Weinberg's Problem Amongst Quantum Mechanics Is Non Fifty-Fifty Wrong

Bill Zajc too Luke Lea have got simultaneously sent me a link to a novel (or future) article past times Steven Weinberg inwards The New York Review of Books,

previous blog posts, Schrödinger's equation for the density matrix is just a straightforward rewriting of those Liouville's equations.

It's absolutely touchstone for probabilities to evolve according to about laws. That's what probabilities did inwards classical physics, too. Bayes' theorem is just about other illustration of a police describe that fully determines the alter of probabilities, inwards this illustration inwards a discrete step. Bayes' "deterministic" police describe for the alter of probabilities later evidence is collected has its counterpart inwards quantum mechanics equally good – it's the reduction of the moving ridge business office later a measurement. The rattling outcome of the measuring is non fully determined when probabilities are betwixt 0% too 100% – but that arguing was truthful inwards classical physics, too. Influenza A virus subtype H5N1 probability dissimilar from 0% too 100% agency too has e'er meant that the outcome is unknown i.e. non fully determined.

When it comes to well-defined laws governing the development of probabilities inwards time, it's just a manifestly stupidity to propose that these laws are "troubling" inwards whatever sense. Quantum mechanics doesn't alter anything nearly the pregnant of probabilities, their human relationship to imperfect knowledge, the existence of well-defined equations past times which these probabilities evolve equally good equally discontinuous Bayesian/collapse changes past times which the probabilities jump later an observation. The alone affair that is novel inwards quantum mechanics is the dubiety regulation (due to the nonzero commutators) which, amidst other things, forbids whatever perspective inwards which ii generic observables are perfectly known at the same moment. The nonzero commutators larn inwards unavoidable to utter nearly probabilities betwixt 0% too 100% i.e. nearly imperfect knowledge. But what the "knowledge", "imperfect", "probability" etc. hateful is just the same equally it e'er was.

Bill Zajc has picked this judgement from Weinberg's essay equally the predicted locus that causes irritation:

So if nosotros regard the whole procedure of measuring equally beingness governed past times the equations of quantum mechanics, too these equations are perfectly deterministic, how reach probabilities come inwards quantum mechanics?

Probabilities have got been a portion of quantum mechanics from the kickoff too they have got to hold out a portion of it past times Definition – or because of the universal postulates of quantum mechanics. Thanks for asking. The enquiry how "probabilities got to quantum mechanics" is equally light-headed equally the enquiry how the terrestrial life forms got to Earth. "Terrestrial" is an describing word meaning that they are on footing hence something is terrestrial just when it's on Earth. In the same way, quantum mechanics is a theory whose mathematical variables (I hateful mainly the moving ridge business office now) that may hold out evolved according to well-defined ("deterministic" is misleading) equations have got to hold out (physically interpreted as) probability amplitudes. If it didn't demand probabilities, it wouldn't hold out quantum mechanics.

In next paragraphs, Weinberg tries to promote theories that say that the underlying theory doesn't have got whatever probabilities – the underlying theory violates the dubiety regulation because everything telephone commutation is sure inwards it. Sorry, all such attempts are guaranteed to neglect too alone deluded folks report this sort of garbage inwards the initiatory of all place. It's an established scientific fact that the uncertainties i.e. probabilities betwixt 0% too 100% cannot hold out eliminated from the telephone commutation laws – this established scientific fact is known equally the dubiety principle. The enquiry whether \(x\) too \(p\) – which tin demonstrably hold out measured – are knowable at the same 2nd is mathematically equivalent to the enquiry whether \(xp-px\) is zero. The deviation \(xp-px\) may hold out measured too was measured experimentally too the result, \(i\hbar\), is non zero. In fact, it's known amongst the precision 1 portion per billion. The peril that it's null is excluded at to the lowest degree at the one-billion-sigma confidence level. It's just a full-blown denial of reality to propose that the observables commute i.e. that they are simultaneously perfectly knowable.

Weinberg tries to introduce decoherence equally something that provides us amongst the pseudorandom generator. That's completely wrong. Decoherence doesn't collapse the density matrix to a item outcome – i.e. a diagonal matrix amongst zeroes too the lay out 1 once. Decoherence is an guess description of the development of a density matrix whose in conclusion resultant is a diagonal matrix amongst diagonal entries (probabilities) which are numbers inwards betwixt 0 too 1 that add together upwards to one. But the lay out of diagonal entries strictly inwards betwixt 0 too 1 is greater than 1 – all possible outcomes are confirmed equally possible later decoherence takes place. Decoherence inwards no trend changes the fact that the outcomes are random too alone probabilities are calculable.

So almost everything that Weinberg writes nearly decoherence is just wrong. What he writes nearly the right quantum mechanics is fifty-fifty stinkier cr*p, however:

One response to this puzzle was given inwards the 1920s past times Niels Bohr, inwards what came to hold out called the Copenhagen interpretation of quantum mechanics. According to Bohr, inwards a measuring the terra firma of a arrangement such equally a spin collapses to 1 resultant or about other inwards a trend that cannot itself hold out described past times quantum mechanics, too is genuinely unpredictable. This reply is right away widely felt to hold out unacceptable.

