Highlights from lunch, February 2019

A fun fact about how solutions to the wave equation behaves very differently in even dimensions: in 2 dimensions, instead of a single clap, you'll hear a decaying tail of claps. Because, somehow, to do the analysis you have to imagine going up a dimension and replacing your point source with a one-dimensional source. Sound travels from all along that line towards you, with suitable delays and decay ... hence that decaying tail ...since Pac-man eats stuff on a plane, you shouldn't just hear a "piu" every time he eats something, it should be more like "PIIUUuuuu ... "

Stark as daylight, luminous and harsh in equal measure

 Truly, ignorance is bliss ... but at what price ...

Still a little too real

We live in capitalism, its power seems inescapable —

but then, so did the divine right of kings. Any human power can be resisted and changed by human beings.

--- Ursula K. Le Guin 

Hehehe

(from Bob Fitch Photography Archive, via PAW) 

Lest I forget

What happened on June 4th 1989 was wrong. To deny it will only let the wounds fester and the body politic rot further. 

What has been happening in the western periphery in the past decade is wrong and deeply counterproductive. They may buy you a brittle and superficial quiet, but there can be no true and lasting peace without justice.

What you have been doing in the supposedly autonomous southern territories this past year or two is wrong and similarly misguided. 

I hope you fail miserably, and I will do everything in my power to work against your misguided actions, because they are utterly abhorrent to me, and I will not have it on my conscience to be part of a nation that does such stupid and hurtful things. 

 一个健康的社会不该只有一种声音

A glorious decade

10 years ago to the day I flew into JFK and took a 2-3 hour shuttle ride to Princeton. I was wide-eyed, maybe a little cynical, mostly naive and inexperienced.

Last week I drove 10 hours, in a rental car, from Ann Arbor to JFK and flew out to Israel. With much more baggage, in every sense of the word. Baggage weighs us down (all glorious 200 pounds of it---oh boy does some of that have to go), but it also contains all manner of useful and joyful things. I may still be cynical and naive and wide-eyed, but only (I hope) in the best sense. 

10 years in the US have taught and given me a lot. I hope to be back soon.

Take a deep breath and repeat after me

1. While starving yourself of information would be foolhardy, bingeing on a firehose of information is neither conducive to your sanity and happiness, nor helpful for good decision-making. Systematically avoid both extremes. Adopt blunt measures to achieve this if need be.
2. Life goes on. Things will change, for better or for worse. There will be hardships that we will all have to bear, some more than others. But life will go on. 
3. Don't ignore the world around you, but don't let it consume you. Focus on the here and now. In particular: there are things you were going to do, that still need to be done, and that you have the time and space to do now. Do them.
4. It's unfortunate that these words have been coopted for other, more propagandistic purposes, but remember: 群防群治

... yön uhka karkoitettu on jo pois,

ja aamun kiuru kirkkaudessa soittaa ...

(Was this really written in the middle of WWII? I guess maybe it was after the Winter War ... )

Three reactions, or: ideology as jargon

I
I don't know how I feel about that statement about the goal of that part of the contract being to fight against "white supremacy" or "imperialism". Partly I'm not convinced most of the people who make such statements really know what they are talking about when they say "imperialism". I'm also just not convinced that it's meaningful to talk about those broad abstract terms other as useful frames for analysis. In terms of actual changes we want to see in the world, it seems much more useful to me to articulate these in concrete terms, and to articulate the rationales in similarly concrete terms: who is being harmed, and how, and how do we propose to address that? Articulate that in plain language, not all adorned in fancy ideological garb. Even if I am partial to some of that ideological garb, I don't know that it serves any useful purpose here, beyond possibly a purely tribal one of pulling together all the other people who are partial to that garb.
II
Maybe white supremacy, or some sort of imperialism, broadly but not so broadly construed, does constitute the substantive background to the issues we are fighting over. But it still seems to me not so useful to just name-drop that, unless you have concrete, compelling ways of tying in that background to the issues at hand. Otherwise all that would do is trigger the anti-SJW anti-PC right-wing types without adding anything truly substantive to the fight.
III
Also I'm still not convinced you really know what you talking about. If you are, you should be able to break it down into concrete, specific terms. To some extent this annoyance I'm feeling is of a piece with the annoyance I feel towards people who spout jargon like "motivic integration over formal stacks" without ever bothering to explain what the hell that means and why they (or anyone else) should care about it.

That's a rather mild translation, innit

"Death to tyrants" would have been a feistier but still accurate rendition.

Mladen could probably've told ya

I had a dream in honor of my late friend and co-author Gilbert Baumslag. Gilbert and I were both in Berkeley, and he invited me to come over for lunch in the free product with amalgamation that he was renting. It was not clear which factor I was supposed to come to, and figuring this out involved some tricky group theory. I was still puzzled about it when I woke up.

Peter Shalen, via Facebook

Meh fact of the day

"Meh" might come from the Yiddish, via the Simpsons. From the Oxford English Dictionary:

Etymology: Probably <  Yiddish me be it as it may, so-so (1928 or earlier), probably imitative.
Probably popularized by the U.S. cartoon series The Simpsons , in which its earliest use was in the episode Sideshow Bob Roberts , first broadcast on 9 Oct. 1994.

A RAAG, an Anosov representation, and a Higgs bundle walk into a bar.

They start debating what GEAR could stand for. They immediately reject the notion that it could possibly stand for "Geometric structures and representation varieties", noting that this goes against everything that acronyms are supposed to do. After some back-and-forth the right-angled Artin group proposes that the acronym captures the way that the network functions: "Guesses, Errors And Retries". The Anosov representation and the Higgs bundle don't like this very much ... after more debate, the Anosov representation claims that the acronym is all about the guiding principle of the network: "Give Everybody Ample Renumeration". This is not universally accepted either, and the argument goes on ... finally, the Higgs bundle comes up with what is obviously the most perfect answer ... but nobody can understand a word of it.

(from Steve Bradlow, at the GEAR retreat banquet)

I am sorry for your loss.

I am sorry for our loss.
Let us do our best to honour her wonderful legacy.

Meanwhile, in math grad school

My sentiments exactly

Grad school in 2017: an absolute riot.

Gloom, schmoom

The storm clouds may be gathering

But blithely shall we fly by them

And soar as we always have

Surely and swiftly through even the darkest night

2017 January 4-7, Singapore and Ann Arbor (i.e. home and home)

Danke schön Österreich

Now we can keep going for a little longer.