A New Form of Water: Melting ice turns oddly dense

It’s common knowledge that liquid water expands when it forms ice. Conversely, frozen water compacts as it melts. Now, a team of European researchers has made an ultrathin film of supercooled water that’s much denser than normal water.

The experimenters suspect that they have created the first sample of a previously hypothesized form—or phase—of water known as high-density liquid water, or HDL.