As intriguing as complex representations in physics, for me, is how linear operators are so effective. One would think nature to be complicated and non-linear; linearity is a very stringent condition, while simplifying the math. However, it is a seasoned trick in the profession to approximate the non-linear by linear constructs, and, of course, ordinary differentiation and integration are linear operators. — jgill

Yes, perturbation theory being an obvious example. Quantum electrodynamics is usually treated with perturbation theory, with each term in the perturbation series being a Feynman diagram.

Biologists do believe adaptation is the most important factor in bacterial evolution, but not for humans. — frank

I think you're confusing biologists and creationists. You're a religious man, I take it.

Here's an article about what British scientists think of him. — frank

Thank you for, after being asked about six times, finally citing something vaguely related to your original assertion. It's a shame that the study in question says nothing about Dawkins' scientific publications (what you call "junk science"). It's a bigger shame that the study was by the Templeton foundation, which gives us a lot of information about the people who agreed to be a part of it (few scientists would agree to help the Templeton foundation, though Dawkins himself gave an anti-creationist talk there).

No, its the view that all characteristics of a population must be products of adaptation. — frank

No, it isn't, that's pan-adaptationism. Dawkins is not a pan-adaptationist. Like Myers, Dawkins also believes that genetic drift is a factor in evolution. He just knows that adaptation is the more important, as per evolutionary biology consensus, while Myers appears to be a joyfully paranoid crackpot who knows very well he is far outside the mainstream in believing that genetic drift gave birds wings.

I dont want to explode your logic centers, but... — frank

Well, you sort of have. My mind is blown that you think one person outside the mainstream of evolutionary biology somehow represents the entire consensus. My mind is similarly blown that, no matter how often you're called out on that dishonesty, you gaily plough on with it as if it were effective.

You don't appear to understand what an adaptationist is. — frank

It's the view that many characteristics are evolved to fit the organism's environment.

You gonna cite that source or stop bullshitting any time soon?

I did. The Myers video goes into detail about why adaptationism is bad science. Did you want a citation that proves Dawkins is an adaptationist?

Uh. — frank

I even reposted the question, you cannot be this thick. Was the question: "Can I have a reference for the claim that Myers is an anti-adaptationist?"Again, your claim was about the evolutionary biologist consensus. Do you have a reference for this or did you just make it up? One person does not constitute a consensus.

By the way, Myers is also an adaptationist. You helpfully posted a video at the start of which he says adaptation is definitely real. :up: :100: :cheer:

But it is explained, quite thoroughly, in genetic theory. Of course, genetic theory has assumptions, all theories have. They're far from "unexamined" though. — Kenosha Kid

It's worth going into this a bit more. Midgley is a Darwinist, so accepts that characteristics which benefit the individual are more likely to be inherited by the next generation. If she does not accept at least this degree of "selfishness", she's confused about what she believes. In genetic theory, biological characteristics are coded for by genes, therefore sequences of genes that yield characteristics beneficial for survival will be passed on to the next generation, thus perpetuating the genes. This is the "selfishness" of genes: a metaphor for how survival characteristics of individuals act as media for the longevity of the genes that encode them.

There is nothing truly social about this metaphorical "selfishness", and Midgely's beef that Dawkins presents human altruism as arising from elementary social selfishness is dim. The fact that she knows this and does it anyway all the more so. The more I read, the more she strikes me as being quite happy to knowingly misrepresent her subject for the sake of tubthumping.

But on the contrary, the selfishness of things without selves is taken as - what shall we say? - part of the natural order, and in need of no explanation but the explanation of everything else. — unenlightened

But it is explained, quite thoroughly, in genetic theory. Of course, genetic theory has assumptions, all theories have. They're far from "unexamined" though.

Stop being so belligerent and learn something. — frank

I've specifically asked you to teach me about your particular claim. You seem very intent on avoiding that. Is there a magic combination of words? Pretty please with a cherry on top? No? Well, if you can't...

This is the same equivocation I was complaining of in Dawkins. If its built into something, it cannot be a metaphor. the scare quotes prevent me from taking it seriously, but the continuation of the sentence does exactly that. — unenlightened

The thing that the metaphor is a metaphor for is what is built in. It sounds like you're saying that unless the metaphor is continuously restated, it somehow ceases to be a metaphor.

Haha! Midget! Politically autoincorrect...

