Northwestern University chemist Thomas J. Meade means no disrespect to his medical colleagues, but when he looks at the state of the art in diagnostics, he suggests that, for some procedures, physicians might as well use "stone knives." Take, for example, mammography. "You know going in that there's a one in five chance of a false positive or a false negative. You have an x-ray that's not even smart enough to differentiate a shadow cast by a calcium spot from a tumor. After reading the film and seeing a shadow, they do the prudent thing and stick a 16-gauge needle in you for a biopsy. Then you have to spend the next five days freaking out that you've got breast cancer until you get the results," he says.

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