Information From Sanskrit Rules to the Gene: Nine Scientists

Panini wrote the Ashtadhyayi, a grammar of Sanskrit in roughly four thousand rules with compact abbreviations and a strict ordering for which rule applies when several could. The atlas describes it as closer to an algorithm than to a descriptive list, and as generative, producing all and only the well formed sentences of the language. The century he worked in is still disputed, from the seventh to the fourth century BCE.

In 1936 Turing defined an abstract machine that reads and writes symbols on a tape according to a table of rules, and used it to prove that no general method can decide whether an arbitrary program will finish or loop forever. The same paper showed that one such machine can simulate any other, the theoretical basis for the general purpose computer.

Shannon showed in his 1937 master's thesis that electrical switching circuits could carry out logical operations using Boolean algebra. His 1948 paper A Mathematical Theory of Communication then founded information theory, defining the bit as its basic unit and entropy as a measure of a message's uncertainty, and setting the limits on compression and on reliable sending over a noisy channel.

On 16 December 1947 Bardeen, a theorist at Bell Labs, worked with the experimentalist Walter Brattain to demonstrate the first working point-contact transistor. He shared the 1956 Nobel Prize in Physics for it, and later won a second in 1972 for the BCS theory of superconductivity, the only person to date to win the Physics prize twice.

Brattain, an experimental physicist who joined Bell Labs in 1929, built the first point-contact transistor with Bardeen, working on the surface properties of semiconductors. It was a solid-state device that could amplify an electrical signal without the fragility, bulk or power draw of a vacuum tube.

Shockley led the Bell Labs solid-state physics group whose research direction produced the transistor, though he was not present for the 1947 demonstration, and he developed the more easily manufactured junction transistor in 1951. His Shockley Semiconductor Laboratory, whose staff left in 1957 and went on to found Fairchild Semiconductor and later Intel, is credited with helping make Silicon Valley. His later advocacy of eugenics was rejected by biologists and geneticists as pseudoscience.

The trail now turns from machines to living things. Crick, with James Watson, published the DNA double helix model in Nature in April 1953, and later worked on which triplets of DNA bases, called codons, correspond to which amino acids in a protein. That mapping from a sequence of bases to a protein is why the genetic code is called a code.

Watson moved to the Cavendish Laboratory at Cambridge in 1951 and worked with Crick on the structure of DNA. They shared the 1962 Nobel Prize in Physiology or Medicine with Maurice Wilkins. Watson led Cold Spring Harbor Laboratory from 1968 and helped direct the Human Genome Project at the National Institutes of Health from 1988 to 1992. In 2019 the laboratory stripped him of honorary titles after remarks linking race and intelligence.

Dawkins's 1976 book The Selfish Gene argued for a gene-centred view of evolution, in which the gene is the unit natural selection acts on and organisms are vehicles for its replication. The same book coined the word meme for a unit of cultural transmission modelled on the gene, carrying the idea of copied information beyond biology.