 Another important stimulus to his philosophical thinking was his encounter with the revolutionary new physics of the early 20th century. Bridgman’s concerns about the definition and meaning of scientific concepts were forged in the general climate of shock suffered by physicists at that time from a barrage of phenomena and theoretical ideas that were entirely alien to everyday expectations, culminating with quantum mechanics and its “Copenhagen” interpretation. In a popular article, Bridgman wrote: “if we sufficiently extend our range we shall find that nature is intrinsically and in its elements neither understandable nor subject to law” (1929, 444).