Theoretical Physics Seminar: Yasha Neiman

This is the 28th biweekly session of the OIST Theoretical Physics Seminar.
In this seminar series, we pretend to have a theoretical physics department, and tell each other informal stories over drinks and snacks.
Except no drinks and snacks, because people stopped consuming them for some reason. If you want them back, let me know.

Speaker: Yasha Neiman (Quantum Gravity).
Title: "Quantum mechanics without probabilities".

I always had a feeling that there's something spooky about quantum-mechanical probabilities and the Born rule. After reading Sidney Coleman's lecture on the matter (arXiv:2011.12671), I now feel much better, and I'd like to share that feeling. In particular, I think I can make sense of QM's predictions without invoking any probabilities other than 0 and 1 (naturally, this type of exorcism will apply to classical probabilities as well). In the process, I will also clear up a confusion that I had about the S-matrix of massless particles. I will then formulate a new, sharper confusion about the S-matrix's soft/IR part.