Are we alone in the universe? It’s a question whose answer—whether it’s yes or no—would philosophically and scientifically rock our world to the core.
To find out, scientists have long been turning powerful radio telescopes to the cosmos. The theory is that, like us, other intelligent species are perhaps broadcasting radio signals with the distinctly “unnatural” signature of a technological civilization.
But despite decades of intent listening, we’ve yet to pick anything up. Even in a recent survey of 10 million stars by the Murchison Widefield Array radio telescope in Western Australia—one of the most extensive to date—scientists found nothing of note.
Where is everyone?
Theories abound, but one possibility is we simply haven’t looked enough. Our galaxy, with its hundreds of billions of stars and countless planets, is a very big place. The scientists conducting the Murchison survey said it was like searching an area the size of a swimming pool in the ocean. In our search for a needle, maybe we just need to sift more straw.
But there’s a problem.
Our own civilization’s ceaseless radio chatter—which, in theory at least, would be similar to the signals SETI’s searching for—is growing louder, making it much harder for scientists to filter out local noise. While researchers have techniques and software to remove human signals, some are suggesting a more radical solution. Might we escape the noise entirely?
The further from civilization you go—Australia’s outback or Chile’s Atacama desert—the more the chatter fades. And if you keep following this line of reasoning to its end, you’ll land in a place with the most profound silence of all: the far side of the moon.
It’s no surprise, then, that scientists have been dreaming of an observatory on the moon for years. Equally unsurprising is the fact no such observatory yet exists.
But a recent paper—written by Breakthrough Listen sponsored researchers Eric Michaud, Andrew Siemion, Jamie Drew, and Pete Worden—makes the case for a SETI (search for extraterrestrial intelligence) observatory on the moon or in lunar orbit. And notably, they suggest that such a project is, perhaps, for the first time approaching feasibility.