Excerpt from The MANIAC by Benjamin Labatut, plus links to reviews, author biography & more

As a physicist, he made no earth-shattering discoveries, but he enjoyed the full respect of such towering figures as Niels Bohr, Paul Dirac, and Wolfgang Pauli. Albert Einstein wrote that, no more than a few hours after having met Paul, he felt "as though our dreams and aspirations were meant for each other." These friends of Paul's admired not only his critical and intellectual capacities but something rather different, a virtue that is usually lacking among giants: ethics, character, as well as a deep, some would say overwhelming, desire to understand, to grasp the core of things. Ehrenfest sought relentlessly what he called der springende Punkt, the leaping point, the heart of the matter, as for him deriving a result by logical means was never enough: "That is like dancing on one leg," he would say, "when the essence lies in recognizing connections, meanings and associations in every direction." For Ehrenfest, true understanding was a full-body experience, something that involved your entire being, not just your mind or reason. He was an atheist, a doubter and a skeptic with such a rigid standard for truth that he sometimes became a figure of fun among his peers: in 1932, at the end of a meeting of three dozen of Europe's best physicists at the Niels Bohr Institute in Copenhagen, a parody of Faust was staged to celebrate the centennial of Goethe, and Paul was cast as the great scholar Heinrich Faust himself, unwilling to be convinced by the demon Mephistopheles, portrayed by Wolfgang Pauli, of the existence of the neutrino, a newly postulated fundamental particle.

They called him the Conscience of Physics, and while there was a hidden barb in that nickname due to Ehrenfest's undeterred opposition to the road that not only physics but the whole of the exact sciences seemed to be taking during the first decades of the twentieth century, many of his colleagues would visit him regularly at his home in Leiden, just across the river from the university, to try their ideas on him, and on his wife, since Tatyana Alexeyevna Afanassjewa was an accomplished mathematician in her own right. She coauthored some of Ehrenfest's most important scientific papers, including the one that first made his name (though it did almost nothing for her career) and eventually led to his appointment as successor to the much-revered Lorentz: it was a summary article on statistical mechanics, a favored subject of his mentor, the ill-fated Ludwig Boltzmann. Boltzmann was one of the strongest advocates of the atomic hypothesis, a veritable trailblazer who first discovered the role that probability plays in the behavior and properties of atoms. Like Ehrenfest, Boltzmann also suffered greatly during his restless and unhappy life, crippled as he was by severe bouts of uncontrollable mania and abysmal depression, the effects of which were compounded by the vicious antagonism that his revolutionary ideas bred among his peers. Ernst Mach, a staunch positivist who contended that physicists should not speak of atoms as anything but theoretical constructs-since, at the time, there was no direct evidence for their existence-hounded and mocked Boltzmann without end, interrupting one of his lectures on atoms with the mean-spirited question: "Have you ever seen one?" The Bull, as his friends called Boltzmann due to his corpulence and his stubborn tenacity, despaired at the ferocity of his critics, and even though he laid down one of the fundamental equations of modern physics, his statistical interpretation of the second law of thermodynamics, in his personal life he could not escape the slow and constant advance of his mental disorder, which seemed, like the entropy of the universe he had so wonderfully captured in his equation, to be constantly and irreversibly increasing, leading to inevitable randomness and decay. He admitted to his colleagues that he lived in perpetual fear that he might suddenly lose his mind during a lecture. Toward the end of his life he could hardly breathe from his asthma, his eyesight dimmed to the point where he could no longer read, and his headaches and migraines became so utterly unbearable that his physician ordered him to completely abstain from any scientific activity. In September 1906, Boltzmann hanged himself with a short rope from the crossbars of the window frame in a room at the Hotel Ples, during a summer holiday in Duino, near Trieste, while his wife and young daughter were out swimming in the calm, turquoise waters of the Adriatic.

Excerpted from The MANIAC by Benjamin Labatut . Copyright © 2023 by Benjamin Labatut . All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.