Jim Pivarski

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I have heard of versions of many-worlds that are supposed to be testable, and you're probably referring to one of them. The one that I'm most familiar with ("classic many-worlds"?) is much more of a pure interpretation, though: in that version, there is no collapse and the apparent collapse is a matter of perspective. A component of the wavefunction that I perceive as me sees the electron in the spin-down state, but in the big superposition, there's another component like me but seeing the spin-up state. I can't communicate with the other me (or "mes," plural) because we're just components of a big vector—we don't interact.

On the other hand, classic decoherence posits that the wavefunction really does collapse, just not to 100% pure states. Although there's technically a superposition of electrons and a superposition of mes, it's heavily dominated by one component. Thus, the two interpretations, classic many-worlds and classic decoherence, are different interpretations.

If the state of theory and/or experiment developed further and these asymptotic projections were shown to exist in generality, that would bolster decoherence but not eliminate many-worlds: you could still imagine a 0.0001% me being coupled with the spin-up electron. It would, however, undermine the motivation. If, instead, these asymptotic projections were shown to not exist, then that would undermine decoherence to the point of refutation (i.e. only die-hards would keep looking for variants of the theory that aren't ruled out). So classic decoherence is more falsifiable than classic many-worlds. That's what I mean by saying that many-worlds is more purely philosophical.

But I was careful to say "classic" everywhere. With this being such an active area of research, I'm sure there are versions of these theories that don't fit the description above. (They're all "more than one theory.") As I said, I've heard of variants of many-worlds that are less purely philosophical, and that must be what you're referring to, @TAG.

Most of the interpretations aren't "pure" in the sense of being completely independent of empirical constraints. Decoherence is one that posits a physical process (unlike many worlds and quantum Bayesianism) that doesn't require new laws of physics (unlike objective collapse theories, including gravity mediated). It requires a collective effect from the environment, which is why I say it's like thermodynamics.

However, it isn't as well-understood as thermodynamics. I've read some papers in which the authors describe a simple, special-case example of an environment and show that a quantum system does get pushed toward basis states like 0.001% spin-up and 99.999% spin-down. In fact, part of the problem is, "What's special about the basis states we see in the lab, like position, momentum, energy, spin up/down, field value, particle number, etc., rather than any other linear combination of them?" I remember reading about simple models in which an "isolated" particle, i.e. one surrounded by low-energy photons spontaneously coming out of the vacuum, is pushed toward its energy basis (think of a hydrogen atom, defined by its energy levels) and a colliding particle involved in one high-energy collision is pushed toward its position basis (a wave that becomes more particle-like on impact).

You're reminding me that I found decoherence more compelling than the rest. But what's missing, unless there's been a breakthrough I don't know about, is generalization. These were very simplified special cases. Also, there's still a philosophical choice to be made because this world-view is taking the collapse seriously as an objective physical process, but not a discrete one that leaves us in exact basis states. It's more like a phase transition that isn't infinitely sharp.

I doubt that anything specific to the Standard Model (high-energy generality, like electroweak symmetry breaking) has anything to do with it, since low-energy electrons also need to decohere, but you probably meant, "standard physics, no new laws," right? Decoherence is that: no new laws (unless there are yet more models of decoherence that I don't know about).

This sounds like it's using Russell's theory of descriptions, in that you're replacing "Colorless green ideas do Y" with "For all X such that X is a colorless green idea, X does Y." Not everyone agrees that this is a correct interpretation, in part because it seems that statements like "Dragons are attacking Paris" should be false.

I think it would be reasonable to say that "colorless green ideas" is not just a set of objects in which there are no existing members, but meaningless (for two reasons: "colorless" and "green" conflict, and ideas can't be colored, anyway). I think that was Chomsky's intention—not to write a false sentence, but a meaningless one.

I'm surprised that Scott Alexander's blog post didn't go for what I think is a more obvious connection between conservatism and conservationism: religious fundamentalism.

The way man acts these days... [shakes head, downcast] forswears a God-given charge to protect this God-given Earth. The way he chokes the air with smokestacks, plunders the oceans of her fishes, and paves the green hills flat with concrete—it sickens me. Gets me [thumps chest with mic] right through the heart. His vainglorious pride to try to change the natural order of things, the intricate tapestry of birds and deer, trees, antelopes, and groundhogs, from the mighty whale down to the humblest anthill—modern man thinks he knows better how to till the Earth. What does he till it with? Monoagriculture and pesticides! And what does he reap? Monoxides and pestilence! [Swell of the organ, roar of the audience]

I see a grave judgement coming! I see the cry of the Earth, rising up to the heavens, carried on winds of carbon dioxide, of nitrous oxide, the methanes and the synthetic fluorinated gases—all!—rise up to the heavens! And they cry out to the Lord, "My God, how long?" [long pause] And the Lord answers. "Not long. No, not long now." For there is a judgement coming. Indeed, the stench of our industrial civilization is both sin and the wages of sin. Silently sealing us off from the heavens, to bake in the stew of our own filth. As in the days of Noah, the waters will rise.