It's clear her target is the supposed science being popularised as well as the populariser himself. — unenlightened

She does seem to have it in for genetics generally.

and the unexamined assumption is that selfishness requires no explanation because it is metaphorically literally built into the genes. — unenlightened

I don't think that's the unexamined assumption she's talking about. Dawkins was not a social Darwinist and The Selfish Gene doesn't push a social Darwinist agenda, although she seems to mistake him for one. The entire article seems like a substitution fallacy, based presumably on reading very little of the book she was criticising. Dawkins himself has frequently marvelled that we are as altruistic as we are.

The "selfishness" of the gene isn't built into the gene, but into also the environment, the selection laws that stem from them, and the process of hereditary reproduction. Midget claimed to be a Darwinist, so I don't think she can rationally take issue with heredity or reproduction. She does seem to have it in for gene theory though.

Are you just going to continue to pretend you said something else? I'll remind you of your words and my question:

Evolutionary biologists agree Dawkins is junk science.
— frank

Reference? — Kenosha Kid

There seems to be a somewhat pervasive misunderstanding, Dawkins hasn't really contributed much to the primary literature, his Selfish Gene book was basically a popularized synthesized compilation of the work of influential evolutionary biologists: Williams, Hamilton, Trivers, etc. No one thinks those figures contributed junk science, but it's just an extremely narrow perspective if you leave it at them. — Saphsin

Madgley makes basically the same point, which is odd. The Selfish Gene is a popular science book aimed at bringing scientific knowledge to the lay masses. It seems odd that Madgley's first criticism of the book is that it didn't publish and new findings, as if she's not aware of the difference between pop sci and a journal.

Find a lecture by PZ Myers. Dawkins is an adaptationist. That's basically Nazi science. — frank

Haha! Straight to dubious Nazi accusations, like it!

That's not an answer to the question as I'm sure you're aware. Can you support your original assertion or not? Just curious, it doesn't matter much.

But in fairness to Mary, he forgets that completely in the body of the book and takes himself literally. — unenlightened

Such as? I haven't read it in years, but don't recall it being presented as anything other than a shorthand.

What's Lost? — Banno

I envy you. Lost was a TV series about 20 years ago that was incredibly dumb with intellectual pretensions.

Evolutionary biologists agree Dawkins is junk science. — frank

Reference?

Finish the first paragraph, where she talks about his use of Metaphor, and get back to us. — Banno

This feels like Lost all over again: all evidence suggests it's crap, but I'm being assured that if I keep going it gets better.

Anyway, read it. So she's doesn't understand metaphor even when it's explained to her.

Here's the core of her rebuttal of The Selfish Gene:

Genes cannot be selfish or unselfish, any more than atoms can be jealous,
elephants abstract or biscuits teleological.

Glorious! — Banno

So she doesn't understand metaphor. Is that good?

Well, if complex numbers are nothing more than a mode of computation, there's no reason to worry about their use in the wave function. — Olivier5

Thanks, I'll try not to lose sleep over it.

If complex numbers fit the bill better than real numbers to describe a particular phenomenon, maybe it means something... — Olivier5

It does mean something. It means that complex exponentials are easier to do calculus with than sine waves.

Note that electric impedance is a complex variable. So there exist classic physical variables described by complex numbers. — Olivier5

That is also merely a convenient representation. Voltage and current are real, but in AC currents they are sinusoidal. Complex exponentials are easier to manipulate mathematically than sinusoidal functions, and one can simply dismiss either the real or the imaginary part at the end. Impedance is then the ratio of the complex voltage to the complex current. This does not mean that the voltage or the current are truly complex; it is merely convenient to treat them thus.

I'll give you a few examples of why the complex wavefunction might be complex because of representation-specific factors, which I think will answer your question.

1. The wavefunction contains unphysical information

The wavefunction doesn't just encode the dynamics of the particle, but of similar particles in similar scenarios. The actual particle is described entirely by real quantities, but we cannot know them and the minimal representation that covers them all is complex. This is the case in Bohmian mechanics and can be taken as an extreme case of the OP in which only real trajectories are ever tried.

In which case the best, minimal representation of the particle is not an isomorphism of the complex wavefunciton, avoiding the problem you see,

2. The wavefunction contains physics not about the particle

This is where I'd hedge my bets the most, which is essentially that, due to our choices about how to represent particles, the minimal quantity we can deal with has to be complex in order to yield good experimental predictions. In this case, the truest minimal representation of the particle (i.e. in a better representational framework) would again not be isomorphic with the complex wavefunction.

