## HLF

Atomic clocks are the best time keepers, but need to be kept incredibly cold. Paradoxically, the cooling is achieved by shining light on them.

Bitcoin is a digital currency that isn't regulated by any kind of central authority. The structure which allows this decentralisation is called blockchain. But how, and how well, does it work?

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

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

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

The pioneering mathematician talks about his work, computer science and artificial intelligence.

We talk to pioneering mathematician Stephen Cook, who came up with the concept of NP-complete problems, about his work, computer science, and artificial intelligence.

Want to understand chaos? Then have a look at Smale's famous horseshoe map.

Want to understand chaos? Then have a look at this famous brainchild of the mathematician Stephen Smale.