Y2K was the nerdy disaster that wasn’t. The fear was that the moment 1/1/00 rolled around, some computers would think it was Jan. 1, 1900. What could go wrong? Maybe highly computerized hydroelectric dams would open their floodgates! Or maybe all date math trying to subtract from 00 would end up negative, and suddenly your mortgage would have been paid off dozens of decades ago!
The world freaked out. Software engineers stayed up late. In the end, Y2K had some terrible real-life consequences, but it also didn’t turn out to be a complete catastrophe that required stockpiling ammunition and MREs. After airplanes didn’t fall out of the sky, everyone breathed a sigh of relief. The problem, as the public learned so well in the run-up to the New Year, was that for decades, software engineers had left out the century to save on space when storing dates. It was as though they had assumed their software would always run in a year that began with 19. For many who were still just getting used to dial-up internet, Y2K was their first exposure to the potential fragility of software.