This is the case with special relativity, where to get the right answers out in simpler representational frameworks, some of the four-vector elements have to be complex. This is avoided by a more sophisticated framework involving metrics, which is not typically done in QM except in attempts to do QM in curved spacetime (as far as I am aware).

3. The wavefunction contains only information about the particle but in a suboptimal representation

Here we might not gain or lose information about the particle as we hop from one representation to another, and in fact the relationship might be isomorphic. However, in our choice of representation, that information must be encoded as a complex field. This is, I think, the one you have in mind.

An example might be that space is 4D, containing an additional compactified dimension, and that the true meaning of the complex phase is a coordinate along this angle. So what we represent as $\psi(\mathbf{x}) = f(\mathbf{x})e^{iA(\mathbf{x})}$ (such that $n = f^2$) might better be something like $\psi(\mathbf{x}, \theta) = f(\mathbf{x}) cos(\theta)$, which yields all of the desired interference effects.

This is an isomorphism to and from the complex wavefunction and would be physically meaningful. However the complexity of the wavefunction would then simply be a non-physical artefact of an incorrect choice of representation, i.e. a representation that does not correspond to the physical universe. Of course, we could only say that if there was some test for it. Maybe some future test is possible, but for the time being the wavefunction is not an observable, and, were it observable, QM says we would not observe it as having a complex value*, which is sufficient (I think) to state that it is non-physical as represented.

*The condition of real numbers for observable quantities is a postulate of quantum mechanics, manifest as the insistence on Hermitian matrices to represent physical operators. This is all I really had in mind when I referred to the complex wavefunction as nonphysical, i.e. the minimalist thing we can do with the wavefunction is to act on it with the Hermitian density operator. That said, I think I'll defend the broader point you're taking me to task on.

That would be dandy, except that "magic" is a very vague term, often applied to things we don't quite understand but seem nevertheless real. The magic of the gap. And this is the case here: Pfhorest's use of the word 'magic' only denotes that he doesn't understand something, and thus rejects it as impossible. — Olivier5

And yet it looks exactly like you don't understand and he does. Weird how these things go.

Somehow individual measurements are physical but tabulating them makes them incapable of being physical. — fdrake

How you tabulate results is a matter of convention, for communication, or performance. You can represent classical waves as sine waves: completely real. Or, for ease, you can represent them as complex waves. For the exact same wave. The latter adds information that is related to the former (because imaginary sines are related to real cosines and vice versa), but we're not transforming the physical wave from a real field to a complex field. It's still real. So how we tabulate things can't change their physical reality.

Nature can "know" about the vector elements but not the vector — fdrake

Yes. Vectors are a way of dealing with multiple similar quantities which transform in similar ways. Some of those quantities may be related to one another, but there's nothing I can think of that makes the interpretation of the vector as anything more than a notational convenience.

EG: if the criterion for a theory (as a whole) being physical is successful prediction of experimental results ("manifesting as real"), it's silent on theory elements... — fdrake

Beyond falsification, which depends on the element and how it works inside the theory, yes.

I won't quote the rest, just sum up. A theory is tested empirically, not it's individual elements. If the theory as a whole (or a subset of elements, catering for irrelevancies to a particular experiment) yields otherwise inexplicable or more accurate predictions for experimental outcomes, it's a good theory.

What we see in QM is that it's a good theory, but contains various combinations of elements to which experimental outcomes are insensitive. It might be that you cannot remove or replace or augment just one element, but the whole combination.

This is evident in the various interpretations of QM. in Copenhagen, the electron is a complex wave, the field acts linearly, there is one measurement outcome and spontaneous collapse. In MWI, the electron is a complex wave, the field acts linearly, there are an infinity of outcomes and the wave evolves forward in time deterministically. In Bohm, the electron is a real, classical particle, the field is nonlinear, there is one outcome, and the particle evolves forward in time deterministically. In transactional QM without my edits, the electron is a complex wave, the field is linear, there is one outcome, the wave evolves forward and backward in time but probabilistically.

They're not all right, yet they all, in principle, yield the same predictions of the same experimental outcomes. Nature cannot care that much how we represent it.

Strong emergence definitionally differs from weak emergence. Things that meet the criteria for strong emergence are “like magic”; things that only meet the criteria for weak emergence are not. So things that are not “like magic” — not of the same character as the things compared to magic — are not meeting the criteria for strong emergence.

