Light trick can retrieve missed messages
Even if photons pass you by, you can snatch signal from their electromagnetic wake
By Andrew Grant
SAN ANTONIO — Light may travel at the speed of light, but the information it carries doesn’t have to. Three physicists have proposed a way to receive light-based messages even when the light itself has already flown by.
The communication technique, detailed March 2 at the March meeting of the American Physical Society and in a paper to be published in Physical Review Letters, relies on measuring electromagnetic echoes that arise upon the generation of light. Although the method has limited practical use for now, it offers an intriguing exception to the idea that sharing information via light requires one party to send photons and the other to absorb them. Eventually, the technique could enable astronomers to glean details on distant stars and galaxies without directly measuring their light.