Quantum theory cannot consistently pull the usage of itself (Nature).Note that Renner has arguably done to a greater extent than or less non-rubbish piece of employment inwards the quantum information theory but equally explained inwards an unbelievable video, he also employs a grouping of women who brag to last f*cking sixteen hours a day, going from 1 pregnancy to another, together with existence paid equally "physicists" – from to a greater extent than or less European taxpayers' coin – for allowing their names to last used inwards to a greater extent than or less ludicrous papers well-nigh the "quantum foundations".
In April, I discussed 1 of these crackpot papers inwards which Renner together with Frauchiger asserted that quantum mechanics required many worlds. They used a straightforward physical organisation of 2 qubits – together with several bases of their 4-dimensional Hilbert space.
You're invited to click at the hyperlink inwards the previous paragraph together with elbow grease to retrieve to a greater extent than or less of the equations. Why? Because the novel newspaper inwards Nature uses exactly the same states together with bases inwards the 4-dimensional Hilbert space. Just the determination is dissimilar this time: Instead of "proving" many worlds, they claim to "prove" a contradiction of quantum mechanics inwards the presence of people's thinking well-nigh the other people's thinking.
Needless to say, no such contradiction exists together with it's a crackpot paper. What's going on? Let us repeat to a greater extent than or less mathematics. Alice A, renamed equally \(\bar F\) (Wigner's f*ck toy inwards the bar) inwards the novel paper, prepares ii qubits inwards the state\[
\ket\psi = \frac{ \ket{h}_A\ket{0}_B+\ket{t}_A\ket{0}_B+\ket{t}_A\ket{1}_B }{\sqrt{3}}
\] Now Bob, renamed equally \(F\) (Wigner's f*ck toy exterior the bar) inwards the novel paper, measures the 2nd qubit, whether it's nil or one. Two to a greater extent than people, \(W\) together with \(\bar W\), stair out the labs \(L\) or \(\bar L\), respectively, which comprise the people \(F\) together with \(\bar F\), respectively. And they brand diverse bases relevant for their measurements.
One of them makes the footing "ok/fail,0/1" relevant; the other makes "h/t,ok/fail" relevant. For the ii qubits, ok/fail states are defined equally the uncomplicated "sums" or "differences"\[
\begin{eqnarray}
\ket{\rm fail,ok}_A &= \frac{\ket {h}_A\pm \ket {t}_A}{\sqrt{2}}\\
\ket{\rm fail,ok}_B &= \frac{\ket {0}_B\pm \ket {1}_B}{\sqrt{2}}
\end{eqnarray}
\] We know all the relationships betwixt the bases to write 3 to a greater extent than forms for \(\ket\psi\) defined above:\[
\begin{eqnarray}
\ket\psi &= \sqrt{\frac{1}{12}} \ket{\rm ok}_A \ket{\rm ok}_B
- \sqrt{\frac{1}{12}} \ket{\rm ok}_A \ket{\rm fail}_B+\\
&+\sqrt{\frac{1}{12}} \ket{\rm fail}_A \ket{\rm ok}_B
+ \sqrt{\frac{3}{4}} \ket{\rm fail}_A \ket{\rm fail}_B
\end{eqnarray}
\] together with \[
\begin{eqnarray}
\ket\psi &= \sqrt{\frac{2}{3}} \ket{\rm fail}_A \ket{0}_B
+ \sqrt{\frac{1}{3}} \ket{t}_A \ket{1}_B+\\
&=\sqrt{\frac{1}{3}} \ket{h}_A \ket{0}_B
+ \sqrt{\frac{2}{3}} \ket{t}_A \ket{\rm fail}_B .
\end{eqnarray}
\] Great. The mathematical content of the "paradox" remains just the same equally inwards their older paper. But right away all the transitions from the bases are reframed equally "thinking of 4 people" who apply to a greater extent than or less "what practise you lot attention what other people think" methodology.
Mathematically, the "paradox" is claimed to arise because inwards the "ok/fail,ok/fail" basis, the final result "ok/ok" has the probability \(P=1/12\) to tumble out assuming the same initial solid soil \(\ket\psi\). On the other hand, inwards the bases privatized past times the people \(W\) together with \(\bar W\) together with assuming that "ok,ok" was measured equally the right solid soil from the "ok/fail,ok/fail" basis, 1 may simultaneously fence that the solid soil has drib dead "h,1" because 1 of these people has ruled out "ok,0" (and thence proved "ok,1") together with the other has ruled out "t,ok" (and thence proved "h,ok").
