Yeshiva

Yeshiva's customs are strange. They separately teach men and women in different campuses, yet Naomi tells me of 'mixing events'. How else to produce the next generation? The Beren campus for women in Manhattan housed the first Blackboard Lectures in physics, organized by Emil. Blackboard is good, it's so much easier to prepare a presentation. I talked about Wilson loops and inversion-symmetric topological insulators, my first project and one of my pet loves. In my preparation, I divided the 30-minute presentation into three segments: 1D  in the first 12 min, some 2D in the next 12, and the relative winding number in the last 6. I was really excited to get to the relative winding, which was a recent baby of mine, so it deserved its own segment.  In practice, I stopped at the first mark, in 29 minutes 58 seconds, as Bo claims. It was a blitz, I talked fast, wrote fast, derived fast (the relation between Wilson and Wannier), but not fast enough. I had to wonder why my definition of unitary is not strictly correct, and why the hell a Wilson line is instead isometric. Pity about the relative winding. Emil got up and told the audience that 'this is what the Blackboard lectures are about, an exchange of information between audience and lecturer; the presentation was very good.' Later, he came up to me and gave me a fatherly pat, saying once again, 'Very good.' Shinshei, whose work I admire from afar, admitted to me that he had tried to derive the tight-binding Wilson loop, but failed. He also told me that he thought of the Z classification in the entanglement spectrum, which surprised me because I thought our group and Ashvin's were the only two. As Kundera writes, many many people, few original gestures. With some satisfaction, I told him that the two formulations coincide. Overall, I am feeling 'very good' about the whole matter, even as I'm typing this in the Starbucks outside my international hostel.

Alexey is going to ETH in Switzerland. We talked deeply into the evening, before he hurried off, saying he didn't want to anger a girl. When prodded, I found out he has a Russian mistress. I really like this guy, and he gave me the idea of an inversion pump.