In his latest book, retired UC Davis physics/atmospheric science professor Tom Cahill imagines an asteroid slamming into the Earth. He has it strike far from Davis, but the distance doesn’t matter—Davis is wiped out (by a huge flood) anyway, as is most of the world in an ensuing ice age. This sets the stage for a tale about climate change, and how survivors adapt.Today we discuss “Ark: Asteroid Impact,” plus some of Cahill’s other interesting work studying the threat of airborne particles from the 9/11 annihilation of the World Trade Center—he’s a national expert on the subject—and from railroads and freeways. Turns out that Davis, bisected by Interstate 80 and a Union Pacific railroad mainline, is lucky to be located where the routes are largely straight and flat.