## Proof

Mathematician Bernhard Riemann explains the importance of proofs in mathematics. He proves a theorem on stereographic projection.

## Fibration continued

The mathematician Heinz Hopf describes his "fibration". Using complex numbers he builds beautiful arrangements of circles in space.

## Fibration

The mathematician Heinz Hopf describes his "fibration". Using complex numbers he builds beautiful arrangements of circles in space.

## Complex Numbers continued

Mathematician Adrien Douady explains complex numbers. The square root of negative numbers is explained in simple terms. Transforming the plane, deform...

## Complex Numbers

Mathematician Adrien Douady explains complex numbers. The square root of negative numbers is explained in simple terms. Transforming the plane, deform...

## The fourth dimension continued

Mathematician Ludwig Schläfli talks to us about objects in the fourth dimension and shows us a procession of regular polyhedra in dimension 4, strange...

## The fourth dimension

Mathematician Ludwig Schläfli talks to us about objects in the fourth dimension and shows us a procession of regular polyhedra in dimension 4, strange...

## Dimension three

M. C. Escher tells the adventures of two-dimensional creatures who are trying to imagine three-dimensional objects.?

## Dimension 2

Hipparchus explains how two numbers can describe the position of a point on a sphere. He then explains stereographic projection: how can one draw a pi...