Richard Borcherds

"(quote at 35:35 of 1:36:06 in video)"

"... if you take the s, we have a classification of them ... And then weve got a very simple explanation of why this list turns up, that they more or less correspond to finite reflection groups. And we know who to classify finite reflection groups. ... we can give single uniform construction of all the compact Lie groups. But theres nothing like that for the sporadic groups."

"The classification of s shows that every finite simple group either fits into one of about 20 infinite families, or is one of 26 exceptions, called . The is the largest of the sporadic finite simple groups, and was discovered by and ... Its order is 8080,17424,79451,28758,86459,90496,17107,57005,75436,80000,00000 = 246 ⋅ 320 ⋅ 59 ⋅ 76 ⋅ 112 ⋅ 133 ⋅ 17 ⋅ 19 ⋅ 23 ⋅29 ⋅ 31 ⋅ 41 ⋅ 47 ⋅ 59 ⋅ 71 (which is roughly the number of elementary particles in the earth). The smallest irreducible representations have dimensions 1, 196883, 21296876, ... The has the power series expansion j(τ) = q−1 + 744 + 196884q + 21493760q2 +... where q = e2π iτ, and is in some sense the simplest nonconstant function satisfying the functional equations j(τ) = j(τ + 1) = j(−1/τ). noticed some rather weird relations between coefficients of the elliptic modular function and the representations of the monster as follows: 1 = 1 196884 = 196883 + 1 21493760 = 21296876 + 196883 + 1 where the numbers on the left are coefficients of j(τ) and the numbers on the right are dimensions of irreducible representations of the monster. At the time he discovered these relations, several people thought it so unlikely that there could be a relation between the monster and the elliptic modular function that they politely told McKay that he was talking nonsense. The term “monstrous moonshine” (coined by ) refers to various extensions of McKay’s observation, and in particular to relations between sporadic simple groups and modular functions."