@Kenosha Kid, please back me up here. — Pfhorrest

Yep! The examples I gave earlier are where emergent properties of a system are modes of interaction that are inaccessible to individual components, but still qualitatively the same thing. Like solidity from certain atomic structures but is nonetheless just modes of electrostatic interaction, itself manifest in atoms.

Strong emergence describes new qualitative properties that are present in a system that are not present at all in its components, not just new modes but a new kind of thing. An example is consciousness as described by dualists who dip a toe in materialism but don't commit. Their idea of consciousness is not modes of neurological behaviour, but an entirely new thing that emerges when atoms are configured into brains. There's no explanation for it, no evidence to support it, it makes no logical sense, but it is essential to them because they need the universe to be anthropocentric: we cannot be an accident.

, since you see no difference between weak and strong emergence, the two things are one and Pfhorrest and I call this 'weak emergence'. Since you see no emergence as being like magic, weak emergence is non-magic. Magic emergence isn't real, obviously, so if anyone proposes a new kind of emergence that is magic, you know this isn't real. Pfhorrest and I call this nonexistent magic emergence 'strong emergence'. It doesn't matter what it is, because it doesn't exist.

It seems to be that time of month again which we are inundated with religious threads by new posters. They will be collected here, and this post will serve as an index. — StreetlightX

Oh good. At last check, 7 out of the first 12 threads were Christian stuff. It's like a crusade or something.

If it's impossible for an imaginary quantity to be physical, and it's possible for a real quantity to be physical, why would it be the case that one complex number representation (x+yi) can't be physical, and another (2 by 2 matrices of real numbers) might be physical? — fdrake

We've never managed to measure anything that is a 2x2 matrix either. We use matrices a lot -- they are useful, but they are constructs. I don't think nature knows about them.

What I think is a better criterion is whether we can do without them. Negative numbers are empirically indispensable, interference effects being a great example, electric charge being another. Complex numbers may also be indispensable, or they might just be efficacious. Given the way they enter into the equations, my feeling is that it's the latter, but I'm not trying to make that particular case in the OP. However complex things are at root, empirically they manifest as real.

But this only gives the "real paths" of the electron once the "boundary condition" on the other end is fixed, i.e. once the measurement already happened at the back screen. — SophistiCat

Yes. I think your question was: how do we get the Born rule? The Born rule is derived from each retarded path in the sum over histories overlapping with each advanced, conjugate path coming back from the screen. The Born rule would only apply to the real paths.

This doesn't explain any actual data though: we have no independent knowledge of those "real paths" besides what the interpretation tells us. What we have from experimental setup and observation are just the boundary conditions, the origins of the retarded and the advanced wavefunctions. — SophistiCat

True, but this is actually a more minimalistic interpretation of empirical data. It yields a single position on the back screen without magical collapse mechanisms or (hopefully) proliferating universes, and still yields the same interference effects as standard QM interpretations.

TQM, Copenhagen, MWI, Bohm etc. are all obliged to yield the same experimental predictions, having the same mathematics. The point here is more that the philosophical ramifications of an ideal screen in Copenhagen are naive, and that the fact that complex conjugates of solutions to the Dirac equation are also solutions to the Dirac equation, in fact the general idea that there's no obvious arrow of time in special relativity, does not support the assumption of such collosally irreversible and information-losing processes. There are more physically well-grounded and more rigorous approaches to understanding the same experimental data.

which is no more than what vanilla QM tells us and doesn't explain the really interesting bit, i.e. the measurement problem. — SophistiCat

There is possibly no measurement problem in this formulation, because the (numerically) real aspect of the wavefunction is never spread out across the screen. The electron travels from (r,t) to (r',t') by every possible path, but only to (r',t'). If you were to place a screen midway at r'', you wouldn't get the same paths, therefore no collapse.

It is, I think, impossible to prove that every path through every other possible value of (r',t') can be eliminated by considering the entire history and future of the electron (or, respectively, future and history of the hole(s) it overlaps with), hence the jokily-named not-many-worlds interpretation. But conversely it's impossible to prove that the electron does actually have a real probability to be found at any point on the screen. The former is simpler, however, and it is possible to state with absolute surety though that not every part of the screen is accessible that Copenhagen says is accessible.

