Unpublished Schrödinger manuscript describes a hidden-variable update rule

Updating a hidden variable after a polarizer

ScienceAlert reports that Flavio Del Santo of the University of Geneva brought to light a three-page Schrödinger manuscript written sometime after November 1944. The account says Schrödinger challenged an argument that hidden variables could not explain photon-polarizer outcomes, using a variable that could take values between zero and one. It further says his model included a deterministic update rule after a photon passes through a polarizer.

The supplied report does not provide a comparable prior measurement or consensus baseline. It says the manuscript had remained unpublished in an Austrian archive and that the 1940s debate is largely forgotten today.

The newly surfaced manuscript reportedly adds an explicit rule for updating a photon's hidden variable after it passes through a polarizer, extending the model to successive measurements.

If the account is accurate, the manuscript supplies a concrete historical example of a hidden-variable model designed to reproduce quantum predictions across successive measurements. It also complicates a simple portrayal of Schrödinger as committed to determinism: the article says he defended determinism's possibility without necessarily endorsing it.