However, the discovery of a frozen human foot in early October has brought a partial end to a century-long search — and reignited one of the greatest mountaineering mysteries of all time.

Even this core isn’t solid; if you were to defy both physics and human biology to make it to the core, setting foot in it would lead to you instantly dissolving into its hot, melty depths.

There’s a technological revolution underway that’s making it faster and easier for scientists to see the molecules that undermine human health — and possibly fight the problem. Scripps ...