The lightest solid is silica aerogels, made of tiny spheres of bonded silicon and oxygen atoms linked together into long strands separated with air pockets. They appear almost like frozen wisps of smoke. They also have the lowest conductivity, lowest solid density, highest porosity, highest surface area, and the highest dielectric constant, giving them the potential of being used in many applications. Understandably, their use is not currently widespread due to the expense to create them, and the difficulty in insulating capabilities will allow their use in place of fiberglass and polyurethane foam, significantly reducing global energy consumption and greenhouse gas emissions.