When not being used to study nuclear fusion, the world’s largest laser can be found crushing diamonds, to study planetary formation, of course.
Well, that’s a little bit misleading. The world’s largest laser and 175 other lasers combined to exert 50 million times the amount of earth’s atmospheric pressure on a single diamond, to be exact.
The laser, which is housed at the US National Ignition Factory at the Lawrence Livermore National Laboratory, measures more than 30 feet long and can be focused on a millimeter target. In doing this, the researchers, led by Lawrence Livermore’s Ray Smith, were able to complete a process known as “dynamic ramped compression.” That means they were able to slowly and evenly compress the diamond in such a way as to not liquify it and instead compressed it to the density of lead. Smith published his findings in Nature.
If you’ve seen it before, it’s because it was a stand-in for the starship Enterprise’s warp core in Star Trek Into Darkness. It’s got a lot of uses, to say the least.
So, why do this? To find out what the cores of massive planets like Saturn might look like. As the name suggests, gas giants are made out of gas, but some scientists believe that the core of Jupiter, Saturn, and other, even larger exoplanets might be solid. There are plenty of theoretical ways to calculate a planet’s density and what might be at its core, but there are very few ways to study what happens when elements are subjected to the insane pressures of huge planets.
That’s exactly what Smith did, exerting five terapascals of pressure on the diamond (that’s equal to 14 times the pressure at Earth’s core, and roughly equal to the expected pressure at Saturn’s core).
“The discovery of multiple planets beyond our Solar System, many of which are much larger than Jupiter and Saturn, has left to a dramatic change in our picture of the Universe,” Chris Pickard of the University of London, wrote in an accompanying Nature article. “Understanding the make-up and evolution of these exoplanets requires the development of theoretical models, which depend on the pressure-density equations of state of the most likely planetary materials. Until now, these equations of state have been largely determined by extrapolating from terrestrial data.”
Smith’s findings suggest that, more or less, those theories are on point. Next up? Simulating the pressure of stars, which is an entirely different proposition.
“The giant exoplanets are a stepping stone to the stars, where petapascal pressures are reached,” Pickard wrote. So, take a terapascal and add at least three zeros. That’s a lot of pressure.
*Also see https://www.llnl.gov/