Write or radiate? [information flow]

We consider information flow via physical transport of inscribed media through space and compare it to information flow via electromagnetic radiation. Somewhat counterintuitively for point to point links, physical transport of inscribed mass is often energetically more efficient by many orders of magnitude than electromagnetic broadcast. And perhaps more surprising, even in a broadcast setting (depending on the receiver density) inscribed mass transport is still energetically more efficient. We examine these results for terrestrial telecommunications as well as point to point and broadcast communication over great distances with loose delay constraints.