rationalskepticism.org

I'd like to know how the authors quoted by the NS article think that metallic hydrogen can continue to exist after the presssure has ben taken off. Perhaps they are thinking of the formation of diamond from graphite at vey high T and P, which certainly does survive the loss of high T and P. However, the difference between graphite and diamond is only in the C-C bonds - ie, the outer, valence electrons - the inner electronic orbitals are essentially unaffected, whereas the difference between gaseous H and metallic H is that the orbitals themselves are being compressed in metallic H, so when this compression is released, the orbitals must return to their normal size.

EDIT: I see that the science article says that metallic H is expected to be metastable when the pressure is released. I'd like to know the potential barrier creating this metastability. I suspect that it would be low, making it very like instability.