Paul Johnson

@ptwiddle.bsky.social

329 Followers 635 Following

American mathematician in the UK. Mellowing in middle age. He/Him.

Plaque on a pavement, saying "Adela Pankhurst suffragette lived here 1910-1911"
Cardamom knot on a plate with a bite out, a few bags in the background with a chocolate croissant visible
A hand holding up a set of Borromean rings made from paper
An 8 by 8 grid of partitions into distinct parts. No explanation given.
Road side saying there's a continental divide; but it's the middle of a flat green field and not the "expected" mountain.
Two bsky posts from mathematicians, doing the "5 courses you took as an undergrad" meme, with the first four of each being mostly liberal arts courses and the last one being differential geometry.
Grey high rise hospital on a grey day. One window has pink and blue colour frames and yellow and green blocks of colour
View of an urban sunset. Children's hospital with lots of bright lights in foreground
A paragraph from Jackie Ess's Darryl: Satori is such a perfect woman that she makes a man even out of me. I am a man. But my manhood is like a hothouse flower, not of our climate. Delicate, but real. I feel strong. There's a Bob Dylan song where he says, "Take a woman like your kind to find the man in me.' So is 'your kind' a slightly hippie goth aesthetic in a spiritually realized poly chick? He probably meant a different kinda I think that's why the song works though, it's nothing to do with types. But the song totally inhabits a moment, the guy singing it does t know that yet. I never really liked Bob Dylan, it always felt like he was lecturing me or trying to get me to be a Christian or something, but I heard that song in a movie once, and it made me go back to his stuff.
Squirrel sprawled out on its belly in the sun at the peak of a tiled roof.
Messy handwritten proof using similar triangles
Picture of an official looking sign saying "PEDESTRIANS GOOD LUCK" attached to a lamppost in front of a busy intersection.
Picture of the 15th pentagonal tiling, white lines on black paper)
Bowl of rice porridge with cilantro, pumpkin seeds, and green onion on top, next to some broccoli on a plate.
Two books on a table. Black Paper by Teju Cole, and Toward Eternity by Anton Hur.
Snipper from Culler and Vogtmann's Moduli of Graphs and Automorphisms of Free Groups. Starting in Section 1.3 Roses, it states the Gertrude Stein Lemma.
This question brings to the fore something that is fundamental and pervasive: that what we are doing is finding ways for people to understand and think about mathematics. The rapid advance of computers has helped dramatize this point, because computers and people are very different. For instance, when Appel and Haken completed a proof of the 4-color map theorem using a massive automatic computation, it evoked much controversy. I interpret the controversy as having little to do with doubt people had as to the veracity of the theorem or the correctness of the proof. Rather, it reflected a continuing desire for human understanding of a proof, in addition to knowledge that the theorem is true. On a more everyday level, it is common for people first starting to grapple with computers to make large-scale computations of things they might have done on a smaller scale by hand. They might print out a table of the first 10,000 primes, only to find that their printout isn’t something they really wanted after all. They discover by this kind of experience that what they really want is usually not some collection of “answers”—what they want is understanding.
Selfie of bearded man (me!) in running gear, holding a paper espresso cup, in front of small green van with "Motore Cafe" written on it. Nether Edge market, Sheffield.
A hand holding a copy of the Borromean Rings made out of wood: three loops so that are interlocked in such a way that they can't be separated, but if any one loop was removed, the other two could be separated.
View at a football match. Looking over the shoulder of a young girl as she reads a novel, green of the pitch, bright lights and the crowd in the background.
A stone staircase outside, turned into a waterfall.
View over a snow covered valley.
Blurry shot of snow falling in streetlight in front of stone building
Not a birb, but a bat -- a child in a narrow brick alley trick or treating in a bat costume.
Weston Park in Sheffield. Modernist building Arts Tower in the background, teal bandstand, one large tree with just a few leaves hanging on still and a carpet of them spread beneath.
Trees and power lines in silhouette against a grey-blue dusk sky.