Simplify the following text for a Grade 9 native English-speaking person.
Original: In 1971 , Phelps moved to the Economics Department at Columbia University , which also included future Nobel prize winners William Vickrey and James J. Heckman ( future laureate Robert Mundell joined three years later ) , as well as Phoebus Dhrymes , Guillermo Calvo and John B. Taylor .
Simplified: In 1971 , Phelps moved to the Economics Department at Columbia University , where Nobel prize winners William Vickrey and James J. Heckman were studying . Nobel Prize winner Robert Mundell joined three years later , as well as Phoebus Dhrymes , Guillermo Calvo and John B. Taylor .