Can solid carbon materials be lighter than water and air?

The number of possible hollow carbon molecules with a spatially closed structure is theoretically unlimited. Only a few have been studied up to now, mainly with relative small radiuses. If the structure is big enough, spatially closed, hollow, spherical, and with a monolayer shell, it will have a considerable elevating force when immersed in liquids or gases. Calculations demonstrate that it can be lighter than liquids and air when the molecule is over a certain size. Hollow multilayered carbon structures with such radiuses have already been reported. Development of new methods for synthesis of closed carbon molecules where the shell is reduced to a single layer will allow designing new materials, which are lighter than gases.