CultureLab

Sherlock Holmes averts world war using mathematics

Jessica Hamzelou, contributor

(Image: Warner Br/Everett/Rex Features )

An evil mastermind is set on bringing about global war. Only one man can stop him: Sherlock Holmes, with the help of  his partner in crime-solving Dr Watson. But in the latest Holmes flick, Sherlock Holmes: A game of shadows,  they don’t just need their trusty revolvers and Holmes’s trademark prescient fight scenes, they also need to grasp some mathematics.

The villain is Holmes’s nemesis,  James Moriarty, a professor of mathematics and all-around evil genius. In the book The Final Problem, he is described by Holmes himself as “a genius, a philosopher, an abstract thinker. He has a brain of the first order.”

But behind the wit of the character in the film lies the mathematical know-how of a team at the University of Oxford. Alain Goriely and Derek Moulton at Oxford’s Mathematical Institute have been hard at work behind the scenes helping to formulate a believable mathematical villain.

Initially, the filmmakers approached the mathematicians to ask them to fill Moriarty’s blackboard with equations. Not only did they have to be real, they had to be historically accurate, based on a 19th-century understanding of the field.

“When we did the equations on the blackboard, [the film-makers] got excited,” says Goriely. “Although they were quite secretive about the story, they told us that Moriarty was a mathematics professor and that they wanted us to help them add more meat to the script, which was a little dumb and mostly incorrect.”

Goriely and Moulton ended up going beyond script-tweaking to develop a secret code from scratch that Moriarty uses in the film to send messages around a Europe on the brink of the war he is conniving.

But how does one get into the mindset of a fictional evil genius from the 19th century? Unfortunately, Arthur Conan Doyle’s books were of limited help, offering sparse details on Moriarty’s interests, Goriely says. “We do know that the character wrote two books - one on binomial theorem and one titled The Dynamics of an Asteroid.”

To create a convincing code, the team started from the binomial theorem. “Binomial theorem is linked to Pascal’s triangle, so we devised a secret code based on that,” says Goriely.

The code is hidden in Moriarty’s red pocketbook, which is filled with numbers. The numbers signal to the reader first which Fibonacci p-code - a way to take digits from Pascal’s triangle - to use. This supplies another list of numbers, which are used to indicate which page, line and words from a book to look up. Goriely reckons his code is spot on for the character. “Moriarty was obsessed with Pascal’s triangle and Fibonacci’s codes,” he says.

The pair also wrote an entire lecture for Moriarty based on his interests in celestial dynamics. “I used elements of maths from celestial mechanics at the end of the 19th century,” says Goriely. “It was a very hot topic at the time.”

The lecture discusses the n-body problem - a mathematical problem that considers how moving celestial bodies interact with each other as a result of their gravitational energy. Moriarty would have likely had a particular interest in the theory, given its potential implications for weaponry, says Goriely. “If you could build a missile and throw it out of the atmosphere, it could re-enter with an asteroid-like impact. It would be brought back by gravitational forces,” he says.

While a disguised Holmes might have been party to the entirety of the lecture, sadly only the smallest of snippets made the final cut for the audience’s edification. And while Holmes’s fleeting glance of Moriarty’s blackboard proved key to his later success in foiling the professor’s evil plans, even the most beady-eyed mathematician watching the film will find such a feat tricky. But perhaps therein lies the attraction of Sherlock Holmes and his amazing powers of deduction.

http://www.newscientist.com/