Just similar inwards the previous paper, they basically claim that the solid soil is simultaneously inwards \(\ket\psi\) together with inwards "ok,ok". But that's non possible because they are ii dissimilar states. Every observer, together with it is truthful for their 4 people equally good equally the remaining 7.5 billion people on Earth, together with also for all the non-human observers if at that spot are any, has to stair out something well-nigh the initial state. Depending on what the given soul has learned, the solid soil he uses to predict farther measurements may last either \(\ket\psi\) or "ok,ok" – or something else – but non both because these ii states are damn different. They yield dissimilar predictions. One of the states \(\ket\psi\) allows to a greater extent than or less outcomes forbidden past times "ok,ok", together with vice versa. Their "inequality" is a symmetric human relationship together with at that spot is no agency to process 1 of these states equally a "refinement" of the other state.
So if the solid soil of the ii labs \(L,\bar L\) is measured first, "ok/ok" has the probability \(P=1/12\) which is nonzero piece "h,1" has the probability zero. On the other hand, if the solid soil is firstly measured relatively to the "ok/fail,ok/fail" basis, nosotros may acquire "ok,ok", together with "h,1" becomes a possible outcome of the measuring afterwards. If a measuring is performed, the solid soil is changed.
Whether a measuring was performed is a subjective query – the measuring is an human activity past times which an observer (and at that spot may last unequivalent ones) learns well-nigh the value of an observable. Does this subjectiveness permit to a greater extent than or less contradiction, assuming that nosotros permit the people to mean value how other people think?
Not actually because a measuring done past times observer O1 has obvious consequences from O1's betoken of persuasion (the collapse of O1's moving ridge function) but that doesn't hateful that it doesn't accept consequences from the other observers' viewpoint. The other observers O2,O3,O4 pull the measuring differently – equally an interaction of O1's atoms amongst external objects that creates to a greater extent than or less entanglement betwixt her encephalon together with the external objects – but fifty-fifty from their viewpoint, the presence or absence of the measuring withal changes the experimental situation.
So according to all observers, the "h,1" outcome is impossible at the beginning, after the solid soil \(\ket\psi\) is prepared, but if a measuring of "ok/fail,ok/fail" is firstly performed, past times "oneself" or "another human", this changes the province of affairs together with "h,1" becomes possible.
In both papers, Renner together with Frauchiger constantly assume that the presence of a measuring does not modify anything, at to the lowest degree from to a greater extent than or less observers' viewpoint, but that's just rubbish together with that's the elbow grease of all their difficulties amongst quantum mechanics.
P.S.: They formulate their wrong theorem equally a proof that at to the lowest degree 1 of the assumptions Q,S,C must fail. The assumptions basically say:
Q: When quantum mechanics allows an observer to calculate the probability \(P=1\) of an outcome, he may enjoin the suggestion amongst certainty.Now, Q is to a greater extent than or less "validity of quantum mechanics", so it's violated past times to a greater extent than or less (four, inwards their table!) theories that actually disagree amongst the predictions of quantum mechanics. due south seems similar basic logic but they frame it equally the "single outcome" axiom, so it's violated inwards the many worlds pic (contradictory outcomes are all truthful – somewhere).
S: When something is measured \(L=\lambda_1\), 1 may enjoin that \(L\neq \lambda_1\) is impossible.
C: If an observer O1 may create upwards one's heed that the observer O2, past times using quantum mechanics, may create upwards one's heed she is sure enough well-nigh something, so O1 may last sure enough well-nigh it, too.
And it's "C" (compassion?) that is said to last violated past times the "Copenhagen Interpretation". And that's the claim they adapted for the title. But it's only non truthful that the axiom "C", equally they accept written it down, is invalidated past times proper (Copenhagen) quantum mechanics. If you lot tin give the axe legitimately essay out that to a greater extent than or less other observer may brand a determination to last certain, given assumptions that you lot also know to last correct, so you lot may brand the really same determination yourself.
Their invalid "proof" that the "Copenhagen Interpretation" requires to abandon "C" boils downwardly to their wrong supposition that it doesn't matter, from to a greater extent than or less observers' viewpoints, whether an observable was measured (by someone else). But the measuring of a quantity whose outcome isn't sure enough at the minute always changes the province of affairs – together with it changes the province of affairs from all observers' viewpoint.
People who withal elbow grease to essay out an inconsistency of quantum mechanics inwards 2018 are cretins.