# 6 Degrees of Separation

Episode three of A Further Five Numbers, the BBC radio series presented by Simon Singh.

Six is often treated as 2x3, but has many characteristics of its own. Six is also the "pivot" of its divisors (1+2+3=6=1x2x3) and also the centre of the first five even numbers: 2, 4, 6, 8, 10. Six seems to have a pivoting action both mathematically and socially. How is it that everyone in the world can be linked through just six social ties? As Simon discovers, the concept of “six degrees of separation” emerged from a huge postal experiment conducted by the social psychologist Stanley Milgram in 1967. Milgram asked volunteers to send a package by mail to one of a hundred people chosen at random. But they could only send mail to people they knew on first name terms.

## Possibly related…

1. ### 6 Degrees of Separation

Episode three of A Further Five Numbers, the BBC radio series presented by Simon Singh.

Six is often treated as 2x3, but has many characteristics of its own. Six is also the "pivot" of its divisors (1 2 3=6=1x2x3) and also the centre of the first five even numbers: 2, 4, 6, 8, 10. Six seems to have a pivoting action both mathematically and socially. How is it that everyone in the world can be linked through just six social ties? As Simon discovers, the concept of “six degrees of separation” emerged from a huge postal experiment conducted by the social psychologist Stanley Milgram in 1967. Milgram asked volunteers to send a package by mail to one of a hundred people chosen at random. But they could only send mail to people they knew on first name terms.

2. ### The Number Four

Episode one of Another Five Numbers, the BBC radio series presented by Simon Singh.

Simon Singh’s journey begins with the number 4, which for over a century has fuelled one of the most elusive problems in mathematics: is it true that any map can be coloured with just 4 colours so that no two neighbouring countries have the same colour? This question has tested some of the most imaginative minds — including Lewis Carroll’s — and the eventual solution has aided the design of some of the world’s most complex air and road networks.

3. ### Game Theory

Episode five of Another Five Numbers, the BBC radio series presented by Simon Singh.

In 2000, the UK government received a windfall of around £23 billion from its auction of third generation (3G) mobile phone licences. This astronomical sum wasn’t the result of corporate bidders "losing their heads", but a careful strategy designed to maximise proceeds for the Treasury.