A company just cracked open an AI model trained on biological data and found a new class of potential Alzheimer's biomarkers hiding inside the weights — something no researcher had written down or gone looking for. Goodfire built the tool that made that possible: a platform that reverse-engineers what neural networks actually learned, down to individual concepts, and lets engineers edit behavior with surgical precision instead of guessing in the dark. The same technique that once taught a grandmaster chess concepts no human had ever articulated is now being pointed at medicine — and the first result came back pointing straight at one of the hardest diseases on earth.