quality:correction
Gravity

Dirac quantised the gravitational field. His work laid the foundations for canonical quantum gravity. In his 1959 lecture at the Lindau Meetings, Dirac discussed why gravitational waves have "physical significance". Dirac predicted gravitational waves would have well defined energy density in 1964. Dirac reintroduced the term " graviton " in a number of lectures in 1959, noting that the energy of the gravitational field should come in quanta.