Two scientists reported that their attempt to make metallic hydrogen was successful. This form of hydrogen has been regarded as really hard to obtain for about 80 years, and this explains why other scientists are still skeptical.
Hydrogen is the first element on the period table. It is also the simplest element and it makes up about three quarters of the mass of the universe if you take out the dark matter. Usually, hydrogen is a gas but, if cooled at -253 degrees Celsius, it turns liquid. Liquid hydrogen is a common rocket fuel that is widely used.
We already saw how useful gaseous and liquid hydrogen are. However, metallic hydrogen can prove even more useful. Some scientists think that it may conduct electricity at room temperature with no resistance. This would make it a high temperature superconductor and the distribution of electricity more efficient.
This is extremely convenient, since most superconductors work only if cooled nearly to absolute zero. Even the highest temperature superconductor we know only works at -70 degrees Celsius.
Many scientists tried to look for metallic hydrogen over time and they were not successful. For quite a long time, they believed its existence is not possible. However, they found out that they may obtain metallic hydrogen at a pressure 250,000 greater that the pressure on Earth. Since then, scientists tried all pressure methods to try to squeeze the gas into a metal. They even built presses with diamond tips. All attempts proved unsuccessful.
This might have changed, though. Isaac Silvera and Ranga Dias, physicists at Harvard, reported that they have succeeded in obtaining metallic hydrogen at a temperature of -268 degrees Celsius and a pressure of 495 gigapascals. This is about 5 million times stronger that the pressure we feel at Earth’s surface.
They noticed that a vital failure in the previous attempts was the fact that diamonds cracked, so they found a way to polish them so that they wouldn’t crack. Then they put the diamond inside a cryostat (a cooling tool) and squeezed the gas with a screw.
The hydrogen turned black at 335 gigapascals, thus turning to a state that absorbed light. At 495 gigapascals, hydrogen turned shiny. This was the moment when they noticed it had turned metallic.
This is quite big, if they actually succeeded in obtaining metallic hydrogen. It would be the first sample ever that is present on Earth, so those looking at it are witnessing something that has never existed before.