Steven Chu spoke at the University of Massachusetts Lowell on Wednesday. The acclaimed physicist was also named an honorary doctor of humane letters, and UMass Lowell Chancellor Jacquie Moloney and Vice Chancellor of Research and Innovation Julie Chen presented him with an honorary degree. Chu, who won the Nobel Prize in physics in 1997 and then served as US Secretary of Energy from 2009 to 2013, also delivered the university’s Tripathy Memorial Lecture as part of the event. Named for the late Sukant Tripathy, a UMass Lowell chemistry professor and provost, the program invites top researchers to the university to speak about important issues in science and technology. Chu spoke about climate change and clean energy.