  We have studied solid hydrogen under pressure at low temperatures. With
increasing pressure we observe changes in the sample, going from transparent,
to black, to a reflective metal, the latter studied at a pressure of 495 GPa.
We have measured the reflectance as a function of wavelength in the visible
spectrum finding values as high as 0.90 from the metallic hydrogen. We have fit
the reflectance using a Drude free electron model to determine the plasma
frequency of 30.1 eV at T= 5.5 K, with a corresponding electron carrier density
of 6.7x1023 particles/cm3, consistent with theoretical estimates. The
properties are those of a metal. Solid metallic hydrogen has been produced in
the laboratory.
