"In a back room of New Scientist's offices in London, I sit down at a table with the Russian biochemist Mikhail Shchepinov. In front of us are two teaspoons and a brown glass bottle. Shchepinov opens the bottle, pours out a teaspoon of clear liquid and drinks it down. He smiles. It's my turn.
I put a spoonful of the liquid in my mouth and swallow. It tastes slightly sweet, which is a surprise. I was expecting it to be exactly like water since that, in fact, is what it is - heavy water to be precise, chemical formula D2O. The D stands for deuterium, an isotope of hydrogen with an atomic mass of 2 instead of 1. Deuterium is what puts the heavy in heavy water. An ice cube made out of it would sink in normal water."