The macroscopic theory of van der Waals theory has many experimental validations. Among which, some of the most notable ones are Derjaguin (1960); Derjaguin, Abrikosova and Lifshitz (1956) and Israelachvili and Tabor (1973), who measured the balance of forces between macroscopic bodies of glass, or glass and mica; Haydon and Taylor (1968), who measured the forces across bilayers by measuring their contact angle; and lastly Shih and Parsegian (1975), who investigated Van der Waals potentials between heavy alkali-metal atoms and gold surfaces using atomic-beam-deflection.