The Fascinating Science of Heavy Water

In one science-fiction novel, people shrink Earth’s water supply to melt Antarctica’s ice caps — by turning water into a plastic substance they can later dissolve back into liquid.

Fairy tales are lies that carry a grain of truth, and dissolving water in water sounds fantastical — until you see something similar in real life.

It seemed like our understanding of water was complete. But scientists discovered a form of water that contains an isotope of hydrogen called deuterium, known as heavy water. It exists in relatively small quantities — about one part for every 6,250 parts of regular tap water. In other words, heavy water makes up just 0.02 percent of the weight of each drop. Collected from around the globe, heavy water could fill a body of water the size of the Black Sea!

One striking property is how readily it mixes with ordinary water: heavy water dissolves into regular water very easily.

It’s still unclear how humans might harness this characteristic. But over time, it could prove to be useful.