EDIT: I knew Feynman. I did a Google image search which suggested Ulam, and also linked to here which has the image and a caption. (http://www.lanl.gov/science/1663/december2009/)
EDIT: I knew Feynman. I did a Google image search which suggested Ulam, and also linked to here which has the image and a caption. (http://www.lanl.gov/science/1663/december2009/)