David Bodanis begins his 2016 book Einstein's Greatest Mistake with a depiction of a once-great scientist who had become a forlorn figure in his later years. He was usually alone when he walked home after a day at the Institute for Advanced Study in Princeton, New Jersey, isolated intellectually and socially from other scientists, many of whom "no longer took his ideas seriously" (p. xii). How Einstein got to that place in his life is for Bodanis to explain. The author's account is plausible, in my view, and reveals interesting facets of Einstein's personality along the way.
There actually are two major scientific mistakes Einstein made in his scientific career, his response to the first likely affecting his response to the second. Among Einstein's many accomplishments -- including the five momentous discoveries of his annus mirabilis (miracle year) of 1905 -- his 1915 general-relativity conception of gravity arguably is his best-known scientific contribution (along with E = mc-squared). The offshoots of general relativity, according to Bodanis, include "explaining why black holes exist, showing how the universe began and how it will likely end, and even laying the foundation for revolutionary technologies such as GPS navigation" (p. xii-xiii).
But there seemed to be a problem with general relativity. Conventional wisdom among astronomers at the time was that the size of the universe was constant. Yet, Einstein's general-relativity equations allowed the possibility of the universe expanding or collapsing (see pp. 115-116). To align with notions of a static universe, therefore, Einstein introduced a new term -- known as the cosmological constant or lambda -- into his formulation.
Unfortunately for Einstein, that was not the end of the story. As the book describes, in 1929 Edwin Hubble and his associate Milton Humason determined from observations of the movement of stars and galaxies that the universe was indeed expanding. Einstein's equations were right the first time and now lambda could be eliminated (see pp. 135-154). A valuable aspect of this part of the book is its reporting on the work of less well-known scientists whose work informed the debate, such as Father Georges Lemaitre (click here for my review of The Day Without Yesterday, about Lemaitre's work), Alexander Friedmann, and Henrietta Leavitt.
The general-relativity/universe-expansion debacle only seemed to harden Einstein's resolve to stick to his own theories no matter what. As Bodanis noted, "When [Einstein's] critics tried to bring in evidence against his later beliefs, he ignored them, confident that he would be vindicated again" (p. xiii). From this stance emanated Einstein's second major mistake.
As Bodanis describes, from the early 1910s through the early 1930s, the study of quantum mechanics (QM) at the microscopic level of matter developed alongside the study of relativity at the large level of stars and galaxies. QM had a number of odd features, such as probabilistic predictions that a particle might end up in one place 70% of the time and in another place 30%. Einstein objected vigorously to this proposition, leading to his famous statement about God not playing dice with the universe.
At first, Einstein engaged with the ideas of quantum mechanics -- in an attempt to discredit them. Particularly interesting, as the book recounts, were the Brussels conferences of 1927 and 1930. Each morning, as the elite coterie of physicists (including QM proponent Niels Bohr) gathered for breakfast, Einstein would issue a daily challenge to QM, proffering some kind of thought-experiment that seemed to undercut the logic of the theory. Bohr and like-minded colleagues would then spend large amounts of time, sometimes deep into the early-morning hours, trying to rebut Einstein. Ultimately, the pro-QM group successfully answered Einstein every time.
According to Bodanis, "Einstein never again attended such a meeting; never again attempted to refute Bohr or [Werner] Heisenberg in public debate. Nor, however, did he change his beliefs." (p. 204).
The rest of Einstein's career, until his death in 1955, was largely an intellectual waste, according to Bodanis. These years were filled with missed opportunities. Potential collaborations with other leading physicists either fell through or did not interest Einstein in the first place. Princeton faculty “worshipped Einstein and would have relished the chance to collaborate with him. Their studies ultimately helped lead to the creation of the transistors that today operate inside all our phones and electronic devices. But Einstein couldn’t bring himself to grapple with these strange consequences of the new quantum mechanics“ (p. 219)
Even when Bohr visited Princeton in 1939, gone were Einstein's spirited and detailed challenges to Bohr. As the book notes, Einstein avoided most opportunities to interact with Bohr and when the two were together, "Einstein would speak only in banalities" (p. 226).
For laypersons interested in a non-technical exposition of Einstein's and his intellectual opponents' ideas -- along with the human drama of Einstein's career arc -- it would be a great mistake not to read this book!