## Articles

Resonant electromagnetic waves, created by lightning flashes, circle the Earth. Wim Hordijk explores the maths and shows how you can keep track with these phenomena.

We take the real numbers for granted, but what are they really?

Take a quick trip to the foundations of probability theory.

Need to find the least common multiple or greatest common divisor of two numbers? A billiard table of the right proportions holds the answers!

Randomness is surprisingly hard to define. Fortunately the mathematical language we use to describe it is beautifully well defined.

Symmetry is one of the two guiding principles in understanding probabilities – if different outcomes are equivalent they should have the same probability.

The second guiding principle in probability theory is more subtle – universality.