Harvard University physicists were thrilled last year when they successfully transformed hydrogen into a metal state. Scientists predicted the phase change in 1935, but no one had yet to create it in a lab setting. The Harvard team not only created the metallic hydrogen sample but they maintained its stability in the lab. However, the team reports they've lost the sample. They're not entirely sure how it happened, either.
[Image Source: Harvard via Youtube]
Metallic hydrogen can fluctuate between a gas and solid metal state depending on pressure and temperatures. To maintain the metallic state, researchers held the sample between two diamonds at temperatures near absolute zero.
The researchers were about to ship the entire sample and system to the Argonne National Laboratory. The diamond vice failed during laser testing to measure the system's pressure. The laser destroyed one diamond, and the team doesn't know why. They have yet to find the sample. This doesn't necessarily mean the sample is gone forever, team leader Isaac Silvera said.
"Basically, it's disappeared," he said in an interview with ScienceAlert. "It's either someplace at room pressure, very small, or it just turned back into a gas. We don't know."
They created the stable sample in October last year. However, Silvera's team wanted to verify its existence before publishing the findings. The news became public last month in the journal Nature.
The sample itself was extremely small - only 1.5 micrometers thick and 10 micrometers in diameter. That's smaller than the human hair. There's a (small) chance the sample is simply on the floor of the lab and cannot be seen.
In a statement made shortly after releasing their findings in January, Silvera even said:
"One prediction that's very important is metallic hydrogen is predicted to be meta-stable. That means if you take the pressure off, it will stay metallic, similar to the way diamonds form from graphite under intense heat and pressure, but remains a diamond when that pressure and heat is removed."
The larger possibility, however, is that after being exposed to room temperature and lacking the vice's pressure, the metallic hydrogen reverted back to one of its standard properties.
Silvera, who spent over 45 years of his career working toward this goal, admits disappointment - but not defeat.
"We're preparing a new experiment to see if we can reproduce the pressures we achieved the first time, and reproduce our metallic hydrogen," he said.
The methodology behind the metallic hydrogen was first proposed by Eugene Wigner and Hillard Bell Huntingdon over 80 years ago. They theorized that under immense pressure, the lattice would allow electrons to flow from one hydrogen molecule to another. While the theory ultimately worked, their estimations did not. Wigner and Huntingdon proposed 25 gigapascals (GPa) could create solid metallic hydrogen. That was a far cry from the 495 GPa ultimately used.
Why does it matter?
There's a reason Harvard and the rest of the scientific community are scrambling to recreate metallic hydrogen. The properties theorized regarding it make it one of the most valuable creations in recent years. It could be the world's greatest superconductor, carrying current with almost no resistance.
Post-doctoral fellow Ranga Dias, who worked with Silvera on the project, also noted that it could be "the most powerful rocket propellant known to man, and could revolutionize rocketry."
To watch the researcher discuss the development of the initial project, watch the video below: