Humble Pi (5B)

Date: 09/02/2023

Good morning, everyone. I am Chan Chi Wai from 5B. Today I’m going to share a book named Humble Pi. The book is not about pi, but what happens when math goes wrong in the real world. Math is all around our world. Everything, including time, shape, statistics and engineering, requires math. However, mathematical mistakes appear everywhere too, from small problems like rounding off errors of unemployment to larger problems like using a wrong bolt to fix a plane. The book also features several mistakes for readers’ investigation.

 Among these examples, the story of The Millennium Bridge, also known as The Wobbly Bridge, gives me the greatest impression. It is about the miscalculation of the bridge’s swinging period. Bridges are not like houses or walls. They are suspended in the air. This makes it important for the bridges to be strong. However, in the case of The Millennium Bridge, there were only a few steel ropes to support it. Just after the bridge’s opening, it began to swing greatly side to side as crowds were using the bridge. At last, the bridge was forced to close after the second day of its opening and wasn’t reopened for the next two years due to this accident.

 You may wonder, what made the bridge swing so badly? The answer is resonance. The engineers mistakenly tuned the bridge to swing side to side at around 1 Hz, which is coincidentally the same as people’s walking pace. Supposedly, all the people would walk on the bridge at different paces and the sideway resonance would only be a problem if enough people walked perfectly in sync. As it turned out, because of a feedback loop, people were actually stepping in synchronization, which caused the bridge to move more vigorously. As a result, people’s footsteps became in sync. With more than 167 people on the bridge, there was enough force to make the bridge wobble and cause this hazard. This is a comparatively lucky incident as no one was injured because of this error in calculation. Had it been a British troop marching on the bridge instead, it would have collapsed and caused great casualties. In view of this, it was decided that all troops must make sure their footsteps are not in sync to prevent breaking a bridge.

 In this book, most of the mistakes introduced are caused by people’s carelessness. It is hard to fully stop people from making mistakes. Humans are often bad at learning from mistakes, and it is even harder to predict unknown mistakes that may happen. We can only try our best to avoid mistakes by being prudent. As the book only includes publicly known accidents, one can be sure that there are more unexposed mistakes in reality than we would ever expect. The life lesson from the book is to be careful in every important decision. Don’t let yourself be a part of the statistics.

 I truly recommend this book to others. The book is written in a hilarious way, yet it is also very informative. It uses daily examples that are accessible to readers so that they are able to understand the cases easily. Readers can educate and entertain themselves at the same time. For those who are interested in mathematics, why not give this book a try and learn about how math can influence our life?

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