Comment Re:So, is it a solid, or a construction. (Score 2, Interesting) 556
I believe that the density is measured by the volume of the cube divided by the mass of the cube. (In many cases it's also motioned that 98.8% of an aerogel is empty space.) But keep in mind that the truly remarkable feature about this is the scale at which this occurs.
The framework that makes up an aerogel is so fine that the individual components are around 3-5 nanometers in thickness. (An atom is about 0.1nm).
In your aluminum example the average density of the space defined by the cube would be less dense. But the foil that makes up its walls is easily discernable from the air. It might be easier to think of an aerogel like a sponge, or angel food cake where there are tunnels of air (or empty space if you'd rather) in the material. But in the case of the aeogel the tunnel are microscopically small complex in shape.
The framework that makes up an aerogel is so fine that the individual components are around 3-5 nanometers in thickness. (An atom is about 0.1nm).
In your aluminum example the average density of the space defined by the cube would be less dense. But the foil that makes up its walls is easily discernable from the air. It might be easier to think of an aerogel like a sponge, or angel food cake where there are tunnels of air (or empty space if you'd rather) in the material. But in the case of the aeogel the tunnel are microscopically small complex in shape.