Oh Lord, save us from this mighty cataclysm! Make us turn in our hearts from the plastics and the petroleums of our idolatry to the wholesome fruits of your loving kingdom. Yes! We long to return to the fields and meadows of your abundance, Lord. Help us break our addiction to the spoils of modern life that poison your garden. Give us moral strength to abstain from consumer culture, from gas-guzzling SUVs, from industrial meat production, from coveting a bigger house, a bigger yard, fast fashion, and the latest i-Phone! Yes! Save us from the harlots of modern convenience, and return us, Lord, return us to the bosom... of your care.

This is both interesting and (I think) an important thing to know about science: plans and strategies are systematic, but discoveries sometimes are and sometimes aren't. In particle physics, the Omega baryon and Higgs boson were discovered in deliberate hunts, but the muon and J/psi were serendipitous. The ratio might be about half-and-half (depending on how you count particles).

Thinking about this, I have two half-answers, which may be leads as to why sweetener discovery might be discovered by serendipity, even though there are systematic searches for new drugs.

  1. Discovery depends, to a great degree, on your detector, and I don't think there's a better detector of sweetness than the ones in our mouths. Presumably, searches through virtual (not synthesized) molecules can be faster, and if the identification algorithm can accurately predict activation of the sweetness receptor, then it could outperform detection by taste only because it's faster than synthesis. But virtual drug discovery is still an open problem, still under development...
  2. Maybe there are, in nature, only a few sweet molecules, and they were discovered early. Going through the list of artificial sweeteners you mentioned, below are the discovery dates. When were most of the systematic drug searches? Did it cover this timespan, which seems to be in the early and mid-20th century?
    1. Saccharin: 1897
    2. Cyclamate: 1937
    3. Aspartame: 1965
    4. Acesulfame potassium: 1967
    5. Sucralose: 1976

(This suggestion also has an analogy with particle physics: hundreds of particles were discovered in the 1950's because accelerators had just been invented that could illuminate the strong-force mass range, which has rich phenomenology. At the current frontier, though, there are very few particles.)

Other comments in the comments section that sound quite likely to me are: (1) perhaps the very sweet compounds could be smelled, which prompted chemists to try tasting them (@mako-yass), and (2) maybe some of these origin stories are scientific folklore (@d0themath). Scientists, who are very concerned to get the description of physical reality right, are surprisingly cavalier about describing their own history in an accurate way.

This story from the perspective of the Thing did get into the notion of what it would be like to be an amorphous consciousness (and how odd it is that Earthlings aren't). It's still a little different, though, from the trajectory of being human and then realizing what it's like to be multi-human. A version with Pod People would be a different kind of story...

Cool! I'll read that one, too, thanks!

What I was thinking about with the pod people was their group mentality. (After all, it has long been considered a metaphor for communism.) I'd like to see someone imagine—or do it myself—the poddified people not as soulless outer shells of their former selves, but as themselves, "melted" into a group consciousness. As an example of something similar, the Buffy the Vampire Slayer episode, "The Wish" did an excellent job showing characters who remained themselves, but as evil versions of themselves, as vampires.

In the Invasion of the Body Snatchers and its remakes, the reason the poddified people are hard to distinguish from their former selves is because they're good at mimicry. They were only pretending to be their former selves. However, if one person's consciousness really isn't distinct from another's in a fundamental way, just by a much thinner channel of communication than that between the parts of one's brain, then thickening the channel of communication between people by telepathy would probably feel like a kind of awakening—realizing that there are all these other parts of you that had been hidden until now. These people would probably talk and act as they did in the Body Snatcher movies: they'd tell the anti-pod antagonists that there's nothing to fear from poddification, that they haven't lost anything, they've only gained a wider consciousness, etc., while the antagonists recoil in horror because it's a threat to their individuality. Whenever someone is poddified, they change their mind not because they've been overcome, but because now they, too, see what they've been missing.

Personally, I can't say which side I'd be on. It would be underwhelming for the author of this remake to just reverse the moral (individualism is bad; all is one, baby!). It is horrific to think of one's personality melting into a larger brain. Also, the end-state of that is sopolistic: there would be only one consciousness, with no one to talk to. (But then again, wanting to talk to others is wanting to thicken the connections between bits of consciousness, so that's the same thing again.)

Although G.K. Chesterton wildly misunderstood other cultures and was triumphalist about his own, I've always rather liked this image from The Romance of Orthodoxy (1908):

The oriental deity is like a giant who should have lost his leg or hand and be always seeking to find it; but the Christian power is like some giant who in a strange generosity should cut off his right hand, so that it might of its own accord shake hands with him.

What this "nuclear consciousness" mental model doesn't have is an account of knowing someone without being that someone. But then, is there such a thing?

That's why I'd like to see a rewrite of the Body Snatchers: to explore that idea, even if it doesn't come to a solid conclusion.

But if that observer is in the universe, then there's more in the universe than just the circle.

I was examining this universe from the outside. We can't actually do that, though we act as though we do in the physical sciences. (One idea in the physical sciences that takes seriously the fact that experimenters are a part of the universe they observe is superdeterminism, and it's one of the possible loopholes for Bell's Inequality.)

Panpsychism! (Sort of!) But I guess that makes sense, since panpsychism is trying to make sense of divisibility of consciousness, too.

I will read it, thanks!

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