't think it does.

I don't think it does, because if you don't have a measurement postulate, then the rest of quantum mechanics keeps on giving you plusses: spin-up plus spin-down, click-left plus click-right, live-cat plus dead-cat. Fine, it's simple algebra, vectors add. But our experimental colleagues are going into the lab right now to measure that state. They're asking for our prediction of what they will see.

If we want to be right, we have to tell them "or" instead of "plus". They won't see a cat that is somehow both alive and dead. They'll either see a live cat, or a dead one. That's not just naïve intuition: that is quantum measurement. You see "or".

If you formalise your formulation of quantum mechanics then you are stuck with the basic problem that the theory needs its plusses—that's weird but well established—and yet experiment needs its ors. So you need a logical rule that lets you turn a plus into an or, under appropriate circumstances. The traditional measurement postulate of quantum mechanics supplies that rule. If Many Worlds also does, then it doesn't really eliminate an axiom, but just dresses it up in different-sounding words. If Many Worlds doesn't have a rule for changing plusses to ors, then it can't give correct predictions for experiments.

That's the logical problem I see with Many Worlds, that it doesn't remove an axiom but only slips it past with fast talk. There's also a serious problem of premature judgement.

The good old measurement postulate is unsatisfactory because it's vague and opaque. It's like an Aristotelian theory of gravity, saying that things fall because it is their nature to fall. It does seem to be true, but there has to be more to the story than that. There's lots of room to discover the longer story, though, by understanding more about irreversible amplification, before we are going to be forced to look at parallel universes.

Quantum measurement is only simple in theory. The devices and processes that do it, that amplify atomic-scale phenomena into things we can see, are extremely complicated. How these gadgets work is understood well enough to build and use them, but our cave-dwelling ancestors were also able to build and use sharpened rocks without understanding the structure of matter. We only understand photomultipliers and cloud chambers and the like on a crude level, not on the microscopic level of the phenomena that we use them to see. We can learn to understand these things better. If we push nanotechnology far enough, we'll likely run into them, anyway.

So insisting that we need to accept Many Worlds in order to make sense of quantum measurement is like declaring that the murderer must have teleported away, when there's a trail of bloody footprints running into the woods.
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Re: How much better are physical possibilities than logical ones?

Post by DrStakhanovite »

Excellent post Dean.

I have very little to add except to say I’ve always appreciated a certain insight I got from Karl Popper. When you have an expansive system of thought, inexplicable events can be easily explained with “just-so” stories, ad-hoc explanations that sound eminently plausible from within the system, but not from the outside. Popper was complaining about the Marxists and Freudians in Vienna at the time, but I think it can apply to just about any metaphysical worldview as well.
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Re: How much better are physical possibilities than logical ones?

Post by Gadianton »

I was hoping for a vigorous defense of anomalies but I'll take the additional core education.

How often are "measurement" events going on outside of humans doing experiments?

Is it like, for every experiment where a photon is brought about in a lab, the same equivalent thing is happening a trillion time over in nature anyway?
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Re: How much better are physical possibilities than logical ones?

Post by High Spy »

Gadianton wrote:
Wed Jul 06, 2022 4:48 am
I was hoping for a vigorous defense of anomalies but I'll take the additional core education.

How often are "measurement" events going on outside of humans doing experiments?

Is it like, for every experiment where a photon is brought about in a lab, the same equivalent thing is happening a trillion time over in nature anyway?
There are two timing pattern anomalies at march8miracle.org that may culminate July 2023.
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Re: How much better are physical possibilities than logical ones?

Post by Physics Guy »

How often measurements happen naturally is a very good question, to which I don't have a great answer.

Everybody I know assumes that whatever measurement is, it doesn't have anything particular to do with consciousness. The paradox (if that's what it is) of Schrödinger's Cat was long ago supplemented by "Wigner's Friend", in which we seal off the lab in which the Cat experiment is being conducted, and then wait a while before opening the door to ask the people inside how the cat is doing. Is the whole lab in a superposition state until someone outside measures it?

The moral usually drawn from this meta-thought-experiment, with its obvious threat of infinite regress until the criterion of objective reality becomes Twitter, is that it's not about what we knew or when we knew it, but about what we could have known, whether or not we tried to find out. Irreversibly amplifying a microscopic signal into a durable macroscopic record should count as a measurement, regardless of whether any conscious being happens to notice the record.

We don't actually understand very clearly what "irreversible" and "macroscopic" mean, but at least we're less confused about them than we are about consciousness. In principle a quantum measurement could surely be conducted by some non-sentient or even inanimate natural process.

