Theories That Outlive Their Reasons

Nobody believes in the machine that produced modern physics. To arrive at the equations that govern light, radio, radar, magnetic resonance imaging, and every wireless device now in your pocket, James Clerk Maxwell pictured empty space as a dense lattice of spinning cells, kept turning in the same direction by rows of minute idle wheels wedged between them. The contraption was absurd, and he said so first. It has been gone for a century and a half. The equations it delivered have never once needed correcting.That mismatch is the subject of this book. Something in a scientific theory does the actual work of holding it up, and something else is only the ladder used to reach the roof - and the two are almost impossible to tell apart while the building is going up. Maxwell offers the cleanest case in the history of science, because he left a record of knowing the difference as he worked.Following him from a schoolboy's pins and string to the first color photograph, from the rings of Saturn to the demon who lost his argument two generations after his death, this book traces how one Scottish physicist noticed that a number measured in a laboratory was also the speed of light, and how the field concept he built on that coincidence became the standard shape of every physical law that followed. It also asks a harder question. Physicists have spent fifty years trying to fold the four fundamental interactions into a single expression, and the effort has produced one genuine triumph and one very long silence. The final chapters argue that unity is a property of our descriptions rather than a discovered fact about the world, and that the four interactions deserve to be judged by what they actually do.Written without a single equation, for readers who would rather understand a way of thinking than memorize a result.Keywords: physics, electromagnetism, history of science, philosophy of science, scientific discovery, unification, Victorian science

Nobody believes in the machine that produced modern physics. To arrive at the equations that govern light, radio, radar, magnetic resonance imaging, and every wireless device now in your pocket, James Clerk Maxwell pictured empty space as a dense lattice of spinning cells, kept turning in the same direction by rows of minute idle wheels wedged between them. The contraption was absurd, and he said so first. It has been gone for a century and a half. The equations it delivered have never once needed correcting.That mismatch is the subject of this book. Something in a scientific theory does the actual work of holding it up, and something else is only the ladder used to reach the roof - and the two are almost impossible to tell apart while the building is going up. Maxwell offers the cleanest case in the history of science, because he left a record of knowing the difference as he worked.Following him from a schoolboy's pins and string to the first color photograph, from the rings of Saturn to the demon who lost his argument two generations after his death, this book traces how one Scottish physicist noticed that a number measured in a laboratory was also the speed of light, and how the field concept he built on that coincidence became the standard shape of every physical law that followed. It also asks a harder question. Physicists have spent fifty years trying to fold the four fundamental interactions into a single expression, and the effort has produced one genuine triumph and one very long silence. The final chapters argue that unity is a property of our descriptions rather than a discovered fact about the world, and that the four interactions deserve to be judged by what they actually do.Written without a single equation, for readers who would rather understand a way of thinking than memorize a result.Keywords: physics, electromagnetism, history of science, philosophy of science, scientific discovery, unification, Victorian science