As AI gets stronger, how much knowledge still belongs in your own head? This AI on Air clip is excerpted from a recent episode on the @ycombinator show, featuring Patrick Collison @patrickc, co-founder of @stripe, on what college students should still learn and derive from first principles. ▷ His mental model is cache: Jeff Dean's famous numbers every programmer should know are a reminder that L1 cache, RAM, and the network differ radically in bandwidth and latency; knowledge works similarly, because asking an agent to compute or look something up is far slower than retrieving it from cognitive L1 cache. ▷ Even granting the models their full capabilities, neuronal lookups should stay much faster for a long time, since the brain allows far more round trips than muttering to a voice interface, whispering, or typing out a query. ▷ Revealed preference points the same way: companies like Stripe and the labs still place an enormous premium on cognitive ability, so renouncing that training before evidence shows those benefits are saturated would be premature.