14 March 2011

When two small worlds collide

After she won the Oscar for Black Swan, a popular New York Times article about Portman discussed that she is a published scientific author. Other entertainers have had academic success, too.

Some of the discussion on Twitter pointed out that as an actor and published scientific author, Portman was one of the few people to have a finite Erdős–Bacon number.

The Bacon number is easier to explain: it derives from the movie trivia game “six degrees of Kevin Bacon.” You can connect Kevin Bacon to a large number of other actors in a surprisingly small number of steps.

For instance, take silent film star Lon Chaney, Senior. Even though Lon Chaney died in 1930, about 28 years before Bacon was born, the film world is so interconnected that it only takes three steps to link the two.

Lon Chaney was in While the City Sleeps (1928) with William H. O'Brien, who was in Judgment at Nuremberg (1961) with Maximilian Schell, who was in Telling Lies in America (1997) with Kevin Bacon.

The Erdős number is named after itinerant mathematician Paul Erdős. This number represents the close connections of the mathematical research community, and Erdős’s... unique approach to collaborations. He basically lived out of a suitcase much of his adult life.

I was fairly certain that, like Portman, I could claim to have a finite Erdős–Bacon number. I had previously calculated by Bacon number (three, the same as Lon Chaney!), but couldn’t figure out my Erdős number. I’d never collaborated with a mathematician!

I was finally able to crack my Erdős number, with the help of the American Mathematical Society’s Collaboration Distance tool. By randomly entering people I’d worked with, I discovered a link through my Ph.D. supervisor, Dorothy Paul! Dorothy co-authored a mathematical paper that arose from my doctoral work, modelling how digging might be coordinated.

D. H. Paul coauthored with Pauline van den Driessche, who coauthored with Donovan R. Hare, who coauthored with Noga Alon, who was a coauthored with... (wait for it!)

Paul Erdős!

Now knowing that my Erdős number is five, I can say that my Erdős–Bacon number is no more than eight.

Portman’s Erdős–Bacon number is six. Curse you, Portman! You win again!


Hodge A, Edwards R, Paul DH, van den Driessche P. 2006. Neuronal network models of phase separation between limb CPGs of digging sand crabs. Biological Cybernetics 95(1): 55–68. DOI: 10.1007/s00422-006-0065-9


Unknown said...

Congratulations on having a Erdos-Bacon number!. It would be cool (as you mentioned previously) if biologists had a Darwin or Mendel number. :(
I work with Drosophila and i think most Drosophila people can figure out a Morgan number. I think worm people do similarly try to trace their lineage to Sydney Brenner.

Zen Faulkes said...

You can kind of get a Darwin number if you count Thomas Henry Huxley as a colleague of Darwin. If you count Huxley as having a Darwin number of one, it's fairly easy to track a link to Darwin though things like NeuroTree.

Based on that, I have a Darwin number of 8, which I wrote about here. There’s a slightly shorter route in NeuroTree that gives me a Darwin number of 7, but I actually like the longer one better, because includes more neurobiologists and is a more traditional “supervisor to trainee” line of descent.

I’m sure some would dispute my Bacon number by arguing that extras don’t count. But too bad.

Bjørn Østman said...


My Erdös-Bacon number is also no more than 8.