American theoretical physicist Dr. Ronald Mallett pours dry ice into a ring laser at a laboratory at the University of Connecticut on March 23, 2015.
Photographer: Scott Eisen/BloombergThe hour is late. His scientific papers were published years ago, filled with equations wrought by the energies of a younger man. But at 69, theoretical physicist Ron Mallett still goes to work every day to build a time machine based on his most elegant construct:
At the other end of the equation, he believes, is his father.