Lisa Randall and the Dinosaurs

By: John Farrell

While it’s not as engaging as her previous books, Lisa Randall’s new title, Dark Matter and the Dinosaurs provides a broad survey of current cosmology and makes a great holiday science gift idea, especially if you’re thinking of readers knew to the genre.

According to Randall, a theoretical particle physicist at Harvard, it was a post-lecture discussion she had at a conference with Paul Davies, author of some of my favorite cosmology books, that inspired her to look into what first sounds like a completely whimsical notion: was the asteroid impact that is believed to have wiped out the dinosaurs 66 million years ago caused by gravitational perturbations from a galactic disk of dark matter?

This is the kind of big question that could be answered in two ways: flippantly by you and your colleagues after a few drinks in the conference hotel bar–or … by months and months of checking in with a lot of scientists way outside your field of expertise (and your comfort zone). Randall opted for the latter and an exhilarating marathon 412-page survey of the state of the universe is the result.

How do scientists know there must be something called dark matter, a substance which makes up 85% of the matter of the known universe, but can’t be detected by any form of light? The short answer is gravity: dark matter’s only interaction with the other 15% of ‘normal’ matter (protons, neutrons, etc) is its gravitational influence on stars and galaxies.

There’s a complicated history behind this and Randall covers it in depth in parts one and three of her book: why cosmologists began to take the idea seriously, how they are searching for evidence of the elusive stuff, whether it is made up of its own collection of fundamental particles, etc. As a result, some readers may get lost long before she gets to the doomed dinosaurs of the late Cretaceous period and the possible connection between their messy fate and an elusive mass of matter that can’t be seen or touched.

The asteroid that ‘killed’ the dinosaurs has entered the popular consciousness in films and books. But there are some problems with the scenario. Randall shows that it was more likely a comet than an asteroid. But as one geologist told me, the impact scenario is falling out of fashion amongst specialists in the field. At the two most recent annual meetings of the Geological Society of America, he said, the focus had shifted to massive volcanic eruptions being the greater factor in the dinosaurs’ extinction. Randall touches on this briefly to be sure, but she might have devoted more space to the debates and controversies that engage geologists and paleontologists today.

One concern for regular science buffs is that the broadness of her topic forces Randall to write the whole book as a series of lectures. They’re superb lectures and she’s very careful to guide her readers along. But it’s a lot of ground to cover, and it comes at the expense, I think, of her personal voice, which was much more pronounced and engaging in her previous book, Knocking at Heaven’s Door.

My own wish is that the book had been written more like a journal: that she devoted more space to the delightful oddity of  being a particle physicist suddenly finding herself chasing down geologists and paleontologists.

But that aside, Dark Matter and the Dinosaurs is top notch in the cosmology genre this year, especially as a gift this holiday season.


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