Well, of course, if you take something that is usually represented by a scalar, such as height or weight, then a real number will be optimal as a mathematical representation. — SophistiCat

Well, the wavefunction is a scalar field :)

How does your (transactional?) interpretation recover the Born rule? — SophistiCat

From the overlap integral of the retarded wavefunction with the advanced wavefunction:



In transactional QM, this is the very meaning of the Born rule. It's not my transactional QM btw, it's been around a while I think.

How do you get the interference stripes in the double slit experiment? — SophistiCat

When a particle moves from event (r,t) to (r',t'), it still does so by every possible path (Feynman's sum over histories). If you sum up every possible r' at t' and normalise, you recover the wavefunction at t'.

Complex quantities are no more and no less physical than real quantities, tensors, vectors, and whatnot. They are all mathematical objects. — SophistiCat

Ah, I see. This is deeper than I'd realised. Simply multiply whatever complex number by whatever physical unit: we never see that. I see I have 10 fingers and that I'm 5.917 feet tall, but I have never weighed (12 + 2i) stone.

So if that makes the wavefunction real in a broad sense (which is fine by me), then the whole of it has to be real, not just the amplitude — SophistiCat

I'm getting confused now between ontologically real and real as in has no imaginary component. I started it, mea culpa. I'll rephrase.

The OP holds that the complex wavefunction is an ontic description -- or fair approximation to such -- of how particles propagate through space and time as we represent them. How we describe the relationship between time and space is intrinsically complex, just from straight relativistic vector calculus, which happens to be the language quantum field theory is written in. There are other languages for describing relativity that can do away with the imaginary number and it may well be that in future we can generalise QFT in a similar way; such an endeavour would be part of a general relativistic quantum mechanics. So I don't hold the complex wavefunction to be an ontic description of the particle itself, rather it encodes the ontology of the wavefunction in our spacetime representations accurately, e.g. encodes information vital for doing the physics.

Do you get most of your information from Wikipedia? — Metaphysician Undercover

No, I did something that has apparently never occurred to you: I got an education.

What's your objection to strong emergence?
— Olivier5

Basically, it's magic. — Pfhorrest

:up:

Agreed, and that's why I wouldn't do that. — Pfhorrest

By describing it as panpsychism (everything is conscious), you are doing that. Yes, you are demoting consciousness in this context to any physical response function, but that itself is a result of poor choice of terminology. We already have terminology for this. It seems logical to apply the general terminology to the special case. The other way round is, well, back to front.

My overall position is saying that whatever metaphysics is going on with human beings that may be required for our having of a subjective experience, that metaphysics is going on with everything and is not special to humans; the important difference between humans and e.g. rocks, that makes us conscious in the ordinary sense (access conscious), is only the difference in the function of a human vs a rock, not anything metaphysically different. — Pfhorrest

Ah okay, 'purely functional' as opposed to fundamentally metaphysical, not as in divorced from its properties. Yeah, with you on that. I forget that people want to insist we humans are a bit magic, so the distinction went by me.

P.P.S. If you're wondering about the half, that comes from the Schrödinger equation being a non-relativistic approximation. Energy is proportional to half the momentum squared in Schrödinger/Newton, while the square of the energy is proportional to the square of momentum in Dirac/Einstein. I never did the derivation for the Dirac equation, probably should.

P.S. I happened across this entire book on arxiv: https://arxiv.org/abs/1611.02738

You would have thought that a book on the ontology of the wavefunction would examine the question of its complex nature, but nope. The word 'complex' appears a total of 9 times, one of which is in its everyday sense. It's entire insight on this question is: Schrödinger was surprised.

But it did jog my memory. The wavefunction can be written as a real function multiplied by a complex phase defined everywhere (this is trivial: a complex number has magnitude and phase). The phase is important for interference effects, but makes no difference when it comes to observables. The former is why I believe in an ontic wavefunction, and the latter is why the wavefunction might be considered epistemic.

Also, that complex phase function is directly related to the probability current, while the real part is directly related to the probability density. In fact, a single-particle wavefunction can be written as $\nabla\psi = \frac{1}{2}\nabla n + i\frac{d\mathbf{j}}{dt}$, where n is probability density and j is probability current. I'm not sure that's ever been published... It was on my whiteboard for years but never made it into a paper.

Now recalling the four-current from relativity, we have $J = [n, i\mathbf{j}]$. (In tensor formulations we write the elements as real and move the imaginary part into the metric.) Again we see this relationship between a real spatial part and an imaginary momentum part, even without quantum mechanics.

