Will ET write or radiate: inscribed matter vs electromagnetic channels

We consider the energy requirements of information carriage using physical transport of inscribed matter and compare it to that using electromagnetic radiation when delivery delay beyond light transit time can be tolerated. Somewhat counter-intuitively, physical transport of inscribed matter is often more energy efficient than electromagnetic broadcast by many orders of magnitude over a wide range of scenarios-from chip-to-chip computer communications to interstellar signaling. In fact, the efficiencies are so enormous that it may even be more likely for initial contact by extraterrestrial civilizations to occur using physical artifacts -essentially messages in a bottle-than via electromagnetic communication.