As you’re no doubt aware, humans are a rather noisy species. Not just audibly, like in the case of somebody talking loudly when you’re in a movie theater, but also electromagnetically. All of our wireless transmissions since Marconi made his first spark gap broadcast in 1895 have radiated out into space, and anyone who’s got a sensitive enough ear pointed into our little corner of the Milky Way should have no trouble hearing us. Even if these extraterrestrial eavesdroppers wouldn’t be able to understand the content of our transmissions, the sheer volume of them would be enough to indicate that whatever is making all that noise on the third rock orbiting Sol can’t be a natural phenomena. In other words, one of the best ways to find intelligent life in the galaxy may just be to sit around and wait for them to hear us.
Of course, there’s some pesky physics involved that makes it a bit more complicated. Signals radiate from the Earth at the speed of light, which is like a brisk walk in interstellar terms. Depending on where these hypothetical listeners are located, the delay between when we broadcast something and when they receive it can be immense. For example, any intelligent beings that might be listening in on us from the closest known star, Proxima Centauri, are only just now being utterly disappointed by the finale for “How I Met Your Mother“. Comparatively, “Dallas” fans from Zeta Reticuli are still on the edge of their seats waiting to find out who shot J.R.
But rather than relying on our normal broadcasts to do the talking for us, a recent paper in The Astrophysical Journal makes the case that we should go one better. Written by James R. Clark and Kerri Cahoy, “Optical Detection of Lasers with Near-term Technology at Interstellar Distances” makes the case that we could use current or near-term laser technology to broadcast a highly directional beacon to potentially life-harboring star systems. What’s more, it even theorizes it would be possible to establish direct communications with an alien intelligence simply by modulating the beam.