The crowd at that night’s GPT-4 hackathon was so large as to render the Wi-Fi basically nonfunctional. Every room overflowed with hackers crowding around whiteboards. In the kitchen, Chinese takeout was laid out on a table. A smattering of investors were present to check out the demos, which started at 8 p.m. with short speeches from the organizers. The speeches were all variations on a theme: We are living in a momentous time. Maybe in a few decades from now, we’ll look back at all these seminal A.I. achievements and see that they all came from this house in Hillsborough....