In China, lightRadio Metro Radio will be deployed in busy indoor and outdoor locations, such as shopping malls and stadiums where coverage can suffer either from the large number of consumers trying to access a network, or because the density of buildings impedes the radio signal.
But it is possible to detect minute deviations in this signal, and these fluctuations - seen as mottling in the map - are understood to reflect the differences in the density of matter when the light parted company and set out on its journey all those years ago.