A white cat plays with a ball in a box, with a skeleton cat in the same pose diagonally across from it.

Erwin Schrödinger: What is Life?

If parallel universes exist, there is one in which Eamon de Valera lived out his days as a maths teacher. In that universe, Erwin Schrödinger never came to Dublin, and probably never wrote What is Life?.

Erwin Schrödinger fled Berlin and Nazism in 1933, travelling to Oxford (where he heard he had won the Nobel Prize) and Princeton. The famous Schrödinger’s cat paradox appeared in his essay The present situation in quantum mechanics (1935), based on the Copenhagen Interpretation of quantum physics. A thought experiment where a cat sealed in a box either lived or died depending on whether a quantum event occurred, it seemed to suggest two universes, one with a dead cat and one with a living cat, existed in parallel until an observer saw whether the cat was alive or dead.

Erwin Schrödinger in 1933. Wikimedia, Public Domain.

Waiting for a visa from the British Home Office for a job in Edinburgh, Schrödinger returned to Austria to work in the University of Graz. He was there from 1936 to 1938, and by the time he got the visa and the job, the Anschluss had resulted in the Nazi party taking control in Austria. Schrödinger was dismissed from his job and told he would not be permitted to work abroad. He fled to Rome, writing from there to Eamon de Valera (then head of the League of Nations) who invited him to come to Dublin to work in the Institute for Advanced Studies, then being set up. Schrödinger arrived in the autumn of 19391

In Dublin, Schrödinger worked on electromagnetic theory, relativity and a new unified field theory. On 5th February 1943, he delivered the first in a series of lectures on “What is Life”. The lectures were published in 1944 as a short book, also called “What is Life?”, a view of life from a physicist’s point of view. This work did not break new ground but “gathered together several strands of research and stated his questions in a stark and provocative manner”2

The first chapter reaches the “naive physicist’s” conclusion that living being and the processes it experiences “must have an extremely ‘many-atomic’ structure and must be safeguarded against haphazard, ‘single-atomic’ events attaining too great importance.”3 However (as the heading says) this conclusion is wrong. In reproduction, development is controlled by the chromosomes. The chromosomes carry “genes”: “the hypothetical same material carrier of a definite hereditary feature” which are tiny 4

Schrödinger wondered how the molecules could carry this information, given the readiness of groups of atoms to become disordered (as predicted by the second law of thermodynamics.) “Schrödinger argued that the molecular material had to be an ‘aperiodic’ solid that had embedded in its structure a ‘miniature code.’”5 This aspect of his work was to be the most influential – “there can be no doubt that some of the key figures of 20th century science – James Watson, Francis Crick, Maurice Wilkins and others – were inspired to turn to biology by the general thrust of Schrödinger’s work”6

Schrödinger also suggested that “an important aspect of metabolism is that it represents the cell’s way of dealing with all the entropy that it cannot help but produce as it builds its internal order.”7 The cell keeps order by avoiding equilibrium: equilibrium (reaching a stable state) is death. This aspect of Schrödinger’s theory inspired others to work in the field of nonequilibrium thermodynamics, for example Prigogine who in turn influenced Irish scientist (and philosopher) J. D. Bernal8.

Schrödinger closes the book with pure philosophy: philosophical speculations on determinism, free will, and the mystery of human consciousness. The key question for him is9:

whether we cannot draw the correct, non-contradictory conclusion from the following two premises:
(i) My body functions as a pure mechanism according to the Laws of Nature.
(ii) Yet I know, by incontrovertible direct experience, that I am directing its motions, of which I foresee the
effects, that may be fateful and all-important, in which case I feel and take full responsibility for them.
The only possible inference from these two facts is, I think, that I -– I in the widest meaning of the word, that is to say, every conscious mind that has ever said or felt ‘I’ — am the person, if any, who controls the ‘motion of the atoms’ according to the Laws of Nature.

(Perhaps not the type of conclusion we would have imagined a lecture in de Valera’s Ireland reaching.) Schrödinger relates this concept of consciousness to Indian philosophy: “From the early great Upanishads the recognition…(the personal self equals the omnipresent, all-comprehending eternal self) was in Indian thought considered, far from being blasphemous, to represent the quintessence of deepest insight”9. He also identifies it with mystic thought and Schopenhauer. Schrödinger argues the idea of multiple consciousnesses arises due to the experienced relationship of the consciousness to a particular area of matter, the body. From that people assume there must be as many consciousness as bodies, leading to questions like, does the soul die with the body (a suggestion Schrödinger finds distasteful) or live without it (an idea, Schrödinger says, that forgets the original hypothesis underlying the idea of multiple consciousnesses.) Even sillier questions arise, says Schrödinger, such as whether dogs or women have souls, which throws the whole hypothesis into disrepute.

He concludes:

The only possible alternative is simply to keep to the immediate experience that consciousness is a singular of less is never which the plural is unknown; that there is only one thing and Even in the that what seems to be a plurality is merely a series of different personality aspects of this one thing

Schrödinger is, of course, not an Irish philosopher, but it is interesting that the one work related to philosophy he wrote in Ireland has affinities to the neo-Platonic idea of the One, or indeed the heresy of an Irish monk in the Carolingian Empire that only one soul exists. The 75th anniversary of the first lecture was celebrated in Dublin on 5th February 2018.

A white cat plays with a ball in a box, with a skeleton cat in the same pose diagonally across from it.

Featured Image: “Paradoja de el gato de Schrödinger” (The Paradox of Schrödinger’s cat). Luis.avila.epr/Wikimedia
(CC BY-SA 4.0).

Further Reading

Erwin Schrödinger (1940/2013) What is Life? (pdf online on whatislife.ie)

Matthew Cobb (2013) “What is life? The physicist who sparked a revolution in biology” Guardian (7 Feb 2013).


  1. J J O’Connor and E F Robertson (2003) “Erwin Rudolf Josef Alexander Schrödinger” in MacTutor History of Mathematics archive (online).
  2. Bruce Weber (2015) “Life” in Edward N. Zalta (ed.) The Stanford Encyclopedia of Philosophy (Spring 2015 Edition) url=. “Schrödinger’s What is Life?”.
  3. Erwin Schrödinger (1940/2013) What is Life? (pdf online on whatislife.ie), page 6.
  4. Schrödinger 1940/2013, p. 10.
  5. Bruce Weber (2015). “Schrödinger’s What is Life?”
  6. Matthew Cobb (2013) “What is life? The physicist who sparked a revolution in biology” Guardian (7 Feb 2013).
  7. Bruce Weber (2015). “Schrödinger’s What is Life?”
  8. Bruce Weber (2015). “Schrödinger’s Dual “Legacy”
  9. Schrödinger (1940/2013), p. 31
  10. Schrödinger (1940/2013), p. 31
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