If the aliens are out there, where are they?

More pessimistically, biologically-based intelligence may constitute only a very brief phase in the evolution of complexity, followed by what futurists have dubbed the “singularity”—the dominance of artificial, inorganic intelligence. If this is indeed the case, most advanced species are likely not to be found on a planet’s surface (where gravity is helpful for the emergence of biological life, but is otherwise a liability). But they probably must still be near a fuel supply, namely a star, because of energy considerations. Even if such intelligent machines were to transmit a signal, it would probably be unrecognizable and non-decodable to our relatively primitive organic brains.

This could perhaps explain the Fermi paradox. If this scenario holds true, our chances of detecting simple life via biosignatures may be far greater than those of discovering intelligent ET’s. Still, the ultimate goal of detecting the signature of an advanced intelligence, whether biological or nonbiological, remains the most intriguing option. All power to proposed projects for the 2020s such as Japan’s Space Infrared Telescope for Cosmology and Astrophysics (SPICA) and NASA’s Far Infrared Surveyor.

The key point is that for the first time in human history, we are only two or three decades away from being able to actually answer the “Are we alone?” question. Because the answer may affect nothing less than our last claim for being special in the cosmos, its importance cannot be overemphasized.