I was considering a buckyball floating in a vacuum.
It's surface is a strongly conducting surface and so I would expect some kind of Casimir effect to apply, i.e. the wavelength of virtual photons inside the buckyball must integrally divide the diameter of it (in order for the waves to vanish at the interior of the surface)
This would suggest that the interior of the buckyball has slightly less energy density than the vacuum itself.
Continuing with this line of reasoning the total energy contained the region of space including and enclosed by the buckyball should be slightly less than the buckyball itself. I.E. there should be a constant $\rho$ equal to the difference between the average energy density of the electrodynamic vacuum versus that inside of the buckyball (which would both be infinite quantities but differ by a finite amount), and another $M_{\text{buckyball}}$ so that the total energy in that region of space is
$$M_{\text{buckyball}}c^2 - \int_{\text{interior volume}} \rho_{\text{reduced energy density}} $$
In principle this could be experimentally measured (the gravitational pull perhaps of the buckyball would be slightly less than what you would expect). Is this thought experiment consistent?
