For many years it has been thought that hydrogen exists in a metallic form under significant pressure, however it has never been proven. This week a study was published by two German scientists in Nature Materials, a reputable peer-reviewed journal, indicating that they have discovered metallic hydrogen. Excitement has surrounded this material for years because of the plethora of possibilities for real world applications, however skepticism surrounds this discovery.
The experiment was performed by Mikhail Eremets and Ivan Troyan of the Max-Planck Institute for Chemistry in Mainz, Germany. They put 99.95% pure hydrogen into a diamond anvil cell. The device leaves room for a sample between two opposing diamonds and is used for experiments that need to be performed under extreme pressure, ~3,000,000 atmospheres (300 Gigapascals). Pressure, electric, and vibrational measurements were taken at low temperatures to examine the results.
Eremets and Troyan determined that at 220GPa and room temperature hydrogen exhibits electrically conductive activity. Then after lowering the temperature further and increasing the pressure they viewed metallic like behavior from the hydrogen, however the indication was subtle. Eremets and Troyan fully believe this is a sign of metallicity, but many other groups are not convinced by their evidence. Arthur Ruoff, a materials scientist at Cornell University and a leader in the search for metallic hydrogen, believes that there should be a 4000% resistance increase, but only a 20% resistance increase was seen by Eremets and Troyan.
Ruoff is not the only leader in the field with concerns about the bold claim. William Nellis at Harvard University expresses some of the same skepticism as Ruoff. They both think there could be an additional reaction happening with a material in the experimental apparatus.
Despite the controversy swirling around the recent publication, if or when metallic hydrogen is discovered it could lead to real world applications in the area of superconductivity. Perhaps, it is a little too early to get excited about this discovery, but the advancement in this area of materials science is something to be watchful over.
I have always been fascinated with the intersection of science and skepticism. If there is a controversial scientific debate you have always wondered about, please let me know. Perhaps after digging through the scientific literature, I can clear up some curiosities (or I can muck them up). Find me on twitter at jhargis9.