Weyl on good and evil

Hermann Weyl once said “In these days the angel of topology and the devil of abstract algebra fight for the soul of every individual discipline of mathematics.” Discuss.

Vakil on Gromov-Witten Theory

One of the stranger developments of recent years is the influence of physics on algebraic geometry. A dramatic recent example is Gromov-Witten theory, which draws its inspiration from quantum field theory, but can be used to study the moduli space of complex algebraic curves.

A moduli space is a space that parameterizes all objects of a certain type. The classic example is the projective line, which classifies lines in the plane: each line in the plane corresponds to one and only one point in the plane. The moduli space of curves classifies complex-algebraic curves. The space itself is a geometric object, but its structure turns out to be very complicated, and recent progress has relied on these ideas from physics.

Ravi Vakil has posted a survey article on the subject, The moduli space of curves and Gromov-Witten theory, to Arxiv. He also has an older, more elementary article from the June/July 2003 Notices of the AMS, The moduli space of curves and its tautological ring.

Colbert Report and Spam

According to Steven Colbert on tonight’s Colbert Report, equations are the devil’s sentences. For the past couple of days, this site has been under relentless spam attack (the spam has been showing up in older posts, so no one sees them but me). Clearly, these two events are related.

Flyspeck Project

Via Neighborhood of Infinity, I came across the Flyspeck Project, a project to provide a computer-checked proof of the Kepler conjecture.

The project who proposed by Thomas Hales, who has the only published proof of the theorem. His proof already includes some computer calculations, and turned out to be too complicated to be fully checked by peer review. A complete computer-checked proof would remove any doubts.

The Wikipedia entry links to this elementary introduction by Hales to the proof, Cannonballs and Honeycomb.