IT'S THE hottest, newest game in Hollywood and top mathematicians are playing it, too. The new world record holder is a professor from Columbia University, and there is speculation that Gwyneth Paltrow is on the verge of becoming a major player who could steal the champion's crown. Welcome to the exclusive world of the Erdös-Bacon number game.
I became aware of the game last month, when I met Prof Dave Bayer at a New York diner. We were discussing something else, but he could not resist telling me about the Erdös-Bacon game, having just matched the world record.
The game has its origins in the Sixties and the work of Stanley Milgram, who showed that the world is a tightly knit community, because each person knows people, who know people, who know people, until the whole world is connected. He claimed that any two people in the world could be connected by six steps on average, giving rise to the expression "six degrees of separation".
The theory inspired a huge amount of scientific research, ranging from how to build a telephone network to the interconnectivity of brain cells, and including studies on the transmission of sexual diseases. But the most famous spin-off has been Six Degrees of Kevin Bacon, a game invented by three students at Albright College, Pennsylvania, which involves linking people to the actor via film appearances.
Building a bridge to Bacon can be done on the web, where there are specially designed databases with half a million actors. Most actors can reach Bacon within 3 links, and are said to have a Bacon number of 3. In fact, the average Bacon number is 2.920. But many stars have lower Bacon numbers. Keith Chegwin has a Bacon number of 2, because Cheggers was in House! with Miriam Margolyes, who was in Balto with Bacon.
Meanwhile, mathematicians have been working out their Erdös numbers. Paul Erdös wrote academic papers with a total of 502 co-authors, more than twice as many co-authors as any other mathematician. So if you wrote a paper with Erdös, then you have an Erdös number of 1, and if you wrote a paper with someone who wrote a paper with Erdös then you have an Erdös number of 2, and so on. There are 337,000 mathematicians who can be linked to Erdös in this way.
But recently, following a spate of mathematical films such as Good Will Hunting, an elite group of people have emerged, namely those who have appeared in films and written mathematical papers, and therefore qualify for Erdös-Bacon numbers. For a long time, the physicist Brian Greene had a clear lead with a score of 5. He appeared in Frequency with John Di Benedetto, who was in Sleepers with Bacon. And he wrote a paper with Shing-Tung Yau, who wrote a paper with Ronald Graham, who wrote a paper with Erdös. This gives a combined number of 2 + 3 = 5.
There were rumours that Erdös appeared in a film entitled p which would have given him an Erdös-Bacon number of 3, blowing away all competition. However, official sources can find no evidence for a movie credit for Erdös.
Brian Greene's only serious rival appeared this year, when Dave Bayer, mathematical consultant to A Beautiful Mind, was given a minor speaking role in the film, a scene known as the "pen ceremony". He is the third professor to lay down a pen before Russell Crowe.
Also in A Beautiful Mind was Rance Howard who appeared in Apollo 13 with Bacon, giving Bayer a Bacon number of 2, which he could add to his Erdös number of 3 to give a total of 5, matching Greene's record.
And now there is speculation about who will be next to set a new Erdös-Bacon record. Although most bets are on a mathematician achieving this, it is worth considering the possibility of a Hollywood star stealing the honour. Gwyneth Paltrow is about to appear at the Donmar Warehouse in Proof, a play involving mathematics.
She might be inspired to write a mathematical paper and, in theory, she could achieve an Erdös number of 2 - it is too late to get an Erdös number of 1 because Erdös died some years ago. Already she has a Bacon number of 2, having appeared in The Pallbearer with Greg Grunberg, who was in Hollow Man with the omnipresent Mr Bacon. This would give her a combined number of 4. If, however, she could star alongside Bacon, then she could achieve a combined number of 3.
The only actor who could beat 3 would be Bacon himself, who is in the privileged position of having a Bacon number of zero.
- Simon Singh, author of The Code Book, will appear at The Cheltenham Festival of Science, which runs from 22-26 May. For more information, see advert below; visit www.cheltenhamfestivals.co.uk or call box office: 01242 227979