Physicists with the U.S. Department of Energy have discovered a new phase of matter—and, with apologies to George R. R.

Solid, liquid and gas are the three main states of matter. When a substance changes state, this is a physical change because no new substances are produced and the change is reversible.

The physical properties of seawater include ... Density in particular is an important property in ocean science because small spatial changes in density result in spatial variations in pressure ...