Any materials scientist will tell you that hydrogen is a tough nut to crack. Although the simplest of the atoms, hydrogen in its molecular state is incredibly complex. The long-sought goal of turning the element into a metal, it has been predicted, would require pressure close to that found at the center of the Earth. Researchers at Cornell University (Ithaca, NY) have dispelled that theory: They submitted hydrogen gas to just such pressure, but the element remained unchanged. "It seems," says Cornell's Arthur Ruoff, "that the pressure required for this transition is even higher than previously thought." The researchers found that solid hydrogen showed no signs of looking like a metal at pressures of up to 342 GPa. The pressure at the center of the Earth is about 361 GPa--more than four million times surface pressure. Such incredible pressure was achieved at Cornell by compressing the hydrogen in a diamond anvil cell, a small device consisting of pairs of the highest quality diamonds with tips beveled to one-fourth the diameter of a human hair. The diamonds, 15 in all, ultimately cracked. E-mail firstname.lastname@example.org.