A Nobel laureate draws on present-day knowledge to animate this fine history of science.

Review by Clive Cookson

Steven Weinberg may not be a household name like Stephen Hawking but within the world of science he is regarded as the preeminent theoretical physicist alive today: a Nobel laureate and, more importantly, a key contributor to the so-called Standard Model, which is the most complete theory of fundamental forces and particles formulated to date. Weinberg is also a fine writer and communicator about ideas beyond his own field, as he shows in this history of science, particularly physics and astronomy, over the past 2,500 years.
Weinberg, 81, has clearly carried out extensive scholarly investigation for To Explain the World, as more than 25 dense pages of references and bibliography show, and the book works as history. But what makes it stand out is his perspective as a top scientist working today. Rather than taking the view, as some do, that histories of science should not be immersed in modern knowledge, Weinberg makes a point of illuminating ancient Greek, Islamic and medieval European science from a contemporary viewpoint.
He is not afraid to take down great figures, from Plato and Aristotle to Descartes. As he writes, “a historian who devotes years to study the works of some great man of the past may come to exaggerate what their hero has accomplished.” Weinberg’s aim is to show “how far these very intelligent individuals were from our present conception of science,...how difficult was the discovery of modern science, how far from obvious are its practices and standards.”
To Explain the World focuses mainly on two distinct periods: ancient Greece and the “scientific revolution” of 16thand 17th-century Europe. His story begins in the Ionian city of Miletus in the early 500s BC, when Thales began serious thinking about geometry and about the nature of matter, which he declared to be composed of a “single fundamental substance”. A vast number of Greek names feature in the first 100 pages, laying the foundations of what we now call physics, astronomy and mathematics (the book has much less to say about biology and medicine). In many cases, unfortunately, little of the original writings survives beyond fragments but Weinberg does a good job reconstructing at least the gist of their work. Although Greek science began in small independent city-states, its great flowering took place later in the Hellenistic era and, above all, in the Roman empire. As Weinberg notes (but does not explain), Greeks remained at the intellectual heart of the classical world for hundreds of years. He draws a stark contrast between the underlying attitudes of science then and now. “There is an important feature of modern science that is almost completely missing in all the thinkers I have mentioned, from Thales to Plato: none of them attempted to verify or even...seriously to justify their speculations,” he writes. “In reading their writings, one continually wants to ask ‘How do you know?’ .” Observations, for example of the stars and planets, are fed into theories but there is nothing like the modern idea of experimenting to test a theory. In the Greek part of the world, Weinberg argues, science reached heights not regained until the 16th century. The millennium between the fall of Rome and the scientific revolution that began with Nicolaus Copernicus was not a complete intellectual desert, he concedes — paying due respect to medieval Islamic science — but he has little time for Christian Europe before the Renaissance. The second part of the book covers ground that is more familiar — at least to this reader — than the first part. We move from Copernicus, through Tycho Brahe, Johannes Kepler, Galileo Galilei and Christiaan Huygens, to reach a climax with Weinberg’s hero Isaac Newton. And the solar system changes, from an Earth-centred model with the planets and sun rotating around us in circular patterns that require complicated corrections to match astronomers’ observations, to a Sun-centred model with Earth and the other planets in elliptical orbits. Of course science still has a long way to go. In a few centuries from now, our 21st-century theories about the universe, even the partial explanation offered by Weinberg’s Standard Model, may seem as absurdly contrived as the epicycles, eccentrics and equants of ancient Ptolemaic astronomy.

Clive Cookson is the FT’s science editor.