Water Not So “Squishy” Under Pressure

The Z Accelerator at Sandia National Laboratories. Thicknesses of the aluminum and quartz drive plates and water samples were a few hundred microns; the rear quartz window was a few millimeters thick.

When squeezed to pressures and temperatures like those inside giant planets, water molecules are less squeezable than anticipated, defying a set of decades-old equations used to describe watery behavior over a range of conditions.

Studying how molecules behave in such environments will help scientists better understand the formation and composition of ice giants like Uranus and Neptune, as well as those being spotted in swarms by planet hunters. The new work, which appears in the March 2 Physical Review Letters, also suggests that textbooks about planetary interiors and magnetic fields may need reworking.

In the lab, scientists generated pressures reaching 700 gigapascals—almost 7 million times the atmospheric pressure at the Earth’s surface—using the Z machine, an accelerator at Sandia National Laboratories in Albuquerque, N.M. “It really is a regime that we don’t experience in our lives,” says planetary scientist Jonathan Fortney of the University of California, Santa Cruz. “Even at the bottom of the ocean.”

Scientists from Sandia, Harvard University, the University of Rostock (Germany), and the University of California-Santa Cruz collaborated on this research.

Read the rest of the article at Science News.

Read the abstract at Physical Review Letters.