Alexander Moszkowski (15 January 1851 – 26 September 1934) was a German satirist, writer and philosopher of Polish-Jewish descent. He was the brother of the composer and pianist Moritz Moszkowski. He was a friend of many celebrities in Berlin, among them the theoretical physicist Albert Einstein, about whom he was the first to publish a book in the summer of 1920 and consequently popularize the theory of relativity. In his autobiography he wrote: "At the beginning of the 20th century the question of the conceivability of other worlds with modified physics and mathematics will be highly employed."