Dark Matter and the Dinosaurs, by Lisa Randall

This week I'm talking about a book which I originally heard about on NPR and managed to find as an audiobook at my library. Unfortunately, and I really hate to say it, I don't think I fully understand this book. From what I was able to muddle through Dark Matter and the Dinosaurs is, ostensibly, about a hypothesis which Randall admits needs significantly more testing and research and could very likely be ruled out in the future. What we do know is that about 66 million years ago a large object, either an asteroid or a comet, hit the earth in what is now the Yucatan peninsula and directly caused the Cretaceous-Paleogene extinction, the fifth mass extinction found in the fossil record and the one which killed off the dinosaurs.

Why this object hit Earth at this particular time remains largely a mystery and so far our best working theory is just random chance. Comets and asteroids pass by Earth all the time and thousands of small meteoroids fall into the atmosphere in the course of a year, creating shooting stars. Simple laws of averages means given sufficient time, a comet or asteroid of a size big enough to cause the KPG extinction (Cretaceous-Paleogene, the C is already used for Cambrian) is bound to happen eventually. However, the fact that this appears to not be the first such event has made scientists curious as to whether or not there is some sort of underlying pattern to these impacts. Randall and one of her colleagues has submitted the hypothesis that perhaps a mass of dark matter is responsible for sending objects from the Oort Cloud on the edges of our solar system.

This is where it gets really confusing because dark matter is kind of hard to understand and I found myself really confused during a lot of this. Although I also didn't feel too bad because Randall states dark matter is in and of itself somewhat hard to understand. Basically dark matter, as scientists understand it, makes up about 85% of the mass in the universe. The name comes from the fact dark matter doesn't interact with light at all, making it invisible to us. In fact, it doesn't seem to interact with matter on most levels which makes it frustratingly difficult to study. So how do we know that it exists at all? Well much like how you can't see the wind, you can detect its presence by measuring its effects and dark matter does exert gravitational pull. Astronomers first hypothesized dark matter existed because they realized our galaxy, and presumably other galaxies in general, simply didn't have enough mass to make everything work properly. So they suggested there was another form of matter we simply weren't aware of that was providing the additional gravitational pull. Astronomers have since discovered light from distant stars being bent in various ways, as if by a large mass, which may suggest the evidence of dark matter. Although it's still very difficult to understand and physicists are still making numerous attempts to better understand and hopefully find dark matter.

So, that's pretty much all I understood about dark matter from the book, and even then I'm not entirely sure I got that right. Obviously it's best if you look at the book yourself for a more complete explanation. Which is what gives me great pause in talking about this book. But on the other hand there's a lot of issues from an organization standpoint in this book as well.

The feeling I got with this book was ''shotgun''. Randall makes a lot of points and they seem scattered all over the place with no specific theme or connection. At least until the very end but it feels tenuous at best. Randall covers subjects such as dark matter, the Big Bang, the development and composition of the solar system, the evolution of life on earth, mass extinction events, and the study of craters. It feels very eclectic and while it's all eventually tied to the hypothesis of dark matter influencing the orbit of a comet which hit earth and caused the KPG extinction, it becomes very easy to loose the thread while you're reading, or in my case listening, to the book.

And honestly, other than the dark matter bits which I cannot emphasize enough I do not fully understand, a lot of it felt like review to me. It was kind of cool to learn that our understandings of the KPG extinction were in fact fairly recent, as well as our increasing understanding of the solar system, but having been exposed to quite a lot of science in school myself quite a lot of it felt rather familiar to me. Plus it dealt with ordinary things made of matter which I can more easily relate to. So the book went between the extremes of mostly review and being well out of my depth for me. I'm not sure what the experience would be like for other readers because I feel it may depend on your scientific literacy.

I guess I understand the why, because it ensures Randall's readers fully understand all the concepts before she puts forth her hypothesis. But I feel like it could have benefitted from some better organization to make it more cohesive.

Overall I just don't think I can pass judgement on this book because I just don't understand a lot of the parts about dark matter. Maybe if I had been able to look at the included diagrams it may have helped my understanding, but so far I'm very much out of my depth of understanding.

- Kalpar