# Colloquium: “Collapse of the Collapse: Physicists Return to Reality” — December 2, 2021 at 4 PM

Murray Daw, Ph.D.

Dean’s Distinguished Professor

Physics and Astronomy

Clemson University

Clemson, SC

Thursday, December 2, 2021, 4 PM

George P. Williams, Jr. Lecture Hall, (Olin 101)

Video Link will be available if needed

To obtain the video conference link, contact wfuphys@wfu.edu

Welcome Back to in-person Colloquiums!

A reception will be held in Olin Lounge* at 3:30 PM prior to the colloquium. All interested persons are cordially invited to attend.

* We encourage all to wander out to the front entrance of the building or up to the Observatory Deck on the 3rd floor to enjoy their refreshments.

ABSTRACT

We note the recent demise[1] of the collapse hypothesis, that an integral part of quantum mechanics is the “collapse” of the state of a system when measured. Using recent work of Anthony Rizzi, we show that the Ensemble Interpretation provides a simple and natural resolution to the problem of measurement[2,3] in quantum mechanics. Along the way, we give a fuller explanation of the Ensemble Interpretation[4] (in spite of the familiar-sounding name, this is almost entirely unknown), measurement theory in general (correcting many common misconceptions), the resolution of the Schrodinger Cat experiment, Wigner’s Friend experiment, and the Extended Wigner’s Friend experiment. At the end we encourage discussion of how to deal with the pedagogical situation, given that almost all current QM textbooks[5] are based on the (now defunct) collapse hypothesis.

[1] D. Frauchiger & R. Renner, “Quantum theory cannot consistently describe the use of itself”, Nature Comm. [2018]

[2] A. Rizzi, “How the natural interpretation of QM avoids the recent no-go theorem” [Foundations of Physics, 2020]

[3] A. Rizzi, “A simple approach to measurement in quantum mechanics”, arXiv [2020]

[4] See, for example, two textbooks: L. Ballentine, “Quantum Mechanics”, and A. Rizzi, “Physics for Realists: Quantum Mechanics”.

[5] Two examples used at Clemson include Griffiths and Morrison.

Reference Material:

https://sites.google.com/g.clemson.edu/qmcollapse

Professional Website:

https://www.clemson.edu/science/departments/physics-astro/people/profiles/daw