Here is an ugly truth: back in 1970, when I heard the news about the Kent State killings, I felt smug.

I was fifteen years old. I was Canadian. It pleased me in a spiteful way that the U.S. had so blatantly screwed up.

I was fifteen. I was self-righteous. I had never been to a funeral.

The vectors that flip-flop in the ergosphere indicate symmetries in the gravitational field. One vector is timelike; it indicates that the laws of gravity don’t change over time. The other vector is space-like; it describes the rotational symmetry of the black hole.

These vectors are called Killing vectors. Really. They’re named after a Professor Wilhelm K. J. Killing of the University of Mьnster. He gave his name to such geometrical objects in 1892, many decades before Kerr and Newman used them in their model of a rotating black hole.

Killing vectors.

May 4, 1990, was a Friday, but all the local newspapers saved their Kent State retrospectives for the weekend editions. I bought three papers that Saturday — the Globe & Mail for its book reviews, the Kitchener-Waterloo Record for local movie listings, and the Toronto Star for Doonesbury.

I didn’t realize it was the twentieth anniversary of Kent State until I saw a commemorative article in the first paper I read. That article was written by a Kent State journalism student who happened to be in the right place at the right time to get the greatest news story of his life. The reporter told about his day: the rumors that something bad had happened at the noon rally, his race to get his camera, his sneaking through bushes to reach the parking lot where the killings took place, many details about the aftermath... but strangely, the reporter omitted any information about the victims themselves. He didn’t even give their names.