The Unhappy Nobel Laureate in Physics 2022

John Clauser, Nobel Prize in Physics 2022 joint with Alain Aspect and Anton Zeilinger for experimental work in Quantum Mechanics QM, expressed in his Nobel Lecture that he does not understand the theory of QM. This appears a bit contradictory because his work supposedly says something about the meaning the same theory as expressed in the Prize motivation: 

• for experiments with entangled photons, establishing the violation of Bell inequalities
• and pioneering quantum information science. 

What Clauser cannot understand is the physical meaning in his 3d physical lab space of the QM wave function $\Psi (x1,x2,...,xN;t)$ for an atomic system with $N>1$ electrons satisfying a Schrödinger equation, as a function of $N$ 3d spatial variables $x1,x2,...,xN$ altogether forming a configuration space of dimension $3N$. 

This was the problem which confronted Schrödinger when generalising from the Hydrogen atom with $N=1$ with configuration space = lab space, to Helium with $N=2$ and a 6d configuration space different from lab space. A confrontation which forced Schrödinger to leave QM in despair, leaving Bohr and Born to seek to rescue the situation by giving $\Psi$ a probabilistic interpretation as possibility over configuration space instead of actuality over physical space. Modern atom physics was so born by a heroic sacrifice of actuality or physicality as a most essential aspect of classical physics.

What Clauser expresses is that the step from actuality to possibility created problems, which still after 100 years have not been resolved. 

The root of the problem is that Schrödinger's equation was generalised from $N=1$ to $N>1$ by a purely formal mathematical procedure by simply adding more variables into a $3N$-dimensional configuration space different from lab space. 

Real Quantum Mechanics offers a generalisation retaining actuality in 3d. Other generalisations have been suggested including the Many-Worlds theory by Wheeler and the Pilot Wave theory of Bohm, both with unclear actuality.