This picture is of a 2.5kg brick supported by a piece of aerogel, the worlds lightest solid material. This particular piece weighs in with a mass of 2 grams.
Aerogel is nicknamed 'frozen smoke' or 'solid air', due to the fact that it is composed of 99.98% air by volume. Aerogels are a diverse class of amazing materials with properties unlike anything else known. They exhibit the lowest thermal conductivity of any known solid, and are the lowest density structural materials ever developed.
In spite of their name, aerogels are solids and not gels. The name is derived from the production process, the liquid component of a gel is extracted through supercritical drying. The first aerogels were produced from silica gels, but later work produced aerogels based on alumina, chromia and tin dioxide.
