We have been talking about new planets for, let’s see, about 21 years, ever since Swiss astronomers found one orbiting 51 Pegasus in 1995. Now we know that the universe is full of planets; they’re a routine element of star formation. At this point, it’s easy to get a little jaded about a new planet discovery. But today’s announcement is pretty cool: The very nearest star, Proxima Centauri, has a roughly Earth-size planet orbiting at a distance where water could plausibly be liquid at the surface. Read Rachel Feltman’s report on the big discovery.
I’ve added a sidebar that notes that this is not a very Earth-like place, and no one should expect to relocate there anytime soon. Message: We’re Earthlings. Get used to it.
These new exoplanet discoveries have made us adjust our personal Drake Equations. And of course we’ve all gnawed on the Fermi Paradox.
As ever, I will remind people that we have no data about extraterrestrial life. None. It’s all speculation. And we should guard against our natural desire for life to be out there. Life resonates with life. We don’t want to be alone in the universe. I don’t think we are, but that’s just an arm-waving opinion without any evidence to back it up.
There’s a line in Carl Sagan’s novel “Contact” (and maybe it’s also in the movie?) where a character says: “The universe is a pretty big place. If it’s just us, seems like an awful waste of space.” Sagan’s cosmology was shaped around what he called the Assumption of Mediocrity, which is kind of like the Copernican Principle: He believed humans are but a local example of a cosmic phenomenon and that there’s nothing special about us. He went on to argue that any civilization with which we might make contact would be far superior to us technologically, because we had just learned in the past few years how to communicate at interstellar distances, and other civilizations would likely have been doing it a long time. He made this point at a 1972 conference in Boston:
“There is almost certainly no civilization in the galaxy dumber than us that we can talk to. We are the dumbest communicative civilization in the galaxy.” [“Captured by Aliens," Simon & Schuster, 1999, by J.A., page 55]
But even this Assumption of Mediocrity carries with it a belief — almost a prejudice, or maybe you’d just call it a wish — that life, where it exists, will often evolve to the point where a species will be intelligent, and technological and communicative. That’s several great leaps in succession.
Remember that life on Earth remained single-celled for several billion years. Given enough time, life can become what we define as intelligent — we know this from our sample of one — but there’s no way to calculate how frequently that happens.
And although life seems to be made out of stuff that’s just lying around everywhere, it’s obviously not something that pops up automatically on a planet or moon — because we don’t see that in our own solar system. We don’t know how it originates and don’t really have a solid definition of life.
Proxima b is only a few million miles from its parent star, Proxima Centauri, and has probably been regularly blasted with flares of radiation. It might still have an atmosphere, but scientists aren’t sure about that, and there’s a robust debate about whether planets orbiting the very common red dwarf stars are habitable in general.
If you look at the whole bestiary of planets out there — all the hot Jupiters and mini-Neptunes and super-Earths and these red dwarf planets and whatnot — you will see a lot of places where life probably doesn’t exist, at least not for very long. In fact, life may be a fringe element in this universe. We don’t know. Your argument is as good as mine. But the universe doesn’t seem to be about us in any obvious way. And it doesn’t seem to be about life, particularly. If the universe had a mind, you’d say it appears to be agnostic about life.
All of which is a reminder to thank our lucky star that we have such a wonderful home.