Steven Weinberg became famous for his elegant The First Three Minutes (1977), which described what happened during the Big Bang. Two years later, he shared a Nobel Prize for unifying electromagnetism and the nuclear weak force – a large step towards today’s Standard Model of particle physics. The citation for his Benjamin Franklin Medal of 2004 said he was widely considered “the preeminent theoretical physicist alive today”. To Explain the World, his twelfth book, tells of the long, hard struggle to arrive at modern science, which started to take something like its present form only in the sixteenth and seventeenth centuries. The book is a magnificent contribution to the history and philosophy of science.This review might not stay freely available.
It tells an exciting story. Why on earth did good science take so long to arrive? Weinberg’s answer, the book’s main theme, is that it was so immensely difficult to learn what there was to explain, and how to set about explaining it. Explanation by bringing a wide range of facts under a single theory; the need, often, to state theories mathematically; which principles (looking for simplicity, for instance) were sometimes helpful in arriving at theories – all such things had to be painfully learned. Other principles (such as seeking purpose and the good) called for painful unlearning. At first, even the need to submit theories to observational tests was not grasped by the world’s best brains. For, Weinberg comments, people “had never seen it done”.
The tale begins with Ancient Greece. The Pythagoreans, inspired perhaps by comparing the lengths of harmoniously tuned strings, concluded that mathematics dictated all the laws of the cosmos. In reality, Weinberg points out, mathematics by itself “cannot tell us anything about the world”; we need actual observations as well. Without observational support, Plato declared that the world’s four elements, water, air, earth and fire, were composed of regular polyhedrons. Fire was the tetrahedrons, earth the cubes. Weinberg thinks we should best understand such declarations as “poetry”, not as trying “to say clearly what one actually believes to be true”. “Intellectual snobbery” among the early Greeks often made them dismiss as “not worth having” any grubbily acquired knowledge of the material world. Weinberg gives Democritus no praise for proposing atoms. The man seems to have made no effort to show “that matter really is composed of atoms”.
He seems to emphasize astronomy as being crucial for the development of mathematical science. This seems right to me.