This new material is 0.16 kg/m3, presumably if it's filled with vacuum.. Helium is 0.17 kg/m3 at 20°C and hydrogen is 0.09 kg/m3. At the same time, air is 1.2 k

This new material is 0.16 kg/m3, presumably if it's filled with vacuum.. Helium is 0.17 kg/m3 at 20°C and hydrogen is 0.09 kg/m3. At the same time, air is 1.2 kg/m3. So, the volume of each needed to lift 80kg (which would have to include the person and whatever structure to contain the material), is 80/(1.2 - density of material) m3. So: Helium: 78 m3, or sphere of diameter 5.3 m Graphene aerogel: 77 m3, or sphere of diameter 5.3 m Hydrogen: 72 m3, or sphere of diameter 5.1 m