Widely regarded as one of the most influential physicists of the 20th Century, Nobel laureate and Caltech professor Richard P. Feynman will be honored on a 2005 U.S. postage commemorative stamp. The stamp will be unveiled locally at a celebration on Friday, May 20, at 5 p.m. in Ramo Auditorium on the California Institute of Technology campus. The public is invited to attend this free event. Caltech will offer a limited-edition special commemorative envelope bearing the four stamps that compose the American Scientists series, and a special cancellation stamp from the Feynman Station at Caltech. Stamps and cachets, as well as Feynman books and memorabilia, will be available for purchase.