Humble Pi


Matt Parker




Date Reviewed:

November 22, 2020

he subtitle of this book is When Math Goes Wrong in the Real World (I read the hardcover edition, which apparently has a different subtitle than the paperback edition). It is an uneven collection of stories about mistakes and failures. Not all of these failures are actually due to math mistakes, more often it is human error, or math illiteracy.

I liked the chapter describing the problems with time. Did you know Julius Caesar decreed that a year shall be 365 days long, and every fourth year would contain one extra day? Caesar invented the leap year! I had no idea that concept originated in antiquity. 365.25 days is called a Julian year. But the actual year is slightly less, closer to 365.24 days, which is why leap years are skipped in years that end in 00, such as 1900 - unless the year that ends in 00 is also divisible by 400, in which case the leap day is included. A light year is the distance that light travels in one Julian year.

Some of the errors described involve units. When the Mars Orbiter famously crashed, failure analysis revealed that the cause was due to one team of engineers using English units, and the other team using metric units. Somehow this error was never detected until the satellite reached Mars, at which point the error resulted in a loss of the mission. Parker also includes a story about measuring the amount of fuel for an airliner, and again it is a matter of mistaken units.

Parker includes a story about the walkways failing in Kansas City mall; they collapsed and killed many people - but the collapse was because someone erroneously change the plan for the load-bearing bolts. There wasn't any math involved in the change of plans.

In another story, the windshield blows out of airliner in mid-flight because it was installed with the wrong bolts (the pilot was half-sucked out of the plane, but managed to survive and fly again!) The failure analysis is interesting, it shows how a series of unlikely mis-steps resulted in the incorrect bolts being placed into the windshield - fascinating post-mortem, but how is installing the wrong bolts a math error?

Some of the chapters seem like filler material. Who cares how many different ways items can be ordered off of a McDonald's menu? It is a simple factorial problem. Who doesn't know 256 is an important binary number? Parker slogs on and on about how some software programs are not capable of processing an infinite number of binary numbers. Yawn - Filler material. Who cares about flipping coins and counting how many consecutive 1s or 0s you will see? Filler material.

Is it a math error when the design of a bridge is altered, but the chief architect doesn't bother to recalculate the load? The bridge collapses and workers die.

Is it a math error when a radiation machine delivers a lethal dose of radiation to a cancer patient?

Parker includes a brief tale about the German police hunting for a mysterious female serial killer - her DNA kept showing up at different crime scenes. After an extensive search, the police discovered the female killer was a woman who worked in the factory that made the cotton swabs used to collect DNA evidence. An amusing story - but (for the umpteenth time) this is Parker giving us an example of math going wrong??

Parker seems to have a bit of a mean streak. An enthusiastic guy puts out a report that shows three megalithic sites in England form a perfect isosceles triangle. But since there are thousands of megalithic sites in England, there are bound to be a few that form a perfect triangle if you mine through the data diligently enough. To point out the error, Parker published a report that showed that he could find 3 Woolworth stores in England that form a perfect isosceles triangle - thereby proving Woolworth's are constructed by aliens. I am sure the Woolworth report embarrassed the poor fellow who put out the results of his megalithic site research. Parker breezily assures us it is all in good fun, but it is easy for him to say that.

I liked the book about math called The Joy of X more than Humble Pi.