Humanity may be alone in the universe

But that’s where our optimism, if we’re being scientifically honest and scrupulous, ought to end. Because there are three big steps out there, in order to get a human-like civilization, that need to happen:

1. The step of abiogenesis — where the raw ingredients associated with organic processes actually become what we recognize as “life” — needs to occur.

2. Life must survive and thrive for billions of years on a planet in order to evolve multicellularity, complexity, differentiation and what we call “intelligence.”

3. And finally, that intelligent life must then become a technological civilization, either gaining the ability to announce its presence to the Universe, to reach out beyond its home and explore the Universe, or to reach the stage where it can listen for other forms of intelligence in the Universe. Or, more optimistically, all three…

Today, Adam Frank argues that it’s unrealistic to give these three steps a combined probability of less than 10^-22, and therefore concludes that there must have been aliens elsewhere in the Universe. But this is itself a preposterous claim, based on no evidence whatsoever. Abiogenesis may have been common; it may have occurred multiple times on Earth alone, or on Mars, Titan, Europa, Venus, Enceladus, or elsewhere even in our own Solar System. Or it may be such a rare process that even if we created a hundred clones of a young Earth — or a thousand, or a million — our world might be the only one where it occurred.