The name of N. Ashcroft many students link with his famous book, but in fact, his great contribution to science is his work on metallic hydrogen.

At the very earlier stage of his carrier, N. Aschroft made his maybe the most remarkable discovery: the simplest metal - hydrogen should be high temperature superconductivity because this good metal has high frequencies of the lattice oscillations which strongly interact with electrons. Metallic hydrogen requires very high pressures and gradually he became the main figure in the theory of dense solid physics. He introduced the highest level of physics into the high pressure field and fueled it with many ideas. He showed that the quantum nature of hydrogen leads to unusual phenomena. In particular, the melting curve of hydrogen should turn down at high pressures. This can lead to a superfluid state at low temperatures and in combination with the superconductivity to a new state of the matter.

Metallic hydrogen is a high-value target goal for many researchers and it enormously stimulates the development of high pressure field towards multimegabar pressures. Neil Ashcroft was deeply interested and knew experiment and the high pressure field as a whole. He was the best reviewer at the Gordon conferences as we vividly remember his bright presentation at GRC in 2006. He often put technical questions to experimentalists. It seems he wanted to realize how the experiment is reliable to be a basis for the theory.

The high-pressure experiment is regrettably slow and could not fit his pace. I think, he was tired to wait until the superconducting hydrogen will be realized and came with a remarkable idea that hydrogen dominant materials can substitute or even be better than pure hydrogen in terms of high temperature superconductivity. In contrast to pure hydrogen, lower, realistic pressures are required for the metallization. He made this suggestion at the right time. Soon methods of prediction of structures appeared which supported his general theoretical suggestions. The experiment also was developed for the synthesis and study of hydrogen dominant compounds. This triad of general theory, simulations and experiment produced remarkable results. The critical temperature of conventional BCS superconductivity skyrocketed. Now the high pressure community is well recognized for making SCs near room temperature and likely above. On basis of the high pressure studies likely new high temperature superconductors will be made at ambient pressures. Fortunately, at least this theory was fulfilled during his life. His even more exciting predictions such as superconductivity, superfluidity in pure hydrogen or deuterium are ahead and they will drive the high pressure field for many years. The name of N. Ashcroft will stay in the high pressure science.