untitled by Millie J.A Clinton on Flickr.

E. Dauber by James Fitzgerald III on Flickr.

Frozen smoke! Well, not quite. Aerogel, whose nickname, above, references the way the substance looks, is a synthetic, ultralight material. It may look airy, but it feels like styrofoam to the touch, and just 2 grams can support a 2.5 kg brick.