Puck Math

The Physics of Hockey
Alain Haché
Published by The Johns Hopkins University Press, 2002
ISBN 0801870712


I’ll admit it, I’m a bit of a math geek. I’ll also admit that I’m a bit of a sports geek. One look at the URL you’re at now should confirm that. One brief visit to the parent site of this blog, WashingtonHockey, will confirm that I don’t have the slightest shame about combining the two interests either. If I spot a chance to include a bit of regression analysis, or some economic theory to a hockey story, well, my day is made. Imagine my excitement, then, when my lovely girlfriend’s father sends me a book as a gift. Getting any book is a treat, but when it’s got the words "Physics" and "Hockey" both in the title, well, I almost made an honest woman out of her just to show him my appreciation!

Since I’m being honest here, I’ll flat out say that if you don’t like either physics or hockey you’ll hate the book. If you like hockey but can’t tell sin θ from Sins of the Father, you’ll struggle (unless you’re a young, hockey playing Canadian male in which case you’ll be glad to know that your chance of making it to the NHL is about 1 in 6,000). If you like physics but can’t tell a check from a Slovak, it’ll be interesting but nothing spectacular (unless you’re a young, non-hockey playing Canadian male in which case you need to consider the odds of making an NHL-equivalent salary if you stick with physics as a career). If you like both, though, this is a treat, and this review is for you.

You know physics, and you know hockey, so you’ve got a good understanding of the shooting motion. The wind-up, the swing, the release, the curvature of the stick, that’s all familiar. This book, however, explains all the motions and interactions involved in the process and there’s more than you might think. The same goes for goalie positioning, skating, accuracy, checking, and player quality. You can see how the author determines that Ray Bourque’s window of opportunity for a goal on a slapper from just inside the blue line, through traffic, with a screened goalie in a partial butterfly was 0.3° (aperture from 70 feet using Δθx = 2arctan (Δx/2d) as the determining formula for horizontal margin of error). Speaking of the butterfly, Haché uses Felix Potvin and Patrick Roy to demonstrate why that particular stance is so popular, while choosing Marty Brodeur for reaction times. He explains salaries as a function of probability, not relative or absolute quality (though I’d like to see him address that now that we’ve got a cap). Bobby Hull is the model in the discussion of shot selection in the crease. Jaromir Jagr shows off his skating power. The list goes on and on and on.

This book lives on my bedside table, with occasional forays to the bathroom bookshelf. I don’t pick it up every day, or even every week, but I never go very long without re-reading a chapter. I don’t play hockey, but I love to apply this kind of knowledge of physics to day to day activities, be it carrying things or playing golf. If you’ve got a puck-crazy friend who did pretty well in high school physics, get ‘em this book, they really don’t need yet another collection of crazy quotes from the penalty box.

Note: I am disappointed that, with all the academic vigor and attention to mathematical accuracy the author devotes, he described Mark Recchi giving "110% at every shift." That’s blatantly impossible. Dale Hunter, sure, but Recchi never gave more than 102% when I’ve seen him…