He once calculated the number of grains of sand needed to fill the entire  universe. Born in 287 BC to the astronomer Phidias, he spent his youth in  Egypt learning mathematics. For ten points, who was this inventor of the  planetarium and discoverer of a principle stating that the force required to
He once calculated the number of grains of sand needed to fill the entire  universe. Born in 287 BC to the astronomer Phidias, he spent his youth in  Egypt learning mathematics. For ten points, who was this inventor of the  planetarium and discoverer of a principle stating that the force required to  buoy a solid body is equal to the weight of liquid that it displaces?
He once calculated the number of grains of sand needed to fill the entire  universe.
Archimedes