Wednesday, September 22, 2021

Rovelli Defends his Favorite QM Interpretation

Physicist Carlo Rovelli has written a defense of The Relational Interpretation of Quantum Physics:
Relational QM is a radical attempt to cash out the breakthrough that originated the theory: the world is described by facts described by values of variables that obey the equations of classical mechanics, but products of these variable have a tiny non-commutativity that generically prevents sharp value assignment, leading to discreteness, probability and to the contextual, relational character of value assignment.

The founders expressed this contextual character on Nature in the “observer- measurement” language. This language requires that special systems (the ob- server, the classical world, macroscopic objects...) escape the quantum limi- tations. But nothing of that sort (and in particular no “subjective states of conscious observers”) is needed in the interpretation of QM. We can relinquish this exception, and realise that any physical system can play the role of a Copenhagen’s “observer”. Relational QM is Copenhagen quantum mechanics made democratic by bringing all systems onto the same footing. Macroscopic observers, that loose information to decoherence, can forget the labelling of facts.

Go ahead and read the 20 pages if you want, but I will save you some trouble. It is pretty much the same as the Copenhagen Interpretation that you find in textbooks.

Apparently it bugs him that some descriptions of Copenhagen refer to a conscious observer, and that offends him, so he just calls everything an observre and doesn't care if it is conscious or not. If it is not consicous, then it may not figure out what the wave function is supposed to be, but it doesn't have to match anyone else's wave function, so nobody cares.

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