He anticipated Cantor's later work with his paradox, which shows there are as many perfect square numbers as whole numbers.  He wrote a tract against Orazio Gassi that claimed comets were optical illusions, The Assayer, and proposed that the distance covered by an object accelerating at a constant rate was proportional to the square of time. One of his works recounts a discussion between Salviati,
He anticipated Cantor's later work with his paradox, which shows there are as many perfect square numbers as whole numbers.  He wrote a tract against Orazio Gassi that claimed comets were optical illusions, The Assayer, and proposed that the distance covered by an object accelerating at a constant rate was proportional to the square of time. One of his works recounts a discussion between Salviati, Sagredo, and Simplico, but fails to discuss the Tychonian system. For 10 points, identify this man whose Dialogue Concerning the Two Chief World Systems drew ire from the Church for its support of a heliocentric model of the universe, an early improver of and user of the telescope.
He anticipated Cantor's later work with his paradox, which shows there are as many perfect square numbers as whole numbers.  
Galileo Galilei