First off, I know nothing about physics so if this question seems bizarre, that's probably why! In theory, are there conditions that would permit electromagnetic energy to block or limit the passage of oxygen (normal, everyday oxygen levels)? Is electromagnetic energy denser than oxygen under some circumstances? I've found that the density of oxygen is 1.429 kg/m(to the power of)3 at 0 C, but the density of electromagnetic energy is more complex (if it is even comparable to that of oxygen). I've discovered that the total electromagnetic energy (EME) density is the sum of u(subscript)e and u(subscript)m. These specify at any time how much electromagnetic field energy there is at any point -- but what if it was over a certain amount of space (i.e. many points)? Does the density of EME depend on the size of the wavelength? I'm at a loss... Any help would be appreciated, even if it's just to say "This doesn't make any sense!"