• Helium weighs 0.164kg per cubic metre. Graphene sheet weighs only 0.77mg per square metre. If you could make a sphere out of a single layer of graphene, and have a vacuum inside (graphene is allegedly impervious to gas) it would become less dense than helium at sizes above 0.014mm

• Graphene foam can be made up of tiny spheres of graphene that contain a vacuum. The graphene spheres are large enough that the average density of the graphene and vacuum is less than helium
  ................
  Some interesting thoughts spring to mind. For one thing a 'fluid' made of tiny graphene spheres would NOT be compressible. For some purpose it would behave much the same as lighter than air liquid.

Think about THAT for a minute. In lighter than air balloons the envelope EXPANDS as the ballon rises (the barometric pressure decreases)...this causes engineering problems, none of which would apply with a lighter than air liquid.

BUT WAIT...

Not quite the same thing...but pretty close. If the two concepts can be 'melded' together THEN IMAGINE graphene spheres that are filled with nothing are formed into a foam...then it's a solid. Not JUST a solid either...it's
MUCH stronger than steel.

Imagine what could be done with a lighter than air...structural solid?

The mind boggles.

Skyscrapers that are 'tethered' to the ground (or not)...can you say EARTH QUAKE PROOF?
Flood proof too.

Anything proof actually.

at the moment less than 10% of the land surface of the planet is densely inhabited. (drive across WTexas or the Austrailian Outback to see what I mean..NOT many people live there. Even less live on the oceans)...

With this tech...the entire globe would be habitable in a layer (above the surface) several miles deep.
(might want to stay at a higher altitude over the poles and the mountains..)

BONUS

Solar panels work BETTER when it's cold...a couple of miles high
There's more SUNLIGHT..a couple of miles high
above the clouds...