Question: who proved that heavy and light objects fall at the same speed
Answer: In 1589 -- 92 , the Italian scientist Galileo Galilei ( then professor of mathematics at the University of Pisa ) is said to have dropped two spheres of different masses from the Leaning Tower of Pisa to demonstrate that their time of descent was independent of their mass , according to a biography by Galileo 's pupil Vincenzo Viviani , composed in 1654 and published in 1717 .