We usually decide that problems are hard because smart people have worked on them unsuccessfully for a long time. It’s easy to think that this is true about AI. However, the past five years of progress have shown that the earliest and simplest ideas about AI — neural networks — were right all along, and we needed modern hardware to get them working.Historically, AI breakthroughs have consistently happened with models that take between 7–10 days to train. This means that hardware defines the surf...