Erwin Schrödinger

• 1. Introduction

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  Erwin Schrödinger was born on the 12th of August 1887 in Vienna, and by the time he died on the 4th of January 1961, he had left behind an equation that altered how humanity understands the fabric of reality. He had also coined a phrase - quantum entanglement - that now anchors one of the most active frontiers in physics. And he had written a slim book about biology that, according to James D. Watson's own memoir, put Watson on the path to discovering the double helix structure of DNA.

  Yet Schrödinger spent much of his adult life fleeing. He fled Nazi Germany in 1933, was dismissed from his post in Graz in 1938, and eventually found a long-term home in Dublin only through a personal invitation from Ireland's Taoiseach. He shared a house with his wife and a second woman in an arrangement that cost him positions at both Oxford and Princeton. He died of tuberculosis, the same disease that had stalked him since the 1920s, in a Catholic cemetery in Alpbach despite having been an atheist his entire life.

  How does a man shaped by so much disorder write the most celebrated paper in twentieth-century physics? And what does it mean that the figure who gave us wave mechanics famously said he wished he had never had anything to do with the probability interpretation of quantum theory? Those questions run through everything that follows.

• 2. Vienna to the Trenches

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  Rudolf Schrödinger, Erwin's father, was a botanist; his maternal grandfather held a chair in chemistry at TU Wien. The household crossed religious lines - his father Catholic, his mother Lutheran - and his mother was of half English descent, which gave the young Schrödinger an advantage he would carry his whole life: English learned at home, outside school, through his British grandmother.

  At the University of Vienna from 1906 to 1910, he studied under Franz S. Exner and Friedrich Hasenöhrl, receiving his doctorate under Hasenöhrl in 1910. He also worked experimentally with Fritz Kohlrausch, and the following year became an assistant to Exner, completing his habilitation in 1914. That credential gave him the right to teach at a German-language university - a formal gate in the European academic system.

  Then the war arrived. From 1914 to 1918, Schrödinger served as a commissioned officer in the Austrian fortress artillery, posted across the Italian front at Gorizia, Duino, Sistiana, and Prosecco before returning to Vienna. The contrast is striking: a man who would later spend years meditating on consciousness and Eastern philosophy spent some of his most formative years directing artillery.

  In 1919, he performed what the source identifies as his last physical experiment, on coherent light, and made a deliberate pivot to purely theoretical work. It was the decision that would make him famous.

• 3. The Wave Equation

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  In January 1926, Schrödinger published a paper in Annalen der Physik titled "Quantisierung als Eigenwertproblem" - Quantization as an Eigenvalue Problem - and physics changed. The paper derived the wave equation for time-independent systems and showed it reproduced the correct energy values for a hydrogen-like atom. That first paper was followed by a second, submitted just four weeks later, which solved the quantum harmonic oscillator, the rigid rotor, and the diatomic molecule in a single paper and offered a new derivation of the equation itself.

  A third paper, published in May 1926, showed that his wave mechanics was mathematically equivalent to Werner Heisenberg's matrix mechanics. A fourth paper extended the method to time-varying systems such as scattering problems; in it, Schrödinger introduced a complex solution to the wave equation specifically to prevent the emergence of fourth- and sixth-order differential equations, reducing the order to one.

  The intellectual roots of this burst ran back to earlier work. In autumn 1922, Schrödinger had analyzed electron orbits geometrically using methods developed by his friend Hermann Weyl. That analysis, which tied quantum orbits to specific geometric properties, was a step toward predicting features of wave mechanics. He had also been drawn in earlier years to Exner's idea of the statistical nature of conservation laws.

  There is a biographical detail that matters here: Schrödinger was suffering from tuberculosis during this period and spent time at a sanatorium in Arosa, Switzerland. It was at Arosa that he formulated the wave equation. The location - a Alpine retreat for the ill - was where one of the most consequential equations of the twentieth century took shape.

• 4. Entanglement and the Cat

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  In 1935, Schrödinger was in the middle of the most turbulent stretch of his professional life, having just left Oxford and not yet secured a stable position. It was in this period, after extensive correspondence with Albert Einstein, that he produced the two ideas most associated with his name in popular science.

  Building on a paper by Einstein, Boris Podolsky, and Nathan Rosen - the thought-experiment now called the EPR paradox - Schrödinger published a paper that gave formal shape to what he himself named quantum entanglement. He described this phenomenon as "the one that enforces its entire departure from classical lines of thought." The coinage of that term in 1935 is credited to him specifically.

  The Schrödinger's cat paradox was devised in the same year. He intended it as a critique - a way of exposing what he found absurd in the Copenhagen interpretation held by Niels Bohr and Werner Heisenberg. He reportedly complained to students that the Göttingen physicists were using his beautiful wave mechanics for calculating what he called, in notably earthy language, their "shitty matrix elements."

