Researchers may have finally succeeded in producing metallic hydrogen, a complex and elusive state that was first theorized over 80 years ago.
This impressive feat was achieved by cooling down hydrogen to 5.5 Kelvin (-268 ° C/-450 ° F) by Dr. Ranga Dias and Professor Isaac Silvera of Harvard University while compressing it to a staggering pressure of 4.8 million atmospheres. This week in Science, the breakthrough is reported.
Using diamond anvil cells, the incredibly high pressure was achieved. But it wasn’t an easy approach. For many years, scientists have been trying to get to this pressure, and although they have nearly got there, it is only now that scientists have the right set-up.
“Because diamonds failed before a sufficiently high pressure was reached, metallic hydrogen was never made before,” Professor Silvera told IFLScience. “We don’t use natural diamonds, we use synthetics that are very homogeneous, whereas natural ones have inhomogeneities and internal defects and impurities.”
Hydrogen is a molecular gas in its standard form with its atoms bound in pairs, each of which shares an electron with the other. The pressure mounts and things get weird when hydrogen is placed between the anvils.
Hydrogen becomes opaque (hence the nickname black hydrogen) at a pressure of 3.2 million atmospheres and is also a semiconductor. However, only much higher pressure can break the molecular bonds and create the phase of metallic hydrogen. The gas seemed to turn into metal, with an atomic metal’s expected properties. The two scientists believe that metallic hydrogen is solid, but the team was not able to confirm it experimentally.
Certainly, confirmation is key. While the team is very confident, others have doubted that the long-awaited phase is what has been seen.
E first predicted this peculiar hydrogen phase in 1935. Wigner as well as H.B. Huntington, and this has since become the “holy grail of physics of high pressure.” But in estimating the necessary pressures, Wigner and Huntington were wrong. They believed that metallic hydrogen could be achieved with a pressure of 250,000 atmospheres, nearly 20 times lower than was claimed
For the sake of science, the ability to create metallic hydrogen would not just be a science triumph. It has a multi-disciplinary impact to understand the metallic properties of the most abundant element in the universe.
After the pressure is removed, metallic hydrogen is considered to be metastable at room temperature, so it could be used in nuclear fusion. It is also thought to be a superconductor of high temperature, which if confirmed would be an incredible breakthrough. Even astronomy could benefit from this discovery–metallic hydrogen could be the core of Jupiter, Saturn, and exoplanets.