Stamping hydrogen into metal In 1935, Wigner and Huntington predicted that molecular hydrogen would become an atomic metal at a pressure of 25 GPa. Eighty years and more than 400 GPa later, Dias and Silvera have finally produced metallic hydrogen at low temperature. The metallization occurred between 465 and nearly 500 GPa at 5.5 K. Spectroscopic measurements verified that hydrogen was in the atomic state. The observation completes an unexpectedly long quest to find the metallic hydrogen that Wigner and Huntington predicted so long ago. Science , this issue p. 715