The question is how often that will actually happen. I haven't thought about this myself before, nor do I remember hearing anyone else's thoughts about it. My initial guess, though, is that quantum measurements are probably pretty darn rare except in artificial labs. Detectors with the necessary sensitivity are pretty tricky to make, even with conscious intelligence and technology. Nature does realize some technological processes, albeit in pretty different ways from our own ways. There are natural masers and maybe even lasers, operating in gas clouds in space. Stars are fusion reactors. There probably aren't naturally occurring computers, however. My guess would be that quantum detectors are more in the computer category, though not as absurdly unlikely as computers, as natural phenomena.

One big reason for that guess is that quantum detectors are all quite unstable. That's how they work: they're primed to undergo big and lasting changes as hair-trigger responses to tiny disturbances. They're like a house of cards, or a bunch of pencils balanced on their points. Besides just being ready to collapse at the slightest bump, though, they are also ready to collapse in lastingly different ways depending on exactly how they get bumped—like a house of cards that is somehow rigged to fall with all the red cards facing up if it gets bumped from the left, but with all the black cards facing up if it gets bumped from the right. So after it falls you can easily read out at least some information about how it got bumped, not just see that it got bumped. It just seems to be asking a lot, of a natural system, for it to create and protect this kind of multiply unstable state long enough for it to function as a quantum detector.

Furthermore, for the red-versus-black house of cards to be a good detector of bump direction, you need to be sure that it will land red-up if and only if it got bumped from the left, and black-up if and only if it got bumped from the right. If in fact there are a lot of different factors that could make it land either way, then you don't really learn anything specific from seeing that it has collapsed red-up or black-up. In a situation like that, even if what actually hit the house of cards was a quantum superposition of a left-bump and a right-bump, you really wouldn't be able to infer that, at all, from the measurement, because lots of other possibilities would remain open, as far as you can tell in hindsight.

Quantum measurement really only counts as quantum measurement if your measurement can show evidence of qualitatively quantum behaviour. Quantum fluctuations in themselves don't look any different from mundane noise, except in their statistical properties. There is no way to tell the difference, in an experiment, between a persistent noise in the data that is due to quantum vacuum fluctuations and a noise that is due to a mouse gnawing a cable under the lab bench—if the mouse happens to gnaw in accordance with the Planck distribution. So in practice you decide that you have cooled your system to the ground state when the noise fits the quantum theory for that; as long as it doesn't fit, you assume you still have work to do in cleaning your electrodes to get rid of patch charges, and sealing air leaks, and stuff. Maybe look for a mouse.

So for a natural quantum measurement we'd need an unstable system poised between multiple stable alternative states, which is hair-trigger sensitive to a specific small set of possible disturbances, and highly insulated from all other kinds of disturbance. This sounds really unlikely.

A very interesting question, though, which I may even try to incorporate in my next quantum course.
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Re: How much better are physical possibilities than logical ones?

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Gadianton wrote:
Sun Jul 03, 2022 6:37 pm
A while back we discussed Sean Carroll's criticisms of Chalmers and it's hard not to be sympathetic. But if we want to stick with real - reality, rock solid physics, how much clearer does the world look?

For a low price, I can get an app for my phone endorsed by Sean Carroll that puts a photon in superposition and thus, splits the universe. The more I use the app, the more I flirt with bringing universes into reality where Hitler is resurrected and rises again or terrible natural disasters kill millions of people. The app is rated age 4 +. Quite a lot of responsibility for a kid.

There's got to be a misunderstanding, right? Many Worlds is about interpreting measurements and we don't need to attach all this baggage but nonetheless, the baggage gets attached, and it's not coming from non-physicists straying from their lanes.

some guy has done a good job culling good examples from physicists. It's a bit long, and I started losing him about 2/3's of the way through, but I t:

(taken from an interview)

Harris: But it’s still happening. So there was some [“minute”?] possibility that I might have picked this up and put it down and then picked up again and put it down and did that 75 times…

Carroll: Yep.

Harris: …to the consternation of everyone in the room.

Carroll: Hopefully the probability is low, but yes.

Harris: But if there’s a non-zero possibility of that, that happened somewhere. Right?

Carroll: Yes, that’s right.

-------
There were stories about him (Yakir Aharonov) when he used to be at Yeshiva University in New York, where he would walk into people’s offices in the philosophy department just in order to have something to do that evening, and say, “Describe a physical effect which is obviously impossible.” So people would say, “I don’t know, a man turns into an elephant,” or something, and Aharonov would go home and figure out a quantum mechanical way that this could happen. And this was the kind of exercise that lay behind many things that he discovered.
-------
Tegmark: [brief chuckle] Exactly. Or I switch to talking French. … [skipping ahead about two minutes] … So if you have an infinite number of other regions equally big, and you roll the dice again in all of them, then you can calculate that if you go about a googolplex meters away, you will indeed end up with just what you described: a universe that’s extremely similar to this one except that one minute ago you all of a sudden decided to start speaking Hungarian instead.
Dan wrote: Maybe Tegmark knows French. Or maybe he meant that he would suddenly start speaking French despite not knowing that language. This is the more interesting option and the one I’ll assume he means us to imagine, particularly given the second bewildering scenario Tegmark asks us to imagine for Harris, who I’ll safely assume does not know Hungarian: “one minute ago you all of a sudden decided to start speaking Hungarian.”

