from wikipedia.com

For a few years now, there have been articles here and there about this substance that looks like solid smoke, something from Wonderland or Neverland.  Are your eyes playing tricks on you?  Is it an Onion piece? No, this is an actual substance that has been created by people vastly smarter than me.

Here is a succinct description from Wikipedia:

Aerogel is a synthetic porous ultralight material derived from a gel, in which theliquid component of the gel has been replaced with a gas. The result is a solid with extremely low density^[1] and low thermal conductivity. Nicknames include “frozen smoke”,^[2] “solid smoke”, “solid air” or “blue smoke” owing to its translucent nature and the way lightscatters in the material. It feels like fragile expanded polystyrene(Styrofoam) to the touch.

Aerogel was first created by Samuel Stephens Kistler in 1931, as a result of a bet with Charles Learned over who could replace the liquid in “jellies” with gas without causing shrinkage.^[3][4]

Aerogels are produced by extracting the liquid component of a gel throughsupercritical drying. This allows the liquid to be slowly dried off without causing the solid matrix in the gel to collapse fromcapillary action, as would happen with conventional evaporation. The first aerogels were produced from silica gels. Kistler’s later work involved aerogels based on alumina, chromia and tin dioxide. Carbon aerogels were first developed in the late 1980s.^[5]

What is it used for? Here are some examples:

http://www.aerogel.com/products-and-solutions/cryogel-z/ shows how aerogel is used for insulation.

Cryogel® Z

FLEXIBLE CRYOGENIC INSULATION FOR COLD WORK

Cryogel® Z cryogenic insulation is used in below-ambient-temperature applications in the oil and gas processing industry (LNG, LPG, ethylene, etc.) and industrial appliances. Cryogel® Z has the lowest k-value of any widely used cryogenic insulation material, reducing thicknesses by 50%-80%. Cryogel® Z’s flexible blanket form, with a factory-applied vapor barrier, is both fast to install and durable, resulting in lower-cost, higher performing designs.

Other uses:

Aerogels are used for a variety of applications:

• In granular form to add insulation to skylights. Georgia Institute of Technology’s 2007 Solar Decathlon House project used an aerogel as an insulator in the semi-transparent roof.^[19]
• A chemical adsorber for cleaning up spills.
• A catalyst or a catalyst carrier.
• Thickening agents in some paints and cosmetics.
• Laser targets for the National Ignition Facility.