I got back a couple days ago from John Preskill‘s 60th birthday symposium at Caltech. To the general public, Preskill is probably best known for winning two bets against Stephen Hawking. To readers of Shtetl-Optimized, he might be known for his leadership in quantum information science, his pioneering work in quantum error-correction, his beautiful lecture notes, or even his occasional comments here (though these days he has his own group blog and Twitter feed to keep him busy). I know John as a friend, colleague, and mentor who’s done more for me than I can say.
The symposium was a blast—a chance to hear phenomenal talks, enjoy the California sun, and catch up with old friends like Dave Bacon (who stepped down as Pontiff before stepping down as Pontiff was cool). The only bad part was that I inadvertently insulted John in my talk, by calling him my “lodestar of sanity.” What I meant was that, for 13 years, I’ve known plenty of physicists who can be arbitrarily off-base when they talk about computer science and vice versa, but I’ve only ever known John to be on-base about either. If you asked him a question involving, say, both Barrington’s Theorem and Majorana fermions, he’s one of the few people on earth who would know both, seem totally unfazed by your juxtaposing them, and probably have an answer that he’d carefully tailor to your level of knowledge and interest. In a polyglot field like quantum information, that alone makes him invaluable. But along with his penetrating insight comes enviable judgment and felicity of expression: unlike some of us (me), John always manages to tell the truth without offending his listeners. If I were somehow entrusted with choosing a President of the United States, he’d be one of my first choices, certainly ahead of myself.
Anyway, it turned out that John didn’t like my use of the word “sane” to summarize the above: for him (understandably, in retrospect), it had connotations of being humorless and boring, two qualities I’ve never seen in him. (Also, as I pointed out later, the amount of time John has spent helping me and patiently explaining stuff to me does weigh heavily against his sanity.) So I hereby rename John my Lodestar of Awesomeness.
In case anyone cares, my talk was entitled “Hidden Variables as Fruitful Dead Ends”; the PowerPoint slides are here. I spoke about a new preprint by Adam Bouland, Lynn Chua, George Lowther, and myself, on possibility and impossibility results for “ψ-epistemic theories” (a class of hidden-variable theories that was also the subject of the recent PBR Theorem, discussed previously on this blog). My talk also included material from my old paper Quantum Computing and Hidden Variables.
The complete program is here. A few highlights (feel free to mention others in the comments):
- Patrick Hayden spoke about a beautiful result of himself and Alex May, on “where and when a qubit can be.” After the talk, I commented that it’s lucky for the sake of Hayden and May’s induction proof that 3 happens to be the next integer after 2. If you get that joke, then I think you’ll understand their result and vice versa.
- Lenny Susskind—whose bestselling The Theoretical Minimum is on my to-read list—spoke about his views on the AMPS firewall argument. As you know if you’ve been reading physics blogs, the firewall argument has been burning up (har, har) the world of quantum gravity for months, putting up for grabs aspects of black hole physics long considered settled (or not, depending on who you ask). Lenny gave a typically-masterful summary, which for the first time enabled me to understand the role played in the AMPS argument by “the Zone” (a region near the black hole but outside its event horizon, in which the Hawking radiation behaves a little differently than it does when it’s further away). I was particularly struck by Lenny’s comment that whether an observer falling into a black hole encounters a firewall might be “physics’ Axiom of Choice”: that is, we can only follow the logical consequences of theories we formulate outside black-hole event horizons, and maybe those theories simply don’t decide the firewall question one way or the other. (Then again, maybe they do.) Lenny also briefly mentioned a striking recent paper by Harlow and Hayden, which argues that the true resolution of the AMPS paradox might involve … wait for it … computational complexity, and specifically, the difficulty of solving QSZK (Quantum Statistical Zero Knowledge) problems in BQP. And what’s a main piece evidence that QSZK⊄BQP? Why, the collision lower bound, which I proved 12 years ago while a summer student at Caltech and an awestruck attendee of Preskill’s weekly group meetings. Good thing no one told me back then that black holes were involved.
- Charlie Bennett talked about things that I’ve never had the courage to give a talk about, like the Doomsday Argument and the Fermi Paradox. But his disarming, avuncular manner made it all seem less crazy than it was.
- Paul Ginsparg, founder of the arXiv, presented the results of a stylometric analysis of John Preskill’s and Alexei Kitaev’s research papers. The main results were as follows: (1) John and Alexei are easily distinguishable from each other, due in part to the more latter’s “Russian” use of function words (“the,” “which,” “that,” etc.). (2) Alexei, despite having lived in the US for more than a decade, is if anything becoming more “Russian” in his function word use over time. (3) Even more interestingly, John is also becoming more “Russian” in his function word use—a possible result of his long interaction with Alexei. (4) A joint paper by Kitaev and Preskill was indeed written by both of them. (Update: While detained at the airport, Paul decided to post an online video of his talk.)
Speaking of which, the great Alexei Kitaev himself—the $3 million man—spoke about Berry curvature for many-body systems, but unfortunately I had to fly back early (y’know, 2-month-old baby) and missed his talk. Maybe someone else can provide a summary.
Happy 60th birthday, John!
Two unrelated announcements.
1. Everyone who reads this blog should buy Sean Carroll’s two recent books: From Eternity to Here (about the arrow of time) and The Particle at the End of the Universe (about the Higgs boson and quantum field theory more generally). They’re two of the best popular physics books I’ve ever read—in their honesty, humor, clarity, and total lack of pretense, they exemplify what every book in this genre should be but very few are. If you need even more inducement, go watch Sean hit it out of the park on the Colbert Report (and then do it again). I can’t watch those videos without seething with jealousy: given how many “OK”s and “y’know”s lard my every spoken utterance, I’ll probably never get invited to hawk a book on Colbert. Which is a shame, because as it happens, my Quantum Computing Since Democritus book will finally be released in the US by Cambridge University Press on April 30th! (It’s already available in the UK, but apparently needs to be shipped to the US by boat.) And it’s loaded with new material, not contained in the online lecture notes. And you can preorder it now. And my hawking of Sean’s books is in no way whatsoever related to any hope that Sean might return the favor with my book.
2. Recent Turing Award winner Silvio Micali asks me to advertise the Second Cambridge Area Economics and Computation Day (CAEC’13), which will be held on Friday April 26 at MIT. Anything for you, Silvio! (At least for the next week or two.)