Sorry but the unpredictability of the outcomes is an established fact that every credible physicist agrees amongst too alone cranks may give away it "unacceptable". If Weinberg considers the intrinsically probabilistic grapheme of quantum mechanics to hold out just an idiosyncrasy of Niels Bohr's, universities inwards Cambridge too Austin should likely demand him to render the salaries he has received equally an teacher of quantum mechanical courses.

There seems no trend to locate the boundary betwixt the realms inwards which, according to Bohr, quantum mechanics does or does non apply.

There is an slowly trend to locate it. The boundary doesn't be or is at infinity. Quantum mechanics applies everywhere. The alone boundary that is found at a "finite place" too that may hold out discussed is the boundary bounding the regimes which are also described past times classical physics or classical concepts reasonably well. The shape of this boundary may hold out calculated from quantum mechanics too has a complicated shape depending on the sort of problems nosotros calculate. But quantum mechanics applies on both sides of this boundary! Is it already hence bad amongst Weinberg that he misunderstand this piddling point?

An observer also invents a boundary, the Heisenberg cut, betwixt himself too the world he straight perceives – the observer side of the cutting whose data may hold out treated equally classical information; too the observed side that needs the handling inwards damage of probability amplitudes. The side treated classically has to concur amongst the fact that classical physics is a practiced information. But otherwise the cutting is arbitrary too objects on both sides of the cutting may seem on the quantum side of the cutting equally defined past times about other observer.

As it happens, I was a graduate pupil at Bohr’s institute inwards Copenhagen, but he was rattling neat too I was rattling young, too I never had a peril to inquire him nearly this.

Dr Weinberg may easily inquire me. I tin laissez passer on too I have got given Bohr's answers – although likely much to a greater extent than clearly stated than Bohr could. ;-)

Otherwise, Bohr remains rattling neat fifty-fifty now, when he's dead, at to the lowest degree inwards the extent to which he understood the telephone commutation properties of the laws of physics.

Today at that spot are ii widely followed approaches to quantum mechanics, the “realist” too “instrumentalist” approaches, which sentiment the root of probability inwards measuring inwards ii rattling dissimilar ways. For reasons I volition explain, neither approach seems to me quite satisfactory.

The separation to "realist" or "instrumentalist" may hold out interpreted either equally a separation of actual physical theories that are used to brand predictions or equally a separation of people's preferred linguistic communication too philosophy to recollect nearly partly unphysical, philosophical questions. When it comes to the theories, the province of affairs is unambiguous. "Realist" theories are wrong, stupid, too excluded because they just can't reach right predictions for all the phenomena spell all the right theories require the "instrumentalist" attitude.

When nosotros utter nearly language, the give-and-take "instrumentalist" may audio misleading to many people equally good because of ii reasons. One is that it suggests (and Weinberg explicitly confirms the hidden meaning) that at that spot is something incomplete nearly quantum mechanics too quantum mechanics is alone "useful for a practical man". I don't recollect it's true. Quantum mechanics is almost for certain consummate too no "deeper" description may exist. The 2nd argue why "instrumentalism" may hold out misleading is that the telephone commutation quantum mechanical theory allows us to utter over whatever "instrument" – it doesn't interruption downward whatever nosotros withdraw hence the suggested dependence on the "instruments" is almost equally misleading equally if nosotros suggested that quantum mechanics is "anthropocentric". What the application of quantum mechanics needs isn't observers that await just similar humans amongst instruments that await just similar those produced past times humans. What the application of quantum mechanics needs is just observers that tin larn aware of the values of about physical observables.

At whatever rate, all these questions were already completely settled inwards the mid to belatedly 1920s too no evidence whatsoever has emerged inwards the next xc years that would dot about problem amongst those conclusions.

OK, Weinberg interprets, reinteprets, too misinteprets the give-and-take "instrumentalism" inwards diverse ways. For example, he claims:

It seems to me that the problem amongst this approach is non alone that it gives upwards on an ancient aim of science: to say what is really going on out there.

If past times "what is really going on out there", he agency that at that spot is a theory that violates the dubiety regulation too admits the description of all the telephone commutation variables that are observable inwards regulation too completely sure at the same moment, too the residue of his essay indicates that that's just what he "wants", too then the reply known from 1925 is that these theories – known equally theories of classical physics – have got been ruled out. They are f*cking incorrect because they violate a telephone commutation axiom of physics, the dubiety principle.

Values of (non-commuting) observables aren't perfectly knowable at the same 2nd too this is a fact that every feasible police describe of physics has to concur with. This is an of import fact describing what is really going on inwards Nature spell Weinberg's fantasies nearly the world without the dubiety regulation are what is never going on Nature. They're old scientific discipline that is just equally debunked equally creationism too if Weinberg believes that he is behaving to a greater extent than reasonably than the creationists towards the scientific evidence nearly these telephone commutation questions, too then he is just fooling himself – too others – too abusing the fact that the ideologically biased academy surroundings allows about types of stupidity to a greater extent than than others.

