What is Life?

In 1943 the Nobel Prize-winning physicist Erwin Schrӧdinger (1887-1961) delivered three ground-breaking public lectures entitled 'What is Life?' at Trinity College Dublin. These lectures had an important impact on the future direction of biology.

In 2018 Trinity College Dublin is commemorating the 75th anniversary of the lectures with a major international conference, 'Schrödinger at 75: the future of Biology'. The Library has curated this exhibition which focusses on Schrӧdinger’s experiences in Dublin, and highlights other important collections of scientific interest.

Schrödinger's three public lectures under the collective title 'What is Life?' were the statutory DIAS lectures for 1943 and were delivered in the Physics lecture theatre at Trinity College Dublin. The lectures, which were published the following year, inspired a generation of biologists and directly influenced Francis Crick and James Watson in their work on DNA. This first edition was inscribed by Schrödinger to his friend Albert McConnell (1903-1993), Professor of Natural Philosophy and later Provost of Trinity College Dublin.

At the outbreak of the Second World War, Schrödinger, an outspoken critic of the Nazi regime, was dismissed from his position at the University of Graz in Austria and fled the country as a refugee. He was invited to Ireland by Taoiseach Éamon de Valera to become Director of the Dublin Institute for Advanced Studies (DIAS).

One of the reasons Schrödinger chose to come to Dublin was the chance to walk in the footsteps of one of his heroes, Sir William Rowan Hamilton (1805-1865), one of Ireland’s most renowned scientists. Hamilton’s work was of major importance to physics, and his reformulation of Newtonian mechanics - now called Hamiltonian mechanics - was crucial to the development of quantum mechanics. His discoveries have been used by countless scientists including both Schrödinger and Stephen Hawking (1942-2018). The Library of Trinity College Dublin holds the vast archive of Hamilton’s personal and professional papers.

These notes form part of Hamilton’s work on a ‘theory of system of Rays’, a topic which had occupied him since his undergraduate days at Trinity College. During the course of his work on this subject in the October of 1832 he predicted ‘Conical refraction’, which was then verified during experiments by Humphrey Lloyd, Professor of Natural and Experimental Philosophy, three months later. This announcement electrified the scientific community and awards followed: in 1835 Hamilton was awarded the Royal Medal of the Royal Society, along with Michael Faraday, and was also knighted by the Lord Lieutenant of Ireland in the Long Room of the Library of Trinity College Dublin.

Following on from his work on rays, in his late twenties Hamilton began to extend his thinking to mechanics, drawing an analogy between the path of a ray of light and the path of a moving body. In this paper, he rewrote Newton's laws of motion in a general way by expressing the energy of mechanical systems as special variables. The energy, when expressed in this way, is called ‘the Hamiltonian’. Hamiltonians were crucial to Schrödinger’s work and to the development of quantum mechanics.

Hamilton made numerous advances in the field of mathematics, but is perhaps most famous for the development of Quaternions, the mathematical notation for representing orientations and rotations of objects in three dimensions. Quaternions are essential for calculating orbital rotation in space flight; they are routinely employed by NASA, and are also relied upon by the computer gaming industry.
This tiny notebook contains Hamilton’s earliest surviving working-out of the Quaternion equation. As he recounted to Peter Guthrie Tait in a letter of 15 October 1858, ‘[I] felt the galvanic circuit of thought close; and the sparks which fell from it were the fundamental equations between i, j, k; exactly such as I have used them ever since. I pulled out on the spot a pocket-book, which still exists, and made an entry’.

The first ‘written’ record of the Quaternion equation was a fugitive piece of graffiti scratched by Hamilton on Broome Bridge in Dublin. In this letter, Hamilton recounts the circumstances around his discovery on 16 October 1843, ‘which happened to be a Monday, and a council day of the Royal Irish Academy – I was walking in to attend and preside, and your mother was walking with me, along the Royal Canal...yet an under-current of thought was going on in my mind, which gave at last a result, whereof it is not too much to say that I felt at once the importance...nor could I resist – unphilosophical as it may have been – to cut with a knife on a stone of Brougham Bridge, as we passed it, the fundamental formula...but of course, as an inscription, has long since mouldered away’.
Although the inscription degraded within Hamilton’s lifetime the site is now commemorated with a plaque.

