Alien Contact

And even those who believe in a government conspiracy over UFOs could hardly claim the same for SETI. A signal from space is not something you can stack up in a secret hangar or hide behind six layers of barbed wire in the desert. A SETI signal can be easily confirmed and will be impossible to hide. There was a parallel in the seventeenth century. When clerics forced Galileo to desist from publishing his discoveries of Jupiter’s large moons (a strong proof that the Earth was not the center of the Universe), he reputedly swallowed hard and muttered that "still, it moves." In other words, the evidence for his discovery was sitting in the sky awaiting confirmation by anyone with a cheap telescope and a few minutes’ time. The same is true of a SETI signal: the word will be out, and fast.

Australia National Telescope Facility The Parkes Telescope in Australia is part of SETI's SERENDIP programme

Alien hardware

Of course, it’s also conceivable that we will find not a signal, but alien artifacts. Imagine that Hubble or some other large telescope accidentally captures an image of the exhaust radiation from an interstellar rocket. Or perhaps we will trip over colossal feats of astro-engineering involving the rearrangement of an alien society’s entire planetary system. Such discoveries would undoubtedly be reported just as quickly as a SETI signal. The consequences, to my mind, would also be similar: a mammoth news story, inspiring follow-up research by just about every astronomer on the planet.

If the artifact were right on our doorstep, however, it would trigger a different response. We might – as suggested by Arthur C. Clarke - discover a purpose-built monolith on the Moon. Another intriguing possibility is that we could find a time capsule at one of the Lagrangian points – gravitational dead spots in the Earth-Moon system where an alien memento could float in endless space storage. Perhaps we’ll suddenly uncover an interstellar probe hanging out in our Solar System, or maybe the aliens will actually land at 10 Downing Street and demand satisfaction.

Such scenarios are entirely different (and, to my mind, enormously less probable) than the SETI success that I am considering here. They would provide physical evidence we could cart to the lab and – in the case of alien visitation – might confront us with a lethal threat. Some of the social researchers who consider what will happen if we find ET point to historical analogs such as Orson Welles’s 1938 War of the Worlds radio broadcast, which panicked many people on the US East Coast. Such an apocalyptic reaction might follow a close encounter of the physical kind. But a microwave radio signal or a flashing infrared light beam, reaching us from hundreds or thousands of light-years away, is no reason to board the windows and head for the hills.