Here we are now, as far as I’m concerned, well into a world of “worse.”

What I consider the worse are possibilities involving the spontaneous rearrangement of the parts composing a well-functioning human brain—often noted to be the most complex bit of machinery in the known universe—into some new, equally well-functioning human brain, but one of an entirely different character.
I have to say this is the perfect explanation for any anomaly. If we can expect people to randomly speak Hungarian, then I don't see why we can't expect a being named Moroni to visit Joseph Smith. In fact, in some world out there, Joseph Smith is a prophet at Mormonism is true. Why not this world? I could wonder: whatever happens, couldn't it be true that what would seem as fanciful would somehow not be so fanciful within the world on instantiation? But then, I have to admit that in some worlds, such events would wind up as being viewed as confounding anomalies by the inhabitants while in other worlds, all would seem normal.
How do we make the move to every imagined myth happened somewhere on a many worlds view? I'm not seeing how many worlds would entail this. There's a slim possibility there's a God therefore there's a God in some world but not his one or another one because there's also a possibility there's no God? I'm struggling to see how our imagining something into existence puts something into existence. While there's a possibility Harris did whatever it was 75 times we can say it happened in some world, I don't see that as saying the same thing as there really is a world conceived of by L Ron Hubbard. If we don't have spirits inside us, how is it possible to say we would in another world?
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Re: How much better are physical possibilities than logical ones?

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I never quite got that, either, about Many Worlds. I'm not sure that MW even really involves assuming that everything which is possible is actual somewhere.

That's not necessary for quantum mechanics, which in its normal (and well-tested) formulation does say that at any one time the universe is in one specific state. If you ask whether the universe is in that exact state then the answer is an unambiguous Yes. If you ask whether the universe is in any state orthogonal to that state then the answer is an equally definite No. It's only if you ask whether the universe is in some state that has some commonality with that state, despite not being identical to it, that you get "maybe" answers with probabilities.

That's all possible because different possibilities in quantum mechanics are never just mutually exclusive; there's a range of shades of gray between every possible black and white. So for example three states that are really completely different, with no common features, would be like three lines running along perpendicular directions: North-South, East-West, or Up-Down. If you're in the North-South state then you're definitely not East-West or Up-Down. But you could be Northeast-Southwest. In that case you're definitely not Up-Down, but you're a 50-50 maybe to be either North-South or East-West. Or you could be North-northeast-South-southwest, in which case you're more North-South than East-West, but you do have a bit of East-West in you.

So for any given quantum state there are a whole bunch of somewhat different states that are also potentially true, in some sense, in that they have some overlap with the exact state. But there are a lot more (really a lot more) states that have zero overlap with the exact state; whatever these states represent are things that definitely do not happen at all.

It's not that everything does happen just because it could happen. Some possibly contradictory things could all potentially be happening, but most things really do not happen, period, even in quantum mechanics.

The other thing about Many Worlds is that even if it says that all these inconsistent alternative possibilities are in fact really happening in parallel "worlds", then there is still the question which is important to me, "What determines which world I am in?" To me this question seems in practice to be identical to the good old question of, "What really happens?" It's just that Many Worlds people are allergic to those good old words, and want us all to use their new philosophically correct words about which world we seem to inhabit, or something. I'm not impressed by any supposedly new formulation of a theory that really only boils down to word substitution.
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Re: How much better are physical possibilities than logical ones?

Post by Marcus »

Physics Guy wrote:
Wed Jul 06, 2022 7:43 pm
...So for any given quantum state there are a whole bunch of somewhat different states that are also potentially true, in some sense, in that they have some overlap with the exact state. But there are a lot more (really a lot more) states that have zero overlap with the exact state; whatever these states represent are things that definitely do not happen at all.

It's not that everything does happen just because it could happen. Some possibly contradictory things could all potentially be happening, but most things really do not happen, period, even in quantum mechanics...
okay, i'm calling it. Sheldon has taken Physics Guy's class:
Penny: Morning, Sheldon. Come dance with me.

Sheldon: No.

Penny: Why not?

Sheldon: Penny, while I subscribe to the many worlds theory which posits the existence of an infinite number of Sheldons in an infinite number of universes, I assure you that in none of them am I dancing.

Penny: Are you fun in any of them?

Sheldon: The math would suggest that in a few I’m a clown made of candy. But I don’t dance.


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Re: How much better are physical possibilities than logical ones?

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As a fictional character, Sheldon exists outside time, so his endorsement of my views must carry exceptional weight and I am grateful for it.
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