Never Trust a Simulation without a Simple Back-of-the-Envelope Calculation that Explains It

Simulations are a crucial tool for systems engineers, and I have coded, developed, analyzed, tested, debugged and debunked many such simulations. However, they cannot be trusted. All too often system engineers come a cropper due to believing the results of simulations without making sure that the results are correct and relevant. Significant errors can occur for many reasons: bugs, bugs, bugs, incorrect parameters, incorrect physical models, incorrect application of perfectly fine code, incorrect interpretation of accurate results, etc. I was deeply shaped by a system engineering culture that valued simple back-of-the-envelope calculations to provide insight into what was going on. Moreover, I am appalled when I see system engineers blindly believe the results of simulations. My talk will give five or ten examples of system engineering blunders caused by faulty simulations or erroneous physical experiments, as well as two surprising twists.