It’s Pi Day on March 14, a date celebrated particularly in the schools and colleges of America. Why March 14? Because the date is “3.14” (if you follow the USA date format). In fact, it’s quite a vintage version of Pi Day this year because the date is actually 3.14.16, which is pi to five significant figures. Not as vintage as last year when, as Steven Strogatz pointed out, as the clock reached 9:26 and 56 seconds in the morning, we had attained pi to 10 significant figures: 3.141592656.
We don’t seem to make so much of it in Europe, which is a great pity since it highlights the importance of mathematics (and let’s face it, maths needs all the good press it can get). It may surprise you to learn that pi is not named after the well-known pastry-based savory but is in fact named after a Greek letter. The Greek mathematician Archimedes, who made an early estimate for the value of pi at between 22/7 and 223/71, never gave it a name, but the π symbol was first used by the Welsh mathematician William Jones in 1706. Confusion often arises because pies are usually circular and have a volume in which pi appears at least once. The pie in this picture for example has volume approximately: V= πr2(d+h/3).
To work out the calories in this pie, you need pi. But to work off the calories in this pie, you need an exercise bike. And no more pie.
Pi turns up in engineering in many places: volumes of circular tanks, the period of a pendulum, Stokes Law (spheres falling through liquids), buckling forces on pillars and pipes, flow rates and pumping tests.
Pi also turns up in many parts of probability theory. The most important distribution in probability is the Normal distribution (also called the Gaussian distribution) described by the equation: f(x) = 1/√(2π σ2) exp[-(x-μ)2/2σ2]. Almost everything that varies randomly will follow the shape of this equation (e.g. draw a histogram of the height of the kids in your school).
Bizarrely, pi also crops up in number theory. Guess what 1 + 1/22 + 1/32 + 1/42 +… is? It’s π2/6. I’ll spare you the proof. Connecting and proving all these facts about pi may sound like madness, but if you can, you’ll find the connections are a thing of beauty, like flicking on a light switch or solving a puzzle.
We as engineers appreciate more than most, that mathematics is the language underpinning all science. It is the bedrock of everything we at MWH do, every design, every cost-benefit calculation, every hydraulic model, every survey. You can’t calculate without mathematics. For us and our children, there are no shortcuts. Get yourself a solid grounding in mathematics and you open the door to a real and deeper understanding of the world and the universe it sits in.
Alec Erskine is a managing consultant with Hawskley Consulting a subsidiary of MWH Global. He is based out of the Edinburgh office.