Seminar by Mark Srednicki (University of California, Santa Barbara): “Probability in Quantum Mechanics”

Title: “Probability in Quantum Mechanics”

Speaker: Mark Srednicki (University of California, Santa Barbara)

Venue & Time: Red Room / 15:00

Abstract: This year marks the 100th anniversary of the Born rule for probabilities of outcomes of measurements on quantum systems, but there is still no generally accepted understanding of its status. One reason for this lack of consensus is that there are several inequivalent conceptions of probability itself, and any proposed derivation of the Born rule depends on which one is adopted. The key question for physics is whether or not a “collapse postulate” is needed, or whether, as originally proposed by Everett, unitary time evolution of a quantum state of the universe is consistent with observation, including the Born rule. I will argue that it is, and that the appropriate conception of probability is the original one of Laplace. The “decoherent histories” formalism of Gell-Mann and Hartle provides the necessary mathematical structure.