Gathered around President Douglas Hyde (1860-1949) (in wheelchair) are Schrödinger, Kathleen Lonsdale, Éamon de Valera and Max Born.
Kathleen Lonsdale née Yardley (1903-1971) was born in Newbridge, Co Kildare and made a major contribution to the field of crystallography. A quaker and committed pacifist, Lonsdale was imprisoned for a month in Holloway prison in London for refusing to undertake mandatory war duties during the World War II. She subsequently became a lifelong campaigner for prison reform and a regular visitor to women’s prisons. She was one of the first women to be elected fellow of the Royal Society in 1945, the first Professor of Chemistry at University College London in 1949, was appointed a Dame Commander of the order of the British Empire in 1956 and elected the first woman president of the Association for the Advancement of Science (BAAS) in 1968.

Albert McConnell and Schrödinger were close friends and colleagues at DIAS and in this draft memoir McConnell describes him as the ‘scientific heir of Sir William Rowan Hamilton’.

This letter is from Ernest Walton to Professor E C Pollard, Department of Biophysics, Pennsylvania State University, who had requested Walton’s reminiscences of Schrödinger. Walton replies with memories of his ‘relaxed’ dress sense and musings on genetics.

Ernest Walton (1903-1995) graduated in maths and physics from Trinity College Dublin in 1926 and undertook postgraduate study in the Cavendish Laboratory in Cambridge under Ernest Rutherford. Working with John Cockcroft (1897-1967), he successfully split the nucleus of an atom in April 1932. They were subsequently jointly awarded the Nobel Prize in 1951 for ‘their pioneering work on the transmission of atomic nuclei by artificially accelerated atomic particles’.
Walton returned to Trinity College in 1934 where he became Professor of Natural and Experimental Philosophy. He was well known for his personal integrity, his compelling lectures and his commitment to the improvement of the standards of science education in Ireland.
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Walton met his future wife [Winifred] Freda Wilson when they were both in school in the Methodist College Belfast. They were engaged to be married during the time that Walton was in Cambridge and corresponded very frequently. This is the first letter that Walton sent to his fiancée after the successful experiment which occurred on 14 April 1932: ‘Cockcroft and I made what is in all probability a very important discovery in the lab … It opens up a whole new field of work which may go a long way towards elucidating the structure of the nucleus of the atom’.

During the 1930s the Cavendish Laboratory in Cambridge expected their research students to be economical in the setting up of their experiments. Walton was both meticulous in his working methods and gifted with his hands; it was he, Cockcroft and another postgraduate, Mark Oliphant, who devised much of the physical apparatus for their experimental work. This photograph shows Walton in the observation hut beneath the accelerating tube of the Cockcroft-Walton machine which could achieve voltages of up to 700Kv.

In 1951 the Nobel Prize for physics was awarded jointly to Ernest Walton and John Cockcroft ‘for their pioneering work on the transmutation of atomic nuclei by artificially accelerated atomic particles'. In 1993 he presented his Nobel medal and citation to the Library of Trinity College Dublin along with his personal and scientific papers

The scientific and mathematical communities have gathered on a number of occasions to celebrate the legacy and achievements of the ‘What is life?’ lectures, which have in turn sparked further important research. The events have attracted other ‘game changers’ in their respective fields such as Stephen Hawking who came to Dublin for the 40th anniversary commemorations in 1983, and Roger Penrose, Manfred Eigen and Jared Diamond in 1993.

Photograph of Professor Lochlainn O’Raifeartaigh, Senior Professor at DIAS, Professor Stephen Hawking and Professor Ernest Walton at the Schrödinger Memorial Symposium at the Dublin Institute of Advanced Studies in 1983.

Schrödinger’s years in Dublin left a lasting impression on the city and there is a lingering fascination with his experiences here. The idea of ‘Schrödinger as Dubliner’ has proved to be an inspiration for many artistic works, from novels to poetry and musicals.
Schrödinger appears as a character in the Rough Magic Theatre Company production of the musical Improbable Frequency by Arthur Riordan and Bell Helicopter, which was directed by Lynne Parker. Set in Dublin during World War II it examines Ireland’s neutrality through the bizarre range of European intellectuals assembled in Dublin at that time, bringing together the poet John Betjeman (1906-1984), the journalist Myles na gCopaleen/Flann O’Brien (1911-1966) and Schrödinger in a musical satire extravaganza