Stephen Hawking is a scientist.
Physics ( from [ φυσική , phusikḗ ( epistḗmē ) , knowledge of nature ] , from φύσις phúsis `` nature '' ) is the natural science that involves the study of matter and its motion and behavior through space and time , along with related concepts such as energy and force . Stephen William Hawking , ( born 8 January 1942 ) is an English theoretical physicist , cosmologist , author and Director of Research at the Centre for Theoretical Cosmology within the University of Cambridge . Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize , explain and predict natural phenomena .