In ice, each molecule grabs the feet and hands of its four nearest neighbors. The placement of these neighbors forms a tetrahedron, or three-sided pyramid. When ice melts, the big question is what happens to this shape. The traditional picture, the one that Saykally is defending, is that water continues to look – for the most part – like ice with four hydrogen bonds around each molecule. The difference in the liquid form is that, at a given time, approximately 10 percent of the hydrogen bonds are broken. Nilsson’s group, in contrast, claims that water takes on a new structure,...