When Weinberg says that it's "troubling" when quantum mechanics doesn't allow the fundamental, inwards regulation observable quantities to hold out perfectly known at the same moment, i.e. when he straight assaults the dubiety principle, he displays just the same sort of metaphysical bigotry equally a creationist who finds Darwin's theory "troubling" because it's non compatible amongst the constancy of species according to the Bible, God's one-week creation contract, or amongst about verses inwards the Bible that have got described that contract. Science has only proven these prejudices wrong. Species have got been scientifically proven to evolve too observables have got been scientifically proven to have got nonzero commutators i.e. to hold out simultaneously unobservable amongst perfection.

Thus humans are brought into the laws of nature at the most telephone commutation level. According to Eugene Wigner, a pioneer of quantum mechanics, “it was non possible to formulate the laws of quantum mechanics inwards a fully consistent trend without reference to the consciousness.”

This criticism is absolute rubbish, too. Wigner stated that quantum mechanics requires consciousness. Consciousness isn't the same affair equally humans. Consciousness is just a "spiritually sounding" synonym of the mightiness of an observer to hold out aware of a measured value of an observable. But the observer capable of "feeling" this data doesn't have got to resemble a human inwards whatever way. It may hold out a smart chimp or a silicon-based estimator or anything else. The thought that members have got about exceptional features that split upwards them from the residue of the Universe is a light-headed medieval superstition. And it's Weinberg, non Wigner, who implicitly assumed this superstition.

Wigner alone said that quantum mechanics needs an observer – too presented this fact inwards words that people who assist nearly their spiritual life similar to use. But the content is just the same equally the content of about universal postulates of quantum mechanics.

After additional confusing paragraphs nearly humans, Weinberg correctly says that "objective probabilities" are untenable. Yes, probabilities at a item province of affairs must e'er cite to the terra firma of heed of person who knows something – too it depends whom nosotros pick. Probabilities at a given 2nd are e'er observer-dependent or subjective. Quantum mechanics allows us to calculate values of probabilities according to objectively valid laws of physics. But the resulting probabilities have got to hold out interpreted equally subjective probabilities. In a item situation, probabilities are e'er subjective. And that's what feasible laws demand according to quantum mechanics.

Some to a greater extent than paragraphs utter nearly the "trouble" amongst "realist" theories. I recollect that it's practiced that he sees the problem but he doesn't encounter the primary problem of those theories because he shares the basic misunderstanding of the concepts amongst the champions of these pseudoscientific "realist" memes. I don't desire to read these paragraphs carefully.

Strange equally it is, the entanglement entailed past times quantum mechanics is really observed experimentally. But how tin something hence nonlocal stand upwards for reality?

Entanglement doesn't stand upwards for whatever nonlocality. There is null nonlocality inwards quantum acre theory on a Minkowski background. The absence of nonlocal effects is mathematically encapsulated inwards the vanishing (graded) commutators of spacelike-separated acre operators. The entanglement is null else than the most full general correlation betwixt ii subsystems that have got previously interacted (or have got mutual ancestry) – which explains why the correlation is possible inwards a local world – too expressed inwards the fully quantum mechanical description of the moving ridge business office (which allows about properties of diverse correlations that wouldn't hold out possible if the world were classical).

What too then must hold out done nearly the shortcomings of quantum mechanics?

What must hold out done for the idiotic utter nearly shortcomings of quantum mechanics travel away is for totally confused people similar Weinberg to close upwards – or, fifty-fifty better, close upwards too calculate. Nothing else is needed, null else has been needed since 1925. Quantum mechanics is a perfectly consistent too consummate framework for studying too applying theories that depict everything inwards Nature at the most telephone commutation level.

Thankfully, Weinberg's initiatory of all reply is "shut up" but he utterly fails to apply it to himself. He must believe that he stands higher upwards the laws of quantum mechanics. He doesn't. No 1 does.

The remaining portions of his essay say a few words nearly the Ghirardi-Rimini-Weber "objective collapse" theories too Weinberg's ain efforts to experimentally examine that quantum mechanics is incorrect – too what he says is null less than that. Sorry, all these things are incorrect for the reasons I have got described many times too it is guaranteed that this sort of "research" won't atomic number 82 to anything useful.

Years ago, I was alone gradually noticing weird comments nearly quantum mechanics that Weinberg sometimes made. I cannot hold out 100% sure whether the transformation was generally due to Weinberg's becoming a to a greater extent than full-fledged anti-quantum zealot, or due to my increasing allergy to these falsehoods that Weinberg was proverb nearly quantum mechanics. I reach believe it's mainly the former.

At whatever rate, I consider Weinberg to hold out a 100% anti-quantum zealot – too a full-blown peer of Gerard 't Hooft – at this point. It's sad. It was likely the in conclusion text past times Weinberg nearly the foundations of physics that I wanted to (partly) read.



Off-topic: Willie Soon has sent me documents showing that the IPCC has adopted a novel catastrophic scenario. Higher CO2 levels touching titanium dioxide nanoparticles too later several additional causal influences captured past times the 55-million-view video above, this threatens rice inwards China. ;-) Good job, guys. Time to withdraw heed "You're fired".