The Logos Scripture · The Book of Yang Chen-Ning

On Finding That What I Made Had Been Made Already

The Book of Yang Chen-Ning 3 · Written by himself, from the paper of 1956, the commentary on his own work of 1983, and his writings on beauty

Yang Chen-Ning, born at Hefei in Anhui in China in 1922, died at Beijing in 2025, aged 103. Physicist. His father taught mathematics at Tsinghua and he grew up on that campus. In 1956, with Lee Tsung-Dao, he wrote a paper titled Question of Parity Conservation in Weak Interactions, showing that the law had never been tested for the weak force and setting out experiments that would test it; the next year Wu Chien-Shiung and others carried one out, and it was confirmed. In 1957 the two of them took the Nobel in physics together, the first Chinese to receive it — what chapter one describes is work the two did together, and the Order does not assign it to one of them. In 1954, with Mills, he wrote the paper that begins what is now called gauge field theory; there was a point in it that did not work, which the two stated plainly and published anyway, and twenty years later it became the frame of particle physics. In 1975, with Wu Tai Tsun, he drew up a table setting the physicists names against the mathematicians one for one. This volume rests on what he wrote or delivered himself: the paper of 1956; the long commentary he wrote in 1983 on his own earlier work, in which he sets down what he had thought and where he had been wrong (chapter two is taken from it); and his writings on beauty and physics. On God: he said that if what you ask after is a god in the shape of a man, he thinks there is none; that if you ask whether there is a maker, he thinks there is, because the structure of the whole world is not accidental. He also said that if the name carries no human shape in it, everyone can accept it, and he stated of himself that in his youth he had firmly opposed giving the maker or nature a human figure, and that as he aged his force of opposition weakened. The Order records this as he put it and does not tidy it for him. What matters is this: the word in his mouth is a name for the structure, not a step in an argument. No argument of his closes on divine will. What this volume brings is something the scripture did not have: beauty. There are books here that say to study for beauty (cf. The Book of Marie Curie 3.11) and that understanding takes nothing from beauty (cf. The Book of Feynman 2); none has asked whether beauty, which so often leads right, counts as a warrant. He stood on both sides of that question: once beauty deceived a whole generation, and once it carried him right when he could give no reason, and both times he could not tell which. He gave no answer, and the Order does not supply one for him. The last verse of chapter four is all he had.

3.1Around 1970 I was at Stony Brook, next door to a mathematician. From him I heard of a branch of mathematics called fibre bundles.
3.2The more I listened the stranger I felt, because I knew the things he was describing.
3.3They were what I had built for physics more than ten years before, matching item for item.
3.4What we called a gauge, they called a principal coordinate bundle; what we called a potential, they called a connection. The names differed and the thing was the same thing.
3.5Wu Tai Tsun and I set the two sets of names out in a table, line against line. When the table was done I sat there a good while.
3.6We built ours in order to calculate something in physics.
3.7They built theirs to calculate nothing. They built it for mathematics itself, earlier than we did, and without knowing we existed.
3.8In 1975 I told this to Chern Shiing-Shen.
3.9I said: this is both thrilling and puzzling, because you mathematicians dreamed these concepts up out of nowhere.
3.10He would not have it. He said at once: no, no, these concepts were not dreamed up. They were natural and real.
3.11That sentence of his I have thought about for many years.
3.12What he meant was that they had invented nothing. They had walked over a certain country, seeing the roads as they went, and had written the roads down.
3.13And I had walked over another country and come out on the same road.
3.14When two men who are not in touch walk separately and come out on the same road, that road was most likely not laid by either of them.
3.15Mathematics is thought out by men sitting in a room; it does not look outside. And yet the things outside are very often exactly the shape of what was thought out in the room. I do not know why.
3.16Some say the mind and the world outside grew up along one line. Some say it is chance, and that you remember only the matches and not the misses. Neither answer sounds like enough to me.
3.17I set the matter down here and hand it on. When you cannot answer a thing, you can at least ask it exactly, and not let it be fudged.
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