For each of the 12 days of Christmas, here鈥檚 something to beguile, distract 鈥� and leave you with questions to take into 2016
HOW do you know if you鈥檙e onto something in science? According to University of Manchester physicist Andre Geim, it starts with a feeling: a nagging pull in your gut tells you that your crazy idea is worth exploring. So, with bated breath, you give it a try. The result is usually failure 鈥� whether or not the idea has merit. 鈥淭hen, you may or may not try again,鈥� says Geim in his autobiography.
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Throughout his career, Geim has tried again with many different projects. Just occasionally, he says, 鈥渇ailures sometimes failed to materialise鈥�. And if you are far enough out from the mainstream when your project fails to fail, it鈥檚 far more likely that your surprise success will have some significance 鈥� hence Geim鈥檚 Nobel for the discovery of graphene.
Lisa Randall is certainly far from the mainstream in .
She has an as-yet unproven idea about the nature of the as-yet undetected dark matter that may (or may not) make up 80 per cent of the universe鈥檚 mass. Then physicist Paul Davies at the University of Arizona suggested this idea might account for the demise of the dinosaurs. Should that have been the point where she walked away?
鈥淢eteoroid hits are challenging enough to investigate,鈥� Randall says. 鈥淐oupling them with uncertainties about extinction events is bound to go down a convoluted rabbit hole of trouble.鈥� But she went down the rabbit hole anyway. And, thanks to this fascinating account of the story so far, we can too.
It takes a particular kind of nerve to expose your research before it is shown to be right. That鈥檚 doubly true when the ideas seem ridiculously implausible at first glance. Perhaps Dark Matter and the Dinosaurs is a sign that readers of popular science have finally grown up and no longer need pureed 鈥渢riumph鈥� narratives of science.
After all, it is easy to digest happy-ending stories of derided speculations that turned out to be right all along. The uncompleted stories are more demanding. However, as Randall ably demonstrates here, they are ultimately more satisfying: there is something to chew on. Biologist Peter Medawar once ticked off scientists for giving the impression that research is always neat by adopting what he called 鈥渢he postures we choose to be seen in when the curtain goes up鈥�. Randall has invited us to the process, not the performance. We can see the script, the dress rehearsals, the rewrites, the fluffed lines. And this idea may not even make it to opening night.
Randall鈥檚 proposal is that our galaxy contains a disc of dark matter with unusual properties. Instead of interacting solely through gravity, as dark matter is thought to, the dark matter in the disc has its own set of interactions. Occasionally, the disc exerts a pull on some of the rocky inhabitants of the Oort cloud beyond the solar system鈥檚 planets 鈥� perhaps enough to dislodge a rock and send it hurtling towards a cataclysmic collision with Earth.
Clearly the idea is not without merit, because it has now been published in what might be the most prestigious journal in physics, (although without mention of dinosaurs). The idea that dark matter did for the dinosaurs is 鈥渟peculative鈥�, Randall admits, but in a good way.
After all, if every idea in science were sensible, we would be without quantum physics and relativity. Randall even questions the value of sticking with Occam鈥檚 razor, the principle that the simplest explanation is usually the best. 鈥淎lthough scientists tend to prefer simple ideas, they are rarely the whole story,鈥� she says.
鈥淩andall has invited us to the process鈥� We see the script, dress rehearsals, rewrites, fluffed lines鈥�
That said, to her credit she doesn鈥檛 fall into the trope of painting herself as a maverick fighting the mainstream. Nowhere in these pages does she give the impression she thinks she and her colleagues are right 鈥� except in pursuing something that is both intriguing and (so far) plausible. As a world-renowned theoretical physicist and her own harshest critic, she has the self-confidence to lay out the ideas without being overly defensive of the argument.
She happily pokes fun at herself, in fact. The stars aligned for this project, she says, and just before it began, a fortune cookie asked her: 鈥淲hat is the speed of dark?鈥� As she says: 鈥淚 didn鈥檛 know then that the words were indeed a sort of fortune, in that they more or less prophesied the research project I was about to commence.鈥�
The day she asked her collaborator Matthew Reece if he wanted in on the project was the day the Chelyabinsk meteor entered Earth鈥檚 atmosphere 鈥� and that was three days after Davies鈥檚 question about dark matter and the dinosaurs. And then there鈥檚 the simple joy of the idea: 鈥渄ark matter (yay!), meteoroids (yay!), dinosaurs (yay!). The five-year-old in all of us was intrigued,鈥� she says.
鈥淚f every idea in science were sensible, we would be without quantum physics and relativity鈥�
In the end, it has turned out to be a very grown-up quest. To answer the central question, we must learn the science of the entire universe: its origins in the big bang, the structure and origins of the solar system, the geology of our planet, the nature of biological evolution, the perils of extinction 鈥� and, of course, the biggest mystery in cosmology 鈥� dark matter. As Randall puts it, 鈥渢he physics of elementary particles, the physics of the cosmos, and the biology of life itself all connect 鈥� not in some New-Age sense, but in remarkable ways that are well worth understanding鈥�.
Randall鈥檚 writing is as laid back and unfussy as ever. If you appreciated her clear, straightforward style in Warped Passages and Knocking on Heaven鈥檚 Door, you won鈥檛 be disappointed by Dark Matter and the Dinosaurs.
In fact, she seems to have pared down the flourishes to a minimum. We occasionally see glimpses of her life 鈥� her 鈥渧ery messy office鈥� or an intriguing conversation with a taxi driver 鈥� but for the most part this is a straightforward primer: an introduction to each of the arguments that makes up her thesis, all tied together with an honest look at the plausibility of the whole. Maybe there鈥檒l be no deep impact in the end, but it鈥檚 certainly worth the journey.
Image credits: Top: Jeff Blackler/REX/Shutterstock; artist: Robert Indiana; Second image: James Thew/Alamy Stock Photo
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