So I'd venture that the complex nature of the wavefunction is to do with the relationship between space and time. It might not be something about the particle itself, but rather how we describe particles in space and time.

I’m mostly using psychological terminology for phenomenal consciousness just because that’s the terminology already used for it, but I can see the historical reasons for its use — Pfhorrest

No objection to that, but using the same terminology to describe the response of an electron to a photon, say, is much like saying everything is a horse. Sometimes metaphor is useful, such as in the talk of "the perspective of a photon" that Mr Bee so objected to earlier. It ceases to be metaphor and becomes misspeaking if you start taking it seriously though. Yes, psychology is ultimately just physical stuff reacting to physical stuff, but so is neurology, biology, chemistry and physics. What makes it psychology is that it is to do with animal minds, neurology: animal brains, biology: living systems, chemistry: structures of atoms, and physics: everything. It just seems like a category error to call physics 'psychology'.

I’m not trying to do that, and I don’t see how you can read that in to the passage you responded to. — Pfhorrest

My misunderstanding then. I read your previous threads in this series as establishing an equivalence between being and doing, one I agree with. What is a 'purely functional' thing, then?

That is still weak emergence, in that if you modeled the underlying system that that behavior emerges from, you would automatically model the emergent behavior (as in see that behavior emerge in your model; not that you would have a higher-level model of it). — Pfhorrest

Yes. I think perhaps it was just not a very illustrative example since it was just the statistical character of pretty much independent parts, whereas emergence really regards collective behaviour: new modes of elementary behaviour not possible with elementary systems.

Is it objectively subjective, or is it merely subjectively subjective? — unenlightened

:heart: Well put. I'm gonna steal that.

Another self indulgent spitball from me. Thank you for the free physics lessons. — fdrake

I think you're doing okay without me, dude :D

What stops complex quantities from being physical? — fdrake

It's a good question. We certainly don't measure something as having a complex value, which could be a cognitive or technological limitation. It might be that the wavefunction is a 'real' (existing) thing and we encode our ignorance about its underlying nature as a complex phase (e.g. a compact dimension).

Or it might just be a mathematical trick, like Cat's examples. According to the Hohenberg-Kohn and Runge-Gross theorems (and, um, the me theorem), the wavefunction is uniquely given by the charge and current density and the environmental fields, all real-valued. We just don't have a good way of dealing with these quantities directly: wavefunctions are easier.

My take in the OP is that the wavefunction has some kind of existence and the real-valued densities arise from considering retarded and advanced waves. I wouldn't go as far as saying that the complex wavefunction is an accurate depiction even within this quite literalist view.

Do you think that a hot object knows that the cooler object is cooler when it radiates heat? — Metaphysician Undercover

That would be unnecessary according to the OP. It is sufficient that each particle knows where it is going. The statistical emergence of thermodynamics would arise from the fact that trajectories from (r,t) to (r',t) are more probable than their reverse. Indeed, all of thermodynamics is derivable from QM (via statistical mechanics: in fact, that's how we were taught stat mech at my uni), without any notion of heat being forced in by hand.

And I'm sure you know that the definition of "black-body" is based in thermodynamic equilibrium. — Metaphysician Undercover

No, a blackbody radiator is a non-equilibrium thermodynamic system, that is: it is not in equilibrium with its environment. An oven is something that radiates in its interior. So it's the interior radiation that is in equilibrium. The oven as a whole is still non-equilibrium.

Since this idea which you have (I should call it an "ideal") that emission/absorption is reversible, is dependent on black-body conditions, it's practical significance is very limited. — Metaphysician Undercover

Again, the CPT (charge-parity-time) symmetry of quantum field theory is not a new idea of my own that I'm presenting for consideration. It is a known symmetry that is broken by a few rare processes. I'll give you a heads up now, since you keep making this error: very little of what I've presented in the OP is original. The new-ish bits are that a) one cannot draw conclusions about where a particle may be found at a given time by considering only that particle at the time, and b) that the birth and death of a particle are its true boundary conditions. Those might be considered novel or controversial.

Emission/absorption is only reversible when an object is at thermodynamic equilibrium, which is when emission will not occur. — Metaphysician Undercover

At thermodynamic equilibrium, the rate of emission equals the rate of absorption (clue's in the name).

