Aerogel. The holy grail of building materials. Samples are lusted after in materials classes everywhere. (available now on eBay, natch.) Insulator, structure, window, fabric, comet-catcher, aerogel can potentially revolutionize the building industry. It could revolutionize every industry….if only it wasn’t so damn expensive. Wired gives a brief history of the material that’s made of 99% air.