All models are wrong − a computational modeling expert explains how engineers make them useful

When engineers design things, they use models to predict how the things will work in the natural world. But all models have limitations. MTStock Studio/E+ via Getty Images

Nicknamed “Galloping Gertie” for its tendency to bend and undulate, the Tacoma Narrows Bridge had just opened to traffic on July 1, 1940. In a now infamous failure, in the face of moderate winds the morning of Nov. 7, 1940, the bridge started to repeatedly twist. After an hour of twisting, the bridge collapsed. One fatal engineering assumption led the bridge to shake itself apart.

At the time, many designers believed that wind could not cause bridges to move up and down. That may seem like an obvious fact now, but that incorrect assumption cost about US$65 million in today’s dollars and a dog’s life.