As Far as We Know – Paul Callaghan & Kim Hill ****
We don’t often associate science with conversations. Science interviews are usually short media exercises, and science seems too serious and rigorous to be approached by unstructured dialogue. “As Far as We Know”, a series of radio discussions about science between a distinguished broadcaster (Kim Hill) and equally distinguished scientist (Paul Callaghan), is not a work of science. But it does have a serious aim: to answer the question “What is science?” It may not answer the question to everyone’s satisfaction. But it does show the power of conversation to illuminate – and lighten up – science.
So what is science, according to this book? It is, says Callaghan, a “means of looking at the world to try to understand natural phenomena and their causes in a way that is self-consistent and corresponds to reality.” Callaghan sees a sharp line between what is science and what is not, and doesn’t miss many opportunities to draw it. In this book, creationism, homeopathy, and phone cancer all get a dose of Popperian medicine. Some of Callaghan’s prescriptions have a dogmatic odour. “Doubt is at the very heart of science,” he says. Granted, scientists are trained to doubt. But surely they are also trained to find the most rigorous demonstrations possible for any given claim? “[Scientists] never hold on to some cherished belief in the face of evidence to the contrary.” As Callaghan must know, scientists do this often – and often with good reason. But to his credit, Callaghan readily admits that science means not having all the answers – not yet, anyway – and that scientists are no better than non-scientists when it comes to sorting through the ethical implications of science.
So far, so many platitudes. But the stand-out feature of this book is not what Callaghan and Kim Hill say about science but what they do with it, their patient question-and-answer probing at some basic puzzles of science. After decades of live interviews, Hill can be puzzled and probing with equal success, sometimes pulling Callaghan back to the level of the lay listener (“Hang on, you’re losing me”; “Is heat a synonym for energy?”) and sometimes pushing him into a more exact or convincing account of one or other area of science (“Have you already answered my question then?”; “For example?”; “How do you know that?”; “Is that a metaphor?”; “Is that what he [Newton] intended to do?”). She has clearly done her homework: she knows about Dirac’s coincidence, the medieval warming period, and the difference between chaos and complexity; and she has read Simon Singh, Matt Ridley, and Martin Rees, and is not afraid to quote them.
For his part, Callaghan “wears his learning lightly,” as Martin Rees puts it in his glowing preface. He covers Archimedes, William Gilbert, Karl Popper, J.J. Thompson, and the impact of refrigeration on New Zealand real estate, as easily as he covers thermodynamics, sexual selection, and the physics of colour. His explications a clear and crisp, and he laces the science with stories, histories, and popular references – like his experience with colour therapy, a Dire Straights CD, and the story of the man who ate polonium-210. He likes the poetry of science, its “beautiful words” and “lovely thoughts.” One can imagine Professor Callaghan lecturing to a large audience. But one can also imagine calling him “Paul” (as Hill does) and inviting him round for dinner (as Hill would like to, judging by her happy banter in these conversations).
The conversation is worthy of the conversationalists. The topics are the ingenious designs of nature and the ingenious attempts by scientists to find and exploit them, and both speakers have a real fascination for their subject matter. Why are there two human genders and why is there a 50/50 split between them? Why are there two human genders at all? Why is the ratio of smallest things to the largest things the same as the ratio of the smallest forces to the largest forces? Why is a digital signal more reliable than an analogue signal? Why is the shape of a protein so important and how does it take on that shape? What evidence do we have for the Big Bang, evolution, and the existence of atoms? These questions are primarily chosen not for their sex appeal, God appeal, or news value, but for their scientific interest. Questions like these, and speakers like Hill and Callaghan, make for a fine popular conversation about science: spontaneous, topical, relaxed, witty, and penetrating.