Aside, of course, from the cat, perhaps the image most closely associated with Austrian physicist Erwin Schrödinger is that of a box. After all, in his famous quantum thought experiment, a closed box is what hides the hypothetical cat from the world, keeping the feline's fate unknown until it is opened.
Cruelly, within the box a Geiger counter sensitive to the decay of a radioactive sample is rigged to trigger the smashing of a vial of poison — in which case the tabby would be toast. However, according to the orthodox view, the sample would be in a mixed quantum state of decayed and not decayed, until the box is open and an observer takes a measurement. Similarly, the cat would be in a blended state (as Schrödinger put it, apologetically) of dead and alive.
Savvy students of physics know of another box associated with Schrödinger. One of the simplest solutions of his Nobel Prize-winning wave equation is that of a particle in a box. Unlike, say, a marble in a cigar box, whose exact location can be determined precisely, such a quantum particle is described by a smeared-out probability wave. The exercise brilliantly shows how uncertainty rules subatomic physics.
Schrödinger's motives, in many cases, were something like a black box. He could be as contradictory as his cat. Historians have trouble understanding, for example, why he bravely left Nazi Germany in 1933, effectively denouncing the regime, but then later, living in Austria after its annexation by the Nazis, tried to cozy up to the same evil government. He also had much trouble deciding between the many women in his life — at one point effectively having two wives — but that's another story.
Perhaps the biggest clue as to what motivated Schrödinger is his enormous box of collected correspondence, personal notes and other material, deposited in the Austrian Central Library, associated with the University of Vienna. It weighs more than 200 pounds. One would think that an archival box would generate little controversy. Think again.
Schrödinger died in January 1961, leaving one official heir: his wife Anny. She had been barren. However, he had offspring through other women. His children include a daughter, Ruth Braunizer, who was born to Hilde March (the aforementioned "second wife"). Ruth and her husband, Arnulf, live in the quaint Austrian village of Alpbach.
In 1963, Anny was visited by the noted philosopher and historian of science Thomas Kuhn, best known for his theory of paradigm shifts. Kuhn interviewed her about her late husband's life and asked permission for access to his box of materials. She granted him the right to copy the materials for research purposes, making them available to historians worldwide. When he was finished his archival work, he deposited the box with the University. Anny died in 1965, apparently never asking for the materials back. With her death, Ruth became the sole heiress to Schrödinger's estate.
Sometime in the 1980s, Ruth and Arnulf became aware of the box and began to look into its ownership. In 2006, they formally requested the return of the materials from the university. Both sides hired lawyers and began a legal skirmish. Suddenly, the fate of the historic treasure trove became as uncertain as that of the cat.
Eventually, the two sides agreed on the need to make Schrödinger's materials as accessible as possible, whether in Alpbach or Vienna. Honoring Schrödinger's contributions to science would be in the best interests of both the family and the university. From that point on, negotiations centered on the ideal way to make the contents of the box available and properly recognized.
Resolving a mixed quantum system, as we've seen, requires observers, for which the United Nations is well-known. In 2014, Schrödinger's legacy was deemed important enough to qualify as a UNESCO World Heritage Site. A ceremony was held in which Ruth, Arnulf and Schrödinger's granddaughter Verena Tomasik participated. As long last, the box had a clear owner: the world.
The family and university hope that the result of all this will be greater publicity for Schrödinger's other contributions, aside from his cat thought experiment and his wave equation. He published works in the fields of biology, cosmology, philosophy, religion, classical studies and many others.
As one example of his lesser-known contributions, in his book What is Life?, he proposed that the blueprint of life is an aperiodic crystal — a suggestion that helped motivate James Watson and Francis Crick to search for what became known as DNA.
Such a talented thinker should not be boxed in. It is high time to move beyond the box and recognize Schrödinger's valuable legacy.
Paul Halpern is a physics professor at the University of the Sciences in Philadelphia. He's the author several books, the most recent titled Einstein's Dice and Schrödinger's Cat: How Two Great Minds Battled Quantum Randomness to Create a Unified Theory of Physics. You can find him on Twitter here: @phalpern