In September of 1906, the eminent physicist Ludwig Boltzmann was enjoying a brief holiday with his wife and youngest daughter, at the Hotel Ples in the Italian village of Duino near Trieste. Although he was scheduled to return to Vienna on the following day to begin a new series of lectures on theoretical physics, the deep depression that Boltzmann was experiencing did little to
set his mind at ease. Prone to episodes of despondency and in chronic poor health, Professor Boltzmann regarded his lectures with increasing dread. While his family and colleagues worried about the great scientist's declining mental state, nobody could have predicted what would happen next: as his wife and daughter were enjoying the Adriatic weather with a swim in the ocean, Boltzmann took a short cord from the crossbars of a window casement and hanged himself in his hotel room. It was his daughter, Elsa, who found the body.
Though shocked by Boltzmann's suicide, not all of his colleagues were completely surprised. Not only did he have a long history of emotional problems but he had made at least one previous suicide attempt. As early as May of that same year, the Dean of the Philosophical Faculty of the Imperial-Royal University where Boltzmann was a faculty member notified the Ministry that Boltzmann was suffering from a "serious form of neurasthenia" which made him unable to engage in any scientific activity. Boltzmann had been concerned enough about his own mental health that he admitted himself in a mental asylum near Munich in late 1905 although he quickly reconsidered and returned to Vienna.
Among his various students and colleagues, it was an open secret that Ludwig Boltzmann's academic career was quickly drawing to a close. Ernst Mach, among others, commented that Boltzmann had to be kept under constant medical surveillance since the possibility of suicide was ever present. The Boltzmanns had actually gone to Duino at Henriette Boltzmann's insistence: she was worried about her increasingly agitated husband and wanted a pleasant holiday to distract him. If she had any qualms about leaving him alone while she went out with her daughter, she showed no sign of it.
So who was Ludwig Boltzmann? And what eventually led to his suicide? Despite numerous tragedies in his early childhood (including his father's death from tuberculosis when Ludwig was only fifteen), he was a gifted student who enrolled at the University of Vienna at the age of nineteen and earned his doctorate three years later. Becoming an Assistant Professor a year after graduating, Boltzmann quickly distinguished himself with a series of papers on thermal equilibrium of gas molecules from which the celebrated Boltzmann equation was derived. He was also one of the first advocates of the atomic theory of matter despite stiff opposition from Ernst Mach and other prominent Viennese scientists.
Boltzmann's equilibrium work, as well as his proof of the irreversibility of macroscopic phenomena established him as one of the great physicists of the 19th century. Not only was he revered as a theoretical physicist, his research into the relationship between dielectric permittivity and refraction established him as a brilliant experimental physicist as well. Along with his work at Vienna, he took numerous sabbaticals which enabled him to travel to Heidelberg and Berlin to work with other eminent scientists such as Robert Wilhelm von Bunsen, Gustav Kirchhoff, and Herman Ludwig von Helmholtz. The range of Boltzmann's research and theoretical speculations led to his being offered a position as a professor of mathematics at the University of Vienna, largely on the strength of his physics work which showed the mark of a "decided mathematical talent".
It was during the course of his academic wanderings between different faculties that he met Henriette von Aigentler. Impressed with her intellect as well as her beauty, Ludwig proposed marriage to her (in writing) and she accepted (in writing). When her application to audit classes in physics and mathematics was rejected (women were barred from higher education at the time), Ludwig urged her to appeal and she eventually received an exemption to the men-only rule.
The charming letters that Ludwig and Henriette exchanged during their courtship years have been published in an independent volume (edited by one of their grandchildren) that reflects that deep intimacy of their married lives. The newly-married Boltzmanns spent fourteen years in Graz where Boltzmann managed to secure a position. His time at Graz was the most productive period of his professional life and he eventually earned a long list of academic honours both at Graz and at various foreign universities where he lectured on occasion. He and Henriette also had five children, two sons and three daughters of whom only the youngest, Elsa, was not born in Graz.
So when did his psychiatric problems begin? His years at Graz seemed idyllic enough aside from growing problems with myopia which made reading increasingly difficult for him. It was in January 1888 that he first began showing signs of deep restlessness that caused him to become increasingly dissatisfied at Graz. Along with the politics that came with his new position as University Rector, Boltzmann was offered the opportunity to move to Berlin and assume a new position there. Accepting a post in another country without asking for permission from the Austrian government was a major mistake which Boltzmann quickly came to regret. He renounced the position in Berlin but the damage was already done.