The simplest element can withstand titanic pressures

Squeezed between two diamonds hydrogen refuses to change

For years scientists have believed that if you take hydrogen, the simplest atom, and squeeze it hard enough it will become a kind of metal. However it seems scientists will have to think again, as our science correspondent David Whitehouse reports.

A team of scientists at Cornell University have tried to create metallic hydrogen by squeezing it between two diamonds applying pressures close to that found at the centre of the Earth. But the hydrogen would not change.

Even under a pressure of 50 million pounds per square inch, over four million times greater than normal atmospheric pressure, hydrogen refuses to become a metal.

"It is a very hard problem," says professor Arthur Ruoff. "Hydrogen is the simplest atom, but it's not at all the simplest solid."

Hydrogen is the most abundant element in the cosmos. It consists of an electron circling a proton. Scientists understand it quite well when it is a gas but clearly not very well when it is under pressure.

Recent calculations suggest that a pressure of over 100 million pounds per square inch will be needed to make hydrogen into a metal.

Scientists are interested in hydrogen metal because they hope that it will be metastable remaining metallic after the pressure has been taken away.

It could have the ability to "superconduct" electricity, a property that would revolutionise power generation and distribution.