I suspect that they communicate in ways that we can conceive of, and have recently started to communicate, ourselves.
Specifically, if you're broadcasting radio or TV signals that look like anything other than random noise from the perspective of an uncorrelated receiver, then you're wasting energy. Human history suggests that there's a window of about 100 years between the time when a civilization learns RF theory and starts to generate coherent signals, and the time when they learn information theory and stop.
Specifically, if you're broadcasting radio or TV signals that look like anything other than random noise from the perspective of an uncorrelated receiver, then you're wasting energy. Human history suggests that there's a window of about 100 years between the time when a civilization learns RF theory and starts to generate coherent signals, and the time when they learn information theory and stop.