It’s been a while since the last posting here, mostly because I’ve been away on vacation, but also because I haven’t seen anything that newsworthy. But, since I’m back in the office and there have been complaints, here are a few items:

- For the first time in a very large number of years, a new volume has appeared in the series of Bourbaki treatises, dealing with algebraic topology (table of contents here). From the table of contents, it appears to be a rather modern treatment mostly of the fundamental group, but still in the Bourbaki style of exhaustive coverage and abstract point of view (I don’t see any mention there of actually computing the fundamental group of anything…).
- While in Paris I attended some of the Seminaire Bourbaki talks. You too can watch via Youtube, or read the written versions.
- Far from mathematics and physics, one thing I did in Paris was stop by a store selling Breton products, and had a discussion with the owner about Kouign Amanns. He had a short hand-written list of a few places they could be had in the US. When I got back here, the next morning I went out to my local bakery (Silver Moon, at Broadway and 105th), and found that while I was away they had started selling them.
- On the Mochizuki front, there’s a new paper by Vesselin Dimitrov, claiming that if Mochizuki’s argument is correct, it implies something even stronger than Mochizuki claims, an effective version of the abc conjecture. The next workshop about this will be in Kyoto in July. One mathematician who has gotten interested in this and is listed as planning to attend is Edward Frenkel.
- If you can’t get enough of the “Is HEP physics dead or what?” debate, see John Horgan on How Physics Lost its Fizz.
- Among the things going on here at Columbia this semester, there are Eilenberg Lectures on geometric representation theory (starting in a few minutes…) by Roman Bezrukavnikov, a course by Michael Harris on Lafforgue’s recent work on the Langlands correspondence for function fields (also the topic of one of the Seminaire Bourbaki talks), and a conference celebrating Dusa McDuff’s 70th birthday.

Better leave now to get a seat at the talk…

Kouign-amanns are fairly common now at San Francisco bakeries and coffee shops, and yes they are delicious.

Ronnie Brown would be happy that the van Kampen theorem is proved for fundamental groupoids and not just for groups, and has a thorough treatment of groupoids generally.

Bryan…Multiple layers of sweet resplendency.

I see that Trader Joe’s sells frozen pack of four that you have to proof before baking. Has anyone tried those?

What is your take on the big rumor that GW’s were found at the advanced LIGO run?

John,

I know nothing about that rumor. That advanced LIGO sees something has always been the expectation, so a detection would in some sense not be surprising (although a great breakthrough in opening up a new kind of astronomy).

As for whether putting out the rumor on Twitter was a good idea, my own prejudice is that one should only put out rumors that one has a very good reason to believe, at a point where there’s no good argument for keeping information secret. I think the history of rumors about LHC results so far has been that they’ve been pretty accurate, something that those in other fields should try and emulate…

“Kouign-amann is a speciality of the town Douarnenez in Finistère, Brittany, where it originated in around 1860. The strict recipe of Douarnenez requires a ratio of 40 percent dough, 30 percent butter and 30 percent sugar.”

Solid fare for the morning, indeed.

John,

it’s known that LIGO people sometimes deliberately put in fake signals and only reveal it when the publication announcing the discovery is about to be submitted. It’s called “blind injection”, and they do this as a test of the detection procedures: http://www.ligo.org/news/blind-injection.php

Slide 16 of Carlo Rovelli’s talk is worth using as a banner on this website:

https://videoonline.edu.lmu.de/en/node/7477