BBC_Knowledge_Asia_Edition_-_May_2016_

around the world have been clamouring to

create it for decades.

STRANGE STUFF

Gas giants do not have a solid surface and are mainly

made up of hydrogen and, to a lesser deg ree, helium

(see ‘Anatomy of a gas giant’, right). On Earth, we

think of hydrogen as a colourless gas. But when it is

subjected to the intense pressures present inside gas

giants, it becomes a f luid. And at even higher

pressures, near the planet’s core, this f luid becomes

‘metallic’ and is able to conduct electricity. Or that’s

what’s thought to happen.

“Our field is extremely contentious,” says Prof

Eugene Gregor yanz at the Universit y of Edinburgh,

whose team became the first to create hydrogen’s

metallic form earlier this year. “There have been

many, many claims of having produced the metallic

for m before.” But, he says, these claims were later

disproved. It means that he’s now being cautious

about his achievement.

“Although we do think that this phase of hydrogen

we have reached is conducting, we don’t have a

bulletproof case. So we are saying this is the

precursor to the metallic phase,” says Gregoryanz.

It’s not only the fact that hydrogen makes up the bulk

of gas giants that makes its metallic phase such a focal

point for research. “It’s also because of the utterly

bizarre and unseen anywhere properties hydrogen is

theor ised to have at high pressure,” he adds. A mong

which, is that the f luid for m of hydrogen is

superconducting – capable of conducting electricity

with zero resistance. “I’m pretty sure that if you show

that the liquid state of hydrogen is superconducting

ABOVE: Hydrogen seas swirl

beneath a turbulent sky in this

artist’s impression of

Jupiter’s surface

PHOTO: SCIENCE PHOTO LIBRARY

SCIENCE