We’ve all dreamed of what contact with an alien race might look like. Would it be like, well, Contact–a benevolent but inscrutable alien intelligence that decides we aren’t ready yet for the stars? Would it be a cosmic farce like Hitchhiker’s Guide to the Galaxy? Or would we straight-up be in an Alien film?
We now have a better idea of how many possible alien civilizations there might be to contact. The answer is both very specific and kind of a bummer.
Tom Westby and Christopher Conselice, of the University of Nottingham, reexamined the Drake equation to consider whether there’s anyone out in space listening. The scientists described the Drake equation, which was first posited by Frank Drake 60 years ago, as “a tool for estimating the number of planets in our galaxy that host intelligent life with the capability of releasing signals which could be detectable from Earth.”
Westby and Conselice expanded on the Drake equation to figure out how many stars are old enough to allow the billions of years it takes to develop intelligent life, the raw materials to produce technology as we understand it, and the habitat to support lifeforms.
Their grim conclusion is that just 36 alien civilizations could be our intergalactic pen pals. And those closest of them is 17,000 light-years away. That means even if we manage to send a signal out there, we’ll be waiting a long time for a reply.
Civilization as we know it here on Earth is only about 6,000 years old. We’ve only been broadcast information in the form of radio waves for about 100 years. The truth is that we have no idea how long our civilization will last, or whether we’re a typical example of life in the universe or an anomaly.
“The lifetime of civilizations in our galaxy is a big unknown,” Westby and Conselice note. “It