Nemesis: The Death Star - Richard Muller

I imagine most people know about the meteorite that struck the Earth near the end of the Cretaceous and at bare minimum, helped speed the dinosaurs along into extinction (minus the birds, of course). What I didn't know is that there's a theory that several of the mass extinctions in Earth's history have been the result of such collisions, and that they're due to a small star that's in a binary system with the Sun, which brushes past the Oort Cloud every 26 million years or so and sends a bunch of comets hurtling into the solar system.

But apparently that's a thing, and Muller's book is a sort of history of how that theory came about. He starts with a pair of scientists who note that the fossil record suggests there are mass extinctions every 26 million years ago, and how one of his mentors, a Dr. Luis Alvarez, was intrigued by the notion. The book starts a bit slow, because Muller spends a lot of time talking about Dr. Alvarez, and then still more time talking about the development of the theory a meteor strike killed the dinosaurs. Which seems like old hat to us, but the events in the book take place in the 1970s and '80s, so it was a big new thing back then.

The book is probably most interesting for the look it offers into theoretical science. The need to question theories and evidence carefully, but not reject them outright because they don't match expectations. To not take it personally if someone points out flaws in your own theory, and to be willing to solicit outside help. Especially in things outside your field of expertise. Muller's an experimental physicist, as is Alvarez. Over the course of this book, they work with geologists, paleontologists, orbital dynamicists, astronomers, chemists, etc. Because contrary to Reed Richards, it's pretty damn hard to be an expert in every field of science.

The book also shows, like Song of the Dodo, that the scientific community can be extremely petty and childish. Not all of them - Muller highlights several scientists who publicly admit either they screwed up their calculations, or that they doubted the theory but did their own testing and were proven wrong - but there are several who stubbornly persist in a particular belief, despite not being able to provide any evidence to support it, or to refute the alternatives.

This book was written in the '80s, but the same place I found it, also had a more recent book written by one of the scientists who noted the periodicity of the extinctions revised in the late 1990s I'm going to read next. We'll see what they came up with in the interim.

'If there was a star orbiting the sun, we would have to change our entire theory of the origins of the solar system. The star would have been a decisive factor in the evolution of life, due to its periodic shotgunning of asteroids at the Earth. The asteroid that killed the dinosaurs had been the bullet, but the solar companion star was the murderer. The very revolutionary nature of the idea made me think that it was unlikely to be true.'