The Day Without Yesterday (Polygon) is Stuart Clark’s just-released final novel of a historical trilogy of novels exploring the development of modern astronomy from Galileo, Kepler and Newton to Einstein. In this final book of the series, Clark examines the emergence of the Big Bang theory, taking in quantum physics along the way. I’ve read and reviewed the two earlier books in this trilogy and have been very impressed by the way Clark weaves together the stories of different historical characters into a coherent whole, not only getting across the revolutionary nature of their discoveries but also presenting them in the historical context to show how their contemporaries (mis)understood their findings.

This latest book doesn’t disappoint. This is the story of how the revolutionary theories of general relativity and quantum theory came to be generally accepted, and how they triggered the development of the Big Bang theory. Clark tells the stories of Einstein, the American astronomer Hubble and lastly, and perhaps most interestingly, the Belgian Lemaître.

The first two books in this trilogy made clear how astronomy’s growth as a modern science was threatened by the religious authorities who saw a threat to their power from its growing ability to explain and predict natural phenomena. There is a nice counterbalance to this antagonism between religion and science in The Day Without Yesterday in the story of Lemaître, a great theoretical physicist who was also a devout Roman Catholic priest, and who saw no conflict between those two aspects of his life.

The main character in the book is Einstein, and the story starts with his efforts to define the theory of general relativity. Because this was published during the First World War, it was little known outside Germany until the English physicist Arthur Eddington realised its prediction of starlight being curved by the Sun could be tested experimentally. He famously carried out this experiment during the solar eclipse of 1919, cementing Einstein’s reputation (and his own). In fact, as this novel makes clear, German astronomers had been trying to make this measurement before 1919, and near the beginning of the book is an account of their tragi-comic efforts to do so, during a trip to the Crimea in 1915. As Germany was at war with Russia, the German astronomers were arrested and charged with spying. A telescope is not only useful for observing the stars…

Students of physics and astronomy know Lemaître from the two equations that describe the expanding Universe. but he was not the first person to have derived those equations. Perhaps for reasons of clarity or brevity, the book doesn’t go into the story of Friedmann, the Russian physicist who derived the equations in 1922, five years before Lemaître.

But Lemaître’s story is fascinating: he fought to defend Belgium against the Germans in the First World War before becoming a priest. He showed that Einstein’s description of the Universe as essentially static and unchanging was not the only solution to general relativity’s field equations. Einstein had famously added in lambda, a fudge factor, to his equations to ensure that the Universe stayed balanced on a knife-edge between expansion and collapse, because he initially couldn’t accept that the Universe wasn’t fixed for eternity. The irony is that since Lemaître and others developed these equations, evidence has been found for a greater-than-expected expansion of the Universe and now lambda has been put back in the equations to represent this expansion (possibly due to dark energy).

Einstein doesn’t come out very well in this book, either professionally or personally. It is all too clear that general relativity was his last great achievement, even though he lived for another forty years. Indeed, although he had been one of the pioneers of quantum physics, he stopped believing that it was anything but an approximation to a better theory which would do away with its inherent uncertainties. The book is perhaps slightly too harsh on his criticisms of quantum physics; in fact his long-running arguments with Bohr and the ingenious thought experiments he devised genuinely advanced the subject, however wrong-headed his views. But there is no dodging the fact that he neglected his first wife and their children, and the book describes an extraordinary episode when he thinks he has fallen in love with his soon-to-be step-daughter.

Twentieth century astronomy is so rich in extraordinary characters that I was left wishing the book was twice its length so it could have space to tell us more about the eccentric American astronomer Hubble who affected an upper class English accent, or Cecilia Payne-Gaposhkin, the first woman to get a PhD in astronomy from Harvard, or the ‘computers’ at Harvard: women such as Henrietta Swan Leavitt who discovered the relationship between periodicity and luminosity for some variable stars, thus allowing accurate distances to galaxies to be measured – something Hubble relied on in his work.

Of course, this is an unfinished story; we haven’t yet figured out how to combine general relativity with quantum physics, and what triggered the Big Bang. I still hope that Stuart Clark will one day write a follow-up to this trilogy and bring us more up to date.