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Jonathan Kerr, a new featured anti-quantum warrior

Dark energy an error? reviewed a one-month-old Korean preprint claiming to have made measurements and showing that type IA supernovae's light intensity is correlated with their population age, after all. Such an "astrophysical" drift of the "standard candles" may mimic the "cosmological" behavior attributed to dark energy and dark energy as extracted from the supernovae may therefore be spurious. Of course it's plausible (and would be far-reaching if true), we may hear from others soon... Well, Rubin+Heitlauf have already claimed that the Koreans err in their treatment of distributions and even neglect the motion in the Solar System. Colin et al. (who wrote a similar paper to the Koreans in August 2018) disagree and they even criticize the corrections from the Solar System motion as "arbitrary corrections". Sorry, this is silly. Failing to recognize Galileo's "And yet it moves" is a pretty serious and unquestionable mistake. Galileo isn't an "arbitrary correction". ;-)
We haven't discussed the "mainstream" media's hype about a perfectly deluded critic of quantum mechanics for a few weeks.

Well, Max told us that there is no hiatus. The Telegraph's Sarah Knapton (also reprinted at MSN) chose the title
New theory of quantum mechanics shows matter is not in the eye of the observer
We're promised that a 19-page-long paper (PDF) will soon appear in a "well-respected peer-reviewed journal". By a complete accident, a popular book by the author, Jonathan Kerr, just appeared in the bookstores (click at the icon in the corner) and the Telegraph readers are encouraged to buy it.

Knapton modestly tells us that by working on this cottage in Surrey, South East England, Kerr has solved a problem that "has puzzled scientists for nearly 100 years". Surely you have never heard such a statement before! The likes of Rovelli and Turok praise the author, too.

Well, in reality, the 19-page-long "paper" is just another, the 15,825th repetition of all the general delusions of the type "quantum mechanics has to be completely wrong"; incidentally, there isn't a single equation in the "paper"! So this "exceptional thinker" tells us that he has removed the "woo-woo" from quantum mechanics, the mind, consciousness, and the observer as well, indeed.

Kerr isn't an exceptional thinker. He has just proven to belong to the bottom 8 billion who simply don't have the brain capacity to understand modern physics, not even the very basics. If you ask any of the 8 billion people at the bottom of the understanding, they will tell you exactly what Kerr says. The fundamental description of the physical phenomena cannot possibly depend on observers and their observations.

Well, for almost a century, actual competent physicists have known that this dependence exists, is fundamental, and is impossible to be removed or replaced by anything. In other words, matter is in the eyes of the observer and physics can never return to the point where it was otherwise. Quantum mechanics is a theoretical framework whose application always demands some "facts" – the "observations" – to be specified. We normally assume that it is done by "somebody", the "observer", who has actually perceived the outcomes of such observations. This perception in principle contains a "subjective" aspect and this aspect cannot be removed from the laws of physics (in practice, the degree of subjectivity may be very low but it is simply not zero). If it could be removed, classical physics would be enough but classical physics isn't enough.

To be sure that the gullible readers are sufficiently indoctrinated, Knapman repeats the same claim about "interactions not observations" at least four times:
He thinks that it is actually impossible to measure anything without a tiny interaction taking place and it is that ‘bump’ that tells the particle where it is in space and fixes its form.

“But when we make a measurement, we have to cause an interaction - bumping bits of matter together - and people started to suspect that the interaction necessary for the measurement is what causes it.

When a measurement is made, the experimenter has to cause an interaction, and when two particles bump together, they 'get their bearings', and find out where the cylinders they live on are in space.

“The idea that one should replace the notion of measurement to one of interactions is a key one. Measurement cannot be anything foundational because it doesn’t mean anything.
You can repeat it 4 times or 1917 times but the statement will always be totally and fundamentally wrong and the wrongness has been known for nearly a century, indeed. An undergrad who makes any of the statements that are quoted above should simply get a failing grade in her QM exam and that should be the end of the story.

The correct theory – which we call "quantum mechanics" – needs to distinguish generic interactions from observations.

They may be "physically the same events" when all people's perspectives are conflated but the application of quantum mechanics does require to pick which degrees of freedom are "observed" and which belong to the "observer"; equivalently, the application of quantum mechanics does require one to pick a perspective, an observer. The interactions with this chosen observer are called the measurement and their description is and has to be different than the description of the observed interactions.

Observed interactions are processes in which the wave function and the density matrix evolve unitarily,\[

\rho \to U \rho U^\dagger\quad {\rm or} \quad \ket\psi\to U \ket\psi

\] and the wave function is therefore generically evolving to complicated superpositions. When they involve several subsystems (which may include another human), almost all such superpositions end up being entangled states. Note that I have already surpassed Kerr by the number of equations. ;-)

However, when such an event involves an observer who has learned the result, the event is an observation and its mathematical description is very different. The wave function or the density matrix "collapses" to an eigenstate of the measured operator \(L\). The collapse may be described by a projection operator\[

\rho \to P \rho P^\dagger \quad {\rm or} \quad \ket\psi\to P \ket\psi.

\] Note that this transformation differs from the previous one by the replacement of \(U\) with \(P\). But this makes a big difference because \(U\) is a unitary operator and generically or always,\[

U\neq U^\dagger, \quad UU^\dagger = U^\dagger U = {\bf 1}.

\] On the other hand, the operator \(P\) is a Hermitian projection operator\[

P = P^\dagger, \quad P^2 = P^\dagger P = P.

\] They're completely different things. The unitary transformation preserves the information and (with the dagger added), it squares to the identity operator. The projection operator erases most of the information and it squares to itself. The projection operator is what mathematically encodes the "emergence of a fact", namely the outcome of an observation. No "new facts" are created during the regular, unitary processes (and interactions).

To describe any process, quantum mechanics needs both, interactions and observations. Observations are needed because facts – sharp well-defined outcomes of measurements – exist; the observations are always irreversible (except for \(P=1\), projection operators don't have inverses) and create a new fact with the help of Nature's random generator.

Interactions are needed because the world evolves, amplitudes demonstrable interfere when things are not observed, and this evolution seems to be reversible. To separate them from each other, it indeed needs a vantage point to distinguish perceived facts from hypothetical processes, i.e. it needs observers. Physicists have known these conceptual laws for almost a century, from the 1920s. It took a few decades for them to figure out that the old picture of classical physics which didn't need any special "observations" and "observers" was ruled out and hopeless but they just did it.

Everyone who fails to understand this basic point in 2020 is a child who was left behind, not a genius. Everyone who praises claims about the "possibility to remove observers from physics" is a crackpottery snake oil salesman. Everyone who claims that a stupid anti-physics paper with 0 equations is a "new theory of quantum mechanics" is scientifically illiterate and absolutely incompetent to write articles about science. Everyone who claims that the statement "observers need to and can be removed from physics" makes someone original is a downright liar because thousands of intellectually limited people who have said the exact same wrong thing have been praised by the media, most of them just in the recent decade. Dozens of completely wrong popular books with this exact statement were published just in the recent 5 years.

Everyone who still thinks that he is being informed about the developments in theoretical physics by reading crap similar to this Knapman's nonsense is a hopelessly brainwashed sheep who is completely incapable of critical thinking, even in the easiest cases.

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