Louis Victor Pierre Raymond, 7th Duc de Broglie (/də ˈbroʊɡli/, also US: /də broʊˈɡliː, də ˈbrɔɪ/, French: [də bʁɔj] or [də bʁœj] ; 15 August 1892 – 19 March 1987) was a French physicist and aristocrat who made groundbreaking contributions to quantum theory. In his 1924 PhD thesis, he postulated the wave nature of electrons and suggested that all matter has wave properties. This concept is known as the de Broglie hypothesis, an example of wave–particle duality, and forms a central part of the theory of quantum mechanics.