From the hubra, discussion of the invention of the Chinese material with a density, less air density:

TheShock :
In the foam, the pores are closed, and this material is more like a sponge.
If a sponge is thrown into the water, it will also first swim, and then wet and drown.
That is, in the case of sabre material it would be impregnated with vacuum, but now it was thrown into the air and so it drowns?

by agentx001:
by Fuck. Archimedes would have stolen :)