  His discomfort ran deeper than professional rivalry. On the probability interpretation of quantum mechanics, he wrote: "I don't like it, and I'm sorry I ever had anything to do with it." By the 1950s, he had moved further still, arguing that the different terms of a quantum superposition are "not alternatives but all really happen simultaneously" - an anticipation of what would later be called the many-worlds interpretation.

• 5. Dublin and What Is Life

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  In 1939, Éamon de Valera, Ireland's Taoiseach, sent Schrödinger a personal invitation to come to Dublin. The following year, Schrödinger became the founding Director of the School of Theoretical Physics at the newly established Dublin Institute for Advanced Studies, a post he held until 1955. He settled modestly on Kincora Road in Clontarf, and a plaque has since been placed at that address as well as at his workplace in Merrion Square.

  Schrödinger felt a genuine connection to Ireland. In October 1940, he told a writer from the Irish Press that he believed in a "deeper connection" between Austrians and Celts, citing place names in the Austrian Alps as possible Celtic survivals. He became a naturalized Irish citizen in 1948 while also keeping his Austrian citizenship.

  In 1943, he gave three major lectures at Trinity College Dublin. Those lectures gave rise to annual conferences held in his name, and College buildings were named after him. The following year, 1944, he published What Is Life?, which introduced the concept of negentropy and speculated that genetic information might be stored in a complex molecule.

  The reach of that book proved extraordinary. James D. Watson, in his memoir DNA, the Secret of Life, named What Is Life? as the inspiration that led him to research the gene, which in turn contributed to the discovery of the DNA double helix structure in 1953. Francis Crick made a parallel acknowledgment in his autobiographical book What Mad Pursuit, describing how Schrödinger's speculations about molecular information storage influenced his own path. A manuscript Schrödinger wrote for the 1955 edition of The King's Hospital boarding school's Blue Coat publication, titled "Fragment from an unpublished dialogue of Galileo," resurfaced at that Dublin school years later.

• 6. Philosophy and Consciousness

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  Arthur Schopenhauer and Baruch Spinoza shaped Schrödinger's philosophical sensibility. In his 1956 lecture "Mind and Matter", he opened with words that directly echo the first line of Schopenhauer's main work: "The world extended in space and time is but our representation."

  Schopenhauer also served as Schrödinger's path into Indian philosophy, specifically the Upanishads and the Advaita Vedanta tradition. Schrödinger expressed sympathy for the principle of tat tvam asi, and once posed a question that reads almost like a physicist's formulation of a theological problem: "If the world is indeed created by our act of observation, there should be billions of such worlds, one for each of us. How come your world and my world are the same?"

  His answer, which he drew from the Upanishads, was the doctrine of a single underlying mind. He wrote: "Their multiplicity is only apparent, in truth there is only one mind." On consciousness itself he held a position he stated plainly: "Consciousness cannot be accounted for in physical terms. For consciousness is absolutely fundamental."

  Some commentators have argued that a non-dualist Vedanta-like framework served as a broad inspiration for his theoretical physics, not merely as a personal conviction. Schrödinger himself was careful to note that Eastern ideas did not always fit with empirical approaches to natural philosophy, an acknowledgment of the tension he held between mysticism and scientific method. His later writings also contain elements resembling the modal interpretation developed by Bas van Fraassen, suggesting that the philosophical threads he wove were still being picked up by others long after his death.

• 7. Abuse and Legacy

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  Around 1926, when Schrödinger was 39, he began tutoring a 14-year-old girl named Itha Junger, known as Ithi. Walter Moore's 1989 biography of Schrödinger describes the tutoring sessions as including petting and cuddling, and states that not long after her seventeenth birthday the two became lovers. In 1932, when Ithi was 20, she became pregnant; Moore records that Schrödinger tried to persuade her to keep the child but did not offer to divorce his wife, and that Ithi arranged for an abortion.

  Moore describes Schrödinger as having a Lolita complex and quotes from his diary an attraction to women he characterized as close to "the preferred springs of nature." Carlo Rovelli, in his book Helgoland, writes that Schrödinger "made no secret of his fascination with preadolescent girls" and describes him fathering children from two additional women during his time in Ireland - one identified in a Der Standard article as 26 years old, the other a married political activist of unknown age. Moore's book also describes Schrödinger's infatuation with a twelve-year-old girl, Barbara MacEntee, while he was in Dublin; he stopped his attentions after what the source calls a "serious word" from someone.

  A 2021 Irish Times article described Schrödinger as "a serial abuser whose behaviour fitted the profile of a paedophile in the widely understood sense of that term." In January 2022, the physics department of Trinity College Dublin announced it would recommend renaming a lecture theatre that had carried Schrödinger's name since the 1990s, removing his portrait, and considering the renaming of an eponymous lecture series.

  Schrödinger's grandson Terry Rudolph has followed him into quantum physics and teaches at Imperial College London. The Erwin Schrödinger International Institute for Mathematical Physics was founded in Vienna in 1992. The philosophical questions posed by Schrödinger's cat remain actively debated in physics and philosophy today, while the wave equation he derived in a Swiss sanatorium during an illness has never stopped being used.