Bernal, John Desmond (buhr NAL) (1901-1971), an Irish-born physicist, made major contributions to X-ray crystallography. He also became known as the founding father of molecular biology.

Bernal was educated in English boarding schools and studied mathematics, chemistry, mineralogy, geology, and physics at Emmanuel College, Cambridge. On the strength of his derivation of 230 space groups using Hamilton quaternions, Bernal won a research position at the Royal Institution in the laboratory of William Henry Bragg. There his reputation as a crystallographer grew to match Bragg's. He created a diagram for interpreting X-ray photographs that became known as the Bernal chart.

In 1927, Bernal returned to Cambridge as assistant director of research in the department of crystallography. There he did groundbreaking work, taking X-ray photographs of biologically important molecules, amino acids, proteins, sterols, and nucleoproteins. Bernal's certainty that the physical structure of such molecules possessed the key to the origins of life was validated 20 years later by the work of James Dewey Watson and Francis H.C.Crick on the structure of DNA. Bernal thus inaugurated the field of molecular biology. In 1937, he moved to London and became professor of physics at Birkbeck College.

After the Nazis came to power in Germany, Bernal, a committed Marxist, became more politically active. As an adviser to the British government, he contributed to planning the invasion of Europe by calculating the condition of Normandy's beaches. Following the war, he became chairman of the Presidential Committee of the Communist-organized World Peace Council. He also returned to Birkbeck College and worked on the structure of liquids.

Bernal's books include The Social Function of Science (1939), a classic of its kind, and Science in History (1954).

A series of strokes beginning in 1963 left him barely able to move or speak, but his mental capacity was undiminished until his death.

Bernal's pupil Dorothy Crowfoot Hodgkin received a Nobel Prize in chemistry in 1964.