Everyone has learned of the **Pythagorean theorem** in maths class:

In a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides (a² + b² = c²).

A lesser known fact is that **Pythagoras**, the Greek mathematician who came up with the theorem, had a school where numbers were essentially worshipped. The school of Pythagoras were obsessed with whole numbers and their ratios, believing the universe was built around whole numbers. Their motto was “** All is number**”.

In 520BC, a mathematician named Hippasus was murdered by members of the school of Pythagoras, by being thrown off the side of a ship. Why did a group of scholars go as far as killing a fellow mathematician? The reason lies in a special number.

Hippasus raised an interesting question regarding the Pythagorean theorem. Imagine a square where each side is 1 unit long. What is the length of the diagonal?

Using the theorem a² + b² = c²: 1² + 1² = 2 = c². Ergo, **c = √2**. This does not appear to be so controversial. The Pythagoreans would reason that it was simply a ratio between two whole numbers, much like ½ or ¾.

But as they tried to quantify what this ratio was, a horrifying truth emerged – **no ratio between whole numbers could produce √2**. It is what we now call an ** irrational number**.

This was heresy – how can such a number exist in a universe built around whole numbers? The Pythagoreans would not allow this. Hippasus tried to argue that √2 was just as real a number as any other, but his attempts to propagate the knowledge of irrational numbers was quashed through murder.

Knowledge is power, but knowledge can also lead to tragedy.