World Models

🎧 Prefer to listen? Your browser does not support the audio element. Two weeks ago, Anthropic published a paper that should change how you think about your AI tools, and almost nobody outside research circles understood what it actually said. We covered Claude’s “inner life” and OpenAI’s super app when the news broke, and before that, how Sonnet 5 made agents affordable for solo builders. But the J-Space discovery deserves a closer look, because its implications go well past academic curiosity. ...

🎧 Prefer to listen? Your browser does not support the audio element. Anthropic’s interpretability team used a technique called the “Jacobian lens” to identify a zone inside Claude’s neural network where abstract concepts — things like “the user wants a comparison” or “this fact needs verification” — float around during processing. These concepts shape Claude’s answer but never appear in the output. A 2025 MIT Technology Review interview with senior editor Will Douglas Heaven, who holds a PhD in computer science, pushed back on Anthropic’s framing of this discovery: “I don’t love using those kinds of terms. LLMs are not brains.” ...