…there are times when I think I possibly am a slightly odd person.
Apocalypse from www.xkcd.com
It made no sense to me. I didn’t understand the point of the reference to the end of the world, I didn’t know why a math(s) department would be involved, I didn’t understand why lots of people would want to sign the same piece of paper, and I didn’t know who Paul Erdős was. This is, essentially, the platonic ideal of failing to get a joke.
So what would you do in this situation? Shrug your shoulders and move on to the next cartoon? Experience a twinge of regret that you’re not geeky enough to get the geek reference, then shrug your shoulders and move on? Not me. Oh, no. I saw it as a challenge.
I googled Mr Erdős, and read all the way through his Wikipedia entry. It seems that he was a cherishably eccentric man, so reading through it wasn’t as much of a struggle as it might have been. I learned that he was a mathematician, and that he was himself keen on geeky in-jokes – he used to refer to children as ‘epsilons’ because, to quote Wikipedia, in calculus ‘an arbitrarily small positive quantity is commonly denoted by that Greek letter’. This is doubtless the kind of thing that has them rolling in the aisles at mathematical conferences, but wouldn’t, I fear, go down all that well at the open mic night in your local comedy club.
In the process of reading through Mr Erdős’ entry, I also found out that he was noted for the large number of collaborators with whom he had worked, and that a concept called the Erdős Number had been developed in consequence. The Erdős Number is something like a mathematical version of the Six Degrees of Kevin Bacon game.* In fact, there would appear to be those who are upset that the concept of relatedness through collaboration is more popularly known with reference to Mr Bacon than Mr Erdős, although there are key differences.
The fundamental point of the Six Degrees game is to establish that every actor can be linked within at the most 6 moves to Kevin Bacon (i.e. actor 6 worked with actor 5, who worked with actor 4, who worked with actor 3, who worked with actor 2, who worked with actor 1, who worked with Kevin Bacon). The Erdős Number makes no such claim – there are mathematicians with an Erdős Number of ∞, indicating that they have no eligible connection with Mr Erdős – but is simply a standard way of identifying how closely related a mathematician is to Mr Erdős. (Erdős himself had an Erdős Number of 0; a mathematician who collaborated with him directly has an EN of 1; a mathematician who collaborates with someone who has an EN of 1 has an EN of 2 – and so on.) Erdős Numbers of up to 15 have been reported, which is substantially more than the six moves allowed in the Kevin Bacon game.**
In any case, low Erdős Numbers have become a highly desirable commodity. Wikipedia reports that opportunities to acquire one through a spurious ‘collaboration’ have been auctioned on eBay at least twice. Putting all of this information together allowed me finally to understand the joke in the cartoon.
The world is imminently to be destroyed, and this has had the effect of raising the dead from their graves. Hearing this, a mathematician dashes off a paper, gets all of their colleagues to sign it, then rushes to the cemetery in order to ask the recently reanimated Mr Erdős to also add his signature to the paper. In other words, we are being invited to laugh at the idea that a low Erdős Number is so important to mathematicians that they would choose to spend their final minutes seeking out a collaboration credit.
Anyway, having finally understood the joke, I feel forced to say, in deference to my own geekish pedantry, that the rules pertaining to Erdős Numbers seem to indicate that the research paper has to have been published. It seems unlikely, given the publication timescales for most academic journals, and the fact of the imminent destruction of the world, that there will be an opportunity to actually achieve the enhanced EN. I also note that the official lists seem only to be updated once every three years, which would seem to make securing widespread acknowledgement problematic.
If I had been thinking about a cartoon along these lines, I think I might have tried to envision alternative narrative scenarios – such as a plague of zombieism, or a version of a Frankenstein-style situation – which would have enabled the reanimation of Mr Erdős without threatening the continued existence of the planet…
…er…where am I? I’ve just had the weirdest dream. I thought I was Sheldon Cooper…
* – Actually, I’ve just noticed that the rollover text for the cartoon on xkcd.com makes reference to Mr Bacon.
** – The principle reason that the chains of connection between actors tend to be shorter than those between mathematicians is, of course, that acting is a far more collaborative process. With the rare exception of monologues, actors are required to spend their entire working lives collaborating. This is not usually the case for mathematicians.