Diamond, the hardest material in the word, has been squeezed with the world's largest laser to help understand what happens to matter exposed to the enormous pressures in the centers of stars and gas giant planets.

A tiny fragment of diamond was crushed down to pressures similar to pressures existing in the core of the planet Saturn, some 14 times the pressure found at the center of our Earth.

The experiment at the United States National Ignition Facility was designed to yield insights into the conditions existing deep in the centers of huge, carbon-rich planets, the researchers report in the journal Nature.

Carbon is one of the most common and abundant elements throughout the universe.

"We don't know what lies within the core of Jupiter or Saturn but now for the first time we now have the ability to study how matter exists under these extreme conditions of pressure and temperature," says study lead author Ray Smith, of the Lawrence Livermore National Laboratory in California where the ignition facility is located.

Those conditions are predicted to result in dramatic alterations to the properties of matter, the researchers say, suggesting diamonds might be lurking in the central cores of giant planets.

Smith and research colleagues used 176 laser beams to subject a diamond to as much as 50 million atmospheres of pressure, and found that diamonds can withstand pressured of that level.

"The initial goal, which we achieved, is to generate conditions that are relative to planetary cores," says Smith. "The expectation is that we will get these really weird states of matter."

In the diamond experiment no exotic forms of matter were observed, the researchers said.

"That doesn't mean it didn't take place," says Smith. "It just means we weren't able to measure it."

The researchers say they hope ongoing experiments of a similar nature might create exotic kinds of matter that would persist after the massive pressures were removed, allowing such matter to be studied for clues to what is happening in the cores of giant gas planets both in the solar system and in the universe beyond.

The National Ignition Facility was created to conduct experiments in nuclear fusion, but its capability of creating extremely high pressures has made it useful for other forms of research.

"Although the pressures probed in the current experiments are immense, nature is even more ambitious," researchers wrote in an article accompanying the study published in Nature. "The giant exoplanets are a stepping stone to stars where [even greater pressures] are reached."