Background: Murray Newton Rothbard (; March 2, 1926 - January 7, 1995) was an American heterodox economist of the Austrian School, a historian, and a political theorist whose writings and personal influence played a seminal role in the development of modern right-libertarianism. Rothbard was the founder and leading theoretician of anarcho-capitalism, a staunch advocate of historical revisionism, and a central figure in the twentieth-century American libertarian movement.
Context: Murray Rothbard's parents were David and Rae Rothbard, Jewish immigrants to the U.S. from Poland and Russia, respectively. David Rothbard was a chemist. Murray attended Birch Wathen, a private school in New York City. Rothbard later stated that he much preferred Birch Wathen to the "debasing and egalitarian public school system" he had previously attended in the Bronx.  Rothbard wrote of having grown up as a "right-winger" (adherent of the "Old Right") among friends and neighbors who were "communists or fellow-travelers." Rothbard characterized his immigrant father as an individualist who embraced the American values of minimal government, free enterprise, private property, and "a determination to rise by one's own merits". "[A]ll socialism seemed to me monstrously coercive and abhorrent."  He attended Columbia University, where he received a Bachelor of Arts degree in mathematics in 1945 and, eleven years later, his PhD in economics in 1956. The delay in receiving his PhD was due in part to conflict with his advisor, Joseph Dorfman, and in part to Arthur Burns rejecting his doctoral dissertation. Burns was a longtime friend of the Rothbard family and their neighbor at their Manhattan apartment building. It was only after Burns went on leave from the Columbia faculty to head President Eisenhower's Council of Economic Advisors that Rothbard's thesis was accepted and he received his doctorate. Rothbard later stated that all of his fellow students there were extreme leftists and that he was one of only two Republicans on the Columbia campus at the time.  During the 1940s Rothbard became acquainted with Frank Chodorov and read widely in libertarian-oriented works by Albert Jay Nock, Garet Garrett, Isabel Paterson, H. L. Mencken and others, as well as Austrian economist Ludwig von Mises. In the early 1950s, when Mises was teaching at the Wall Street division of New York University Business School, Rothbard attended Mises' unofficial seminar. Rothbard was greatly influenced by Mises' book, Human Action. Rothbard attracted the attention of the William Volker Fund, a group that provided financial backing to promote various "right-wing" ideologies in the 1950s and early 1960s. The Volker Fund paid Rothbard to write a textbook to explain Human Action in a form which could be used to introduce college undergraduates to Mises' views; a sample chapter he wrote on money and credit won Mises's approval. For ten years, Rothbard was paid a retainer by the Volker Fund, which designated him a "senior analyst." As Rothbard continued his work, he enlarged the project. The result was Rothbard's book Man, Economy, and State, published in 1962. Upon its publication, Mises praised Rothbard's work effusively.
Question: what did he do after his time in college?. Whats the answer?
Burns went on leave from the Columbia faculty to head President Eisenhower's Council of Economic Advisors