Ether

World Wireless System was intended to transmit energy through the ether. Nikola Tesla considered 50000 dollars a small price to pay to transmit energy through the ether with no wires. (TV: Nikola Tesla's Night of Terror)

Behind the scenes
According to Inside a Skaro Saucer, which is not considered a valid source by this wiki, "light ions in the ether" were the means by which the Daleks' Rad-etheric magniscopes were able to "see" at a distance of over a million miles.