This course of lectures will elucidate the notion of infinity in mathematics, natural sciences, philosophy, and theology by means of the historical evolution from the ancient world to modern times along with biographical details of life and works of leading scholars.

Very large numbers. How many sand grains are necessary to fill the universe? Measurable infinity. How much paint is required to paint an infinite area? Infinity minus infinity can (sometimes) be calculated. How long will it take to add 1 + 1/2 + 1/3 + ... up to 100? The sum of all natural numbers. Irrational and transcendental numbers. How many digits of p are known?

Atoms, elementary particles, quarks - and so on ? How big is the universe? Why is it dark in the night? The development of the universe from the beginning until ... When did the sun begin to shine? How long will it continue? Cosmic disasters. Is there an end of time? Will life last in eternity?

Philosophical and religious opinions about the infinite. Can God be proven to exist? Is God infinite? Can God make a stone so heavy that he cannot lift it?

Logical paradoxes. Zenon's arrow that never arrives at the aim. The tortoise of Achilles. The liar-paradox. The barber-paradox. Different degrees of infinity. Transfinite cardinal numbers. "Numbers" that never can be used.