What was once theory is now reality after a pair of scientists successfully turned hydrogen into metal, 80 years after it was first suggested. For fuels, superconductors and more materials, this is a turning point.
“This is the holy grail of high-pressure physics.”
This is quite a suitable claim, made by Isaac Silvera, one of two scientists behind a world-first: the creation of atomic metallic hydrogen.
About 80 years after it was first theorised, this new form of hydrogen could dramatically revolutionise rocket fuel, become a room-temperature superconductor and possibly lead to the creation of even more mystery materials.
Put them under pressure
“It’s the first ever sample of metallic hydrogen on Earth, so when you’re looking at it, you’re looking at something that’s never existed before,” said Silvera, Thomas D Cabot professor of the natural sciences.
He, along with postdoctoral fellow Ranga Dias’s paper, published in the journal Science, could well go down as two of the most influential physicists of their time.
Everything from super-fast computers, ultra-efficient vehicles, electricity breakthroughs and high-speed magnetically levitating trains are now possible, according to the duo.
The researchers put huge force on a small amount of hydrogen, greater than the pressure at the centre of the Earth, which broke down the molecules of the gas, transforming them into atomic hydrogen, which is a metal. They basically squeezed a gas into a solid.
The next step is to investigate whether or not the removal of the pressure, after the atomic metallic hydrogen has been created, sees it return to a gaseous state. If it stays solid, like how diamonds do after the pressure and heat on graphite is removed, then we’re onto an even bigger winner than we thought.
“That would be revolutionary,” said Silvera. “As much as 15pc of energy is lost to dissipation during transmission, so if you could make wires from this material and use them in the electrical grid, it could change that story.”
Its role as a superconductor is one of the appealing elements, with research into this field so far finding room-temperature examples incredibly elusive. Graphene has consistently been lauded as the answer to most physicists’ problems, though this could prove even better.
Elsewhere, the potential for a new fuel source is also something that has the science community abuzz. Rocket fuel of this kind could make space travel previously assumed impossible, possible.
“It takes a tremendous amount of energy to make metallic hydrogen,” Silvera explained. “And if you convert it back to molecular hydrogen, all that energy is released, so it would make it the most powerful rocket propellant known to man, and could revolutionise rocketry.”
The most powerful fuels in use today are characterised by a ‘specific impulse’ – a measure of how fast a propellant is fired from the back of a rocket – of 450 seconds. The specific impulse for metallic hydrogen, by comparison, is theorised to be 1,700 seconds.
This would allow for greater exploration of our solar system, with rockets needing one stage of fuel to get into orbit, all the while carrying larger loads.
“It’s a tremendous achievement, and even if it only exists in this diamond anvil cell at high pressure, it’s a very fundamental and transformative discovery,” said Silvera.
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