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Niels Bohr Asks if Living Processes Could be Described in Terms of Pure Physics and Chemistry


In 1933 Danish physicist Niels Bohr delivered a lecture on Light and Life before the IIe Congrès International de la Lumière, an international congress of light therapists, meeting in Copenhagen. His lecture marks his first detailed attempt to apply concepts arising from quantum mechanics (particularly complementarity) to areas outside physics.

“Here, for the first time, Bohr raised a question that was to preoccupy him, off and on, until his death: Would it ever be possible to push the analysis of living processes to the limit where they can be described in terms of pure physics and chemistry?” (Pais, Niels Bohr's Times, 411, 441-42, quote from 442).

Bohr’s lecture may be viewed as one of the foundation stones of molecular biology, in that it inspired the young physicist Max Delbrück (who was in the audience when Bohr delivered it) to switch from physics to biology “to find out whether indeed there was anything to this point of view” (quoted in Pais, p. 442). In 1935, two years after hearing Bohr’s lecture, Delbrück and two other scientists published a paper on genetic mutations caused by x-ray irradiation, in which they concluded that the gene must be a molecule. The ideas expressed in that paper inspired Schrödinger to write his famous What is Life?, a work which in turn motivated Watson, Crick, Wilkins and other scientists to devote their careers to unraveling “the secret of the gene” (quoted in Moore, Schrödinger, p. 403). Delbrück himself became a leader of what was known as the “phage group” of bacterial geneticists; in 1969, he received a share of the Nobel Prize for physiology / medicine for describing the means by which living cells are infected with viruses. “It is fair to say that with Max [Delbrück], Bohr found his most influential philosophical disciple outside the domain of physics, in that through Max, Bohr provided one of the intellectual fountainheads for the development of 20th century biology” (quoted in Pais, p. 442).

Bohr's lecture was published in Danish as "Lys og liv," Naturens Verden 17 (1933) 49-59. It was published in English as "Light and Life," Nature 131 (March 25, 1933) 421-423, and it was also published in German.  The English version was issued as a separate pamphlet by the IIe Congrès International de la Lumière.

Judson, The Eighth Day of Creation, 32-35.

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