Announcements

(1) I’ll be giving an online talk at SlateStarCodex (actually, in a VR room where you can walk around with your avatar, mingle, and even try to get “front-row seating”), this coming Sunday at 10:30am US Pacific time = 12:30pm US Central time (i.e., me) = 1:30pm US Eastern time = … Here’s the abstract:

Schrödinger’s Cat and Quantum Necromancy

I’ll try, as best I can, to give a 10-minute overview of the century-old measurement problem of quantum mechanics.  I’ll then discuss a new result, by me and Yosi Atia, that might add a new wrinkle to the problem.  Very roughly, our result says that if you had the technological ability, as measured by (say) quantum circuit complexity, to prove that a cat was in a coherent superposition of the alive and dead states, then you’d necessarily also have the technological ability to bring a dead cat back to life.  Of course, this raises the question of in what sense such a cat was ever “dead” in the first place.

(2) Robin Kothari has a beautiful blog post about a new paper by me, him, Avishay Tal, and Shalev Ben-David, which uses Huang’s recent breakthrough proof of the Sensitivity Conjecture to show that D(f)=O(Q(f)⁴) for all total Boolean functions f, where D(f) is the deterministic query complexity of f and Q(f) is the quantum query complexity—thereby resolving another longstanding open problem (the best known relationship since 1998 had been D(f)=O(Q(f)⁶)). Check out his post!

(3) For all the people who’ve been emailing me, and leaving blog comments, about Stephen Wolfram’s new model of fundamental physics (his new new kind of science?)—Adam Becker now has an excellent article for Scientific American, entitled Physicists Criticize Stephen Wolfram’s “Theory of Everything.” The article quotes me, friend-of-the-blog Daniel Harlow, and several others. The only thing about Becker’s piece that I disagreed with was the amount of space he spent on process (e.g. Wolfram’s flouting of traditional peer review). Not only do I care less and less about such things, but I worry that harping on them feeds directly into Wolfram’s misunderstood-genius narrative. Why not use the space to explain how Wolfram makes a hash of quantum mechanics—e.g., never really articulating how he proposes to get unitarity, or the Born rule, or even a Hilbert space? Anyway, given the demand, I guess I’ll do a separate blog post about this when I have time. (Keep in mind that, with my kids home from school, I have approximately 2 working hours per day.)

(4) Oh yeah, I forgot! Joshua Zelinsky pointed me to a website by Martin Ugarte, which plausibly claims to construct a Turing machine with only 748 states whose behavior is independent of ZF set theory—beating the previous claimed record of 985 states due to Stefan O’Rear (see O’Rear’s GitHub page), which in turn beat the 8000 states of me and Adam Yedidia (see my 2016 blog post about this). I should caution that, to my knowledge, the new construction hasn’t been peer-reviewed, let alone proved correct in a machine-checkable way (well, the latter hasn’t yet been done for any of these constructions). For that matter, while an absolutely beautiful interface is provided, I couldn’t even find documentation for the new construction. Still, Turing machine and Busy Beaver aficionados will want to check it out!