By Jermey N. A. Matthews
Harvard University theoretical physicist Lisa Randall addresses questions about the properties and interaction of matter in the standard model and beyond. She has developed and studied a wide variety of models including the Randall–Sundrum model, which involves extra dimensions of space. She is a member of the National Academy of Sciences and author of the science popularization Warped Passages: Unraveling the Mysteries of the Universe’s Hidden Dimensions (Ecco, 2005), (reviewed in Physics Today, December 2005, page 59). Her latest popularization is Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World (HarperCollins, 2011). Physics Today recently caught up with her to discuss that book.
PT : What motivated you to write this book?
Randall : I had two separate aims in this book—explaining the goals and ideas in particle physics today and explaining the true nature of science. Having already written Warped Passages, in which I discussed many contemporary ideas in particle physics, I wasn’t keen to write something overly similar. But during the few years after it came out, I became increasingly disturbed by the misunderstandings people have about science. Stories in the news show that a significant fraction of the public doesn’t understand how science works, at a time when it is more important than ever for scientists to get their ideas across. I wanted to believe, perhaps optimistically, that once people had a better understanding of both of science itself and the scientific method they would make better decisions.
In particular, people have an idea about science as a clean set of infinitely precise ideas. But research by its very nature is messy, and only over time do ideas get tested and validated. A big part of the art of science is sorting through uncertainties to make statements that are correct in precisely stated parameter regimes with a certain degree of accuracy. In this book I emphasize the importance of scale in understanding how theories relate to and build on each other; the nature of uncertainty; the interaction between theory and experiment; and the role of creativity, model building, aesthetic criteria—I’m more contrarian than you might think—and observations in shaping theoretical ideas.
Of course, it’s also a very interesting time in particle physics, with the Large Hadron Collider [LHC; at CERN] running and many dark-matter searches in progress. I wanted to describe those in some detail and explain the questions we are trying to answer. I don’t cheat when I describe the ideas, so I hope to give a more complete picture that allows the reader to understand the questions we ask and how we go about answering them. I hoped that people would learn enough that they can be more deeply involved as the LHC and other experiments reveal their results. People who are curious about particle physics and cosmology should have the opportunity to know more.
PT : How did you decide on the title?
Randall : I wanted to express the idea of how science builds on itself. We have a solid core of knowledge with a well-studied range of applicability. But we are constantly probing the edges—trying to go beyond what is known to get a deeper understanding.
And I was being playful. It was intriguing to use a title from popular culture—even if I intend a completely different meaning. Those who read Warped Passages saw this in the song quote for each chapter, referring whimsically to the ideas the chapter contained. Using a song title for my book was a small shout-out to this idea.
PT : What did you learn from Warped Passages that shaped the way you wrote this book?
Randall : Mostly I learned how to be patient with the reader and build up ideas sequentially and logically so they can follow through. It was interesting for me to view the puzzles in writing in ways similar to puzzles in science—how to get from here to there without any inconsistencies or too many extraneous diversions en route.
But I also learned how differently people learn and see science, and how differently people read in general. There is no single way that everyone learns. Some people immediately see connections that others do not, and some prefer an analogy while others prefer a picture. And some will immediately absorb scientific knowledge into their worldview, while others will take a while to develop the connection to their way of thinking.
I therefore chose to aim some material at readers who already had a strong interest in the type of science I do, but to also do new things in this book by explaining some core scientific concepts to keep it more interesting for both me and, hopefully, the audience.
PT : What is your synopsis of the current results from the LHC?
Randall : At the moment we mostly have limits. Supersymmetry is more constrained; the extra-dimensional models I work on can’t have very low energy consequences; and the simple fundamental Higgs boson is excluded except with mass in a very narrow range. That’s a very successful story for a machine that has only run at half its intended energy and at only a fraction of its ultimate luminosity. But of course it’s not yet what we’re hoping for.
Next year we’ll probably know whether or not current hints of a light fundamental Higgs boson are correct and know even more about what’s possible for beyond the standard model theories. But very likely we will have to wait for higher energies to make other discoveries, which is actually not too surprising based on lots of indirect evidence we already had.
PT : What books are you reading at the moment?
Randall : I just finished Peter Carey’s Jack Maggs: A Novel (Alfred A. Knopf, 1998). The last book I finished before that was A. M. Homes’s latest novel—out next year—which she asked me to comment on during the final editing stage. It was full of funny and astute observations, so I was glad to do so. One of the perks of writing has been meeting interesting writers and having the opportunity to share ideas with them.
