Emma and Jacob each share half my DNA. After that, it is strange how little kin I’ve got. Third-closest is Cousin Nancy, whose mother and my grandmother were sisters and whose father and my grandfather were (I think) first cousins. So Nancy and I share 5/64 of a genome. Just a neck behind her are Ted, Ron, and Bruce Harrington, whose father was my father’s half-brother. That’s 1/16 of a genome each. After them, I think everybody is at the 1/32 level or below. My overlap with John Trefethen, Chairman of Trefethen Vineyards and my sixth cousin, is unfortunately just 1/8192.

# Author: nicktrefethen

# Co-working with a blackbird

For the past two months I have sat at my desk doing mathematics, while on the lawn out the window, a blackbird has been hopping about finding worms. He’s there in the morning and he’s there at noon and he’s there in the evening. He hops, he stops, he hops again. All day long.

I remarked to Kate, what an empty and meaningless life he leads! She countered that the blackbird probably thinks my life is meaningless too.

So I have refined my view, appreciating my good fortune to be sharing this confinement with such an agreeable colleague.

[25 May 2020]

# You could knit a sweater by the fireside

I updated my profile on italki, including date of birth, and I ticked the box “Allow people to view my age.” Why not?

Then I checked how my profile appeared online and I was horrified. My age was showing as 65! Why, I’m only 64, not 65, and I won’t be 65 until August! What a blunder of programming! How deeply they had got me wrong!

I immediately went back and unticked the box.

[11 April 2020]

# Chopping an onion during COVID-19

The pandemic so consumes us that everything exists in reference to the big story. As I chopped an onion for dinner, my eyes started burning. Instantly I realized this was a model of how virus particles can undetected reach our face.

[11 April 2020]

# Three plagues this millennium at Balliol

Today for the first time ever, because of the coronavirus pandemic, Balliol’s Governing Body meeting was held online. We didn’t do this in 1348 (Black Death) or 1665 (Great Plague).

[16 March 2020]

# Mathematicians, too, are distracted by mathematics

A colleague tells me that among students and faculty in economics these days, it’s hard to find people who are genuinely interested in how economies work. Instead they are wrapped up in the technicalities of the mathematical models they have been trained to analyze. Give the students an exam question that requires thought about fundamentals, he tells me, and rather little comes back.

It’s the same in mathematics! It may sound paradoxical, but here, too, students and researchers are distracted, and excessively impressed, by mathematical technicalities. Give the students an exam question that requires thought about what the *point* of a mathematical construction is and — I speak from long experience — they will hurry off in search of more technical questions, where they can turn the crank.

One might have thought that mathematics would be the one field immune to the problem of being dazzled by mathematics. But in fact, it’s just as bad here as elsewhere, maybe worse, since camouflaged.

[11 March 2020]

# Maths, physics, and Jean Perrin

Often physicists do something new, and mathematicians later make it rigorous. Generally the physicists couldn’t care less, and as for the mathematicians, they quickly forget the physicists’ part in the story.

Here’s an example in the beloved book by Körner on Fourier series. In 1909 the physicist Jean Perrin, building on Einstein’s paper of 1905, realized that Brownian motion trajectories are continuous but nowhere differentiable. This was made mathematically rigorous in the 1920s by Norbert Wiener and Paul Levy. Körner summarizes Wiener’s construction with the words, “In accordance with Perrin’s prophetic remarks [the Brownian paths] turned out to be continuous and nowhere differentiable”.

Prophetic remarks! Once again, it would seem, a physicist had struck it lucky.

[8 March 2020]