Feel the dielectric force

The dielectric constant of water confined in nanoscale channels is far below that of bulk water Water is the foundational element of life. Its high melting and boiling temperatures relative to analogs such as hydrogen sulfide are a precondition to life. The density maximum at 4°C makes ice float, ensuring that lakes and oceans do not freeze on the bottom. The high surface tension of water enables insects to walk on its surface. Its high dielectric constant makes it an excellent solvent, a key property for many geochemical, biological, and technological processes. These properties can be traced to the strong hydrogen bonding in liquid water ( 1 – 3 ). On page 1339 of this issue, Fumagalli et al. ( 4 ) report on another property of liquid water that relates to its hydrogen bonding: the dielectric constant in thin water layers.