Hippasus was the student of Pythagoras who discovered the IRRATIONAL NUMBER.
What is IRRATIONAL NUMBER?
An IRRATIONAL NUMBER is a number that cannot be written as a fraction another side a rational number can be expressed as a simple fraction.
Story: Hippasus √2
According to one story, Hippasus was toying with the number √2, attempting to find the value or equivalent fraction. after some times he came to realized that no such fraction existed and √2 is an irrational number. Hippasus overjoyed by his discovery but Pythagos was not. Exsistance of irrational number brought Pythagoras theory into questionable as Pythagoras defined the universe in term of rational number.