Clearly you cannot "run the movie backward". The idea that you can take an object's radiation of energy to its surroundings, and turn it around such that you can represent it as it's environment radiating the energy to the object, is completely unjustified, and obviously wrong. — Metaphysician Undercover

That's precisely what a system in equilibrium with its surroundings does. But I was discussing fundamental processes, not statistical ones. Fundamentally, a particle moving from one position to another is reversible for instance, e.g. things are not constrained to move in the same direction along a given axis.

Have you ever heard of "mechanical efficiency"? Mechanical efficiency is always less than 1, because a mechanical system always loses energy to its environment, friction for example. — Metaphysician Undercover

Thermodynamics does not demonstrably lead to loss of information. In fact, conservation of information and entropy are related.

To say that the decimal expansion of some numbers, like π, never repeats begs the question of the definition of "repeat." And that because they do repeat, an infinite number of times in an infinite number of ways. Consider: the representing decimal numeral is made of ten fundamental parts, 0 through 9, and these repeated (an infinite number of times - infinity times - IT). Also the two-numeral combinations, 00 through 99, also repeated IT. And the three, 000-999, IT, and the four, 0000 through 9999 IT, and so on. — tim wood

This is covered in the video. Local features may occur an infinite number of times. This is not what periodicity is, however. For something to be periodic, the whole thing must be a single repeated pattern. So 110011110011110011... is periodic because the sequence as a whole is just the sequence 110011 repeated forever. Pi is not periodic.

But in ordinary usage, something being a mind means more than just being some kind of prototypical subject of phenomenal experience, or instantiating any old function or another. It means instantiating some specific kinds of functions that we recognize as mental. — Pfhorrest

A problem completely avoided by not using terminology regarding psychological phenomena to describe non-psychological phenomena. Put it this way: a horse is just a bunch of physical stuff reacting to and acting on a bunch of other physical stuff, and everything is like this. So everything is a horse? No. Psychological phenomena regard brains. It doesn't matter if there's no fundamental difference between a brain and a bowl of soup: it's a classification for specific kinds of things (or behaviours: to be is to do).

But I think that consciousness as we ordinarily speak of it is access consciousness, to be addressed later, and that access consciousness is a purely functional, basically mechanistic property that is built up out of, or weakly emerges from, the ordinary physical properties of the physical things that compose an access-conscious being. — Pfhorrest

Being itself is purely functional though, isn't it? You went to pains in previous threads to establish that there is no real distinction between to be (i.e. to have a bundle of properties) and to do (i.e. to have the potential to behave a certain way). Seems odd now to insist on a distinction between emergent properties and emergent function.

An example of this is temperature, which is a (weakly) emergent property of the motion of molecules in a substance: if you modeled the motion of all the molecules in a substance, you would end up modeling something that exhibited temperature for free, and if that was the scale you were interested in, you could usefully model just that aggregate property of temperature instead and ignore the details of the motion of individual molecules. I have no objection to such "weak" emergentism. — Pfhorrest

There's stuff in between this and strong emergence. Thermodynamic properties of gases in a box are just statistical, large-scale descriptions of fundamental particulate behaviour. However, there is such a thing as collective behaviour. A phonon is an example of this. While phononic behaviour is just motion, you need at least two interacting bodies for these particular modes of motion to emerge. Likewise, while chemical bonds are just modes of electrostatic attraction, they are only possible when you have two or more atoms. There's important stuff between statistics and magic (strong emergentism). So the difference between the thermodynamics of gases, liquids, and solids is derivable but not comprehensible in terms of the dynamics of individual atoms: you have to consider at least two (often more) of something before some behaviours are possible.

Is quantum theory the "set theory" of physics? Weird at first but providing a foundation? :chin: — jgill

Quantum field theory is the most foundational theory we have, underpinning everything we know about except gravity. It might be that QFT can be generalised to curved spacetimes but it's probably more likely that there's a more fundamental theory out there somewhere, something like string theory maybe. Check out Kakuza-Klein theory for why string-type theories are expected: https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory?wprov=sfla1

they are paying the addicts $300 in exchange for a verbal agreement that they will get sterilized. Many do follow through with this, but some women just take the 300$ and use it for other things. — rsgkh

Thanks. Then the answer is no, I think. It is illiberal to compel someone to give up their future liberty by exploiting their current desperation.

Utilitarianism vs Libertarianism on: Should private charities be permitted to pay female drug addicts $300 to undergo sterilization?

I found this very interesting. What do you guys think Libertarianism vs Utilitarianism would argue? — rsgkh

Just to clarify... Is the charity paying for the sterilisation or paying female drug addicts to get sterilised?