FILE - In this Dec. 16, 2008 file photo, American physicist, and Nobel laureate Martin L. Perl, speaks at a Science Conclave at the Indian Institute of Information Technology in Allahabad, India. Standford University said Perl , who discovered a subatomic particle known as the tau lepton, died Tuesday, Sept. 30, 2014, at Stanford Hospital in Palo Alto, Calif.. Perl, He was 87. (AP Photo/Rajesh Kumar Singh, File)