Clark fired the Z machine at water-infused glass and found melt may grow easier to compress under deep pressure, offering a clue to how early Earth kept its water
Synopsis
Mineral physicist Alisha Clark used the Z machine at Sandia National Laboratories to send shockwaves through water-infused glass samples, recreating pressures near Earth's core during its formation; earlier experiments showed the wet glass became easier to compress as pressure rose, leading her to propose that molten rock could have locked water inside Earth during its magma-ocean phase rather than losing it all or receiving it later from comets and asteroids.
Interpretation
Clark proposes that early Earth may have held onto water internally like a sponge, contrary to the long-standing view that water in a molten early Earth would have steamed off or been blasted into space, with today's surface water delivered later by icy comets and asteroids and interior water carried down by subducting tectonic plates. This alternative is not凭空: it is inspired by geophysical and geochemical discoveries over the past decade or so pointing to a larger interior water reservoir than plate tectonics alone could deliver; the story cites a 2014 analysis of a diamond from deep in Earth's mantle whose mineral impurity contained a surprising amount of water dissolved in its crystal structure. The story presents this as an ongoing debate and explicitly frames Clark's work as one idea from a pool of possibilities, not a settled conclusion.
To test the idea, Clark used the Z machine to send a shockwave through water-infused glass samples, briefly recreating conditions near Earth's centre, using glass as a proxy for melted silicate rock to test how water affects its compressibility. In experiments she had run previously, glass infused with a lot of water seemed to become stiffer, but as pressure increased it became easier to compress; she describes it as 'more squishy the more you squish it, which is not normal behaviour', suggesting melted rock may be good at trapping water under mantle pressures. The evidence comes from shock experiments on the Z machine; the story says this was the final shot of a multi-year project, with each shot taking a full day to set up and costing around US$250,000, involving more than a hundred people.
The story places the work within the long-running debate over the origin of Earth's water: if molten rock can indeed retain water during the magma-ocean phase, much of today's surface water may have been released from the hot interior through volcanoes over geological time, and even greater volumes — oceans' worth — might remain inside the planet. It offers an experimentally testable physical mechanism for the 'interior reservoir' hypothesis, rather than relying only on geochemical inference. The story does not report the final result of that last shot, only that it was the final firing of a multi-year project, so the conclusion remains a hypothesis to be tested.
Perspective
This work speaks to researchers studying planetary interiors and Earth's deep water cycle, in a setting where glass stands in for molten silicate rock and shockwaves briefly recreate pressures near Earth's core. The question it addresses is whether molten rock could retain water during the early magma-ocean phase. For a general reader, it offers a testable mechanism rather than a settled answer about where Earth's water came from.
The story does not report the outcome of the final shot, nor specific pressure values, sample water contents or quantitative conclusions, so 'molten rock traps water' remains a hypothesis to be tested. The 2014 diamond analysis appears only as background and is not detailed. Readers wanting quantitative evidence will need to wait for a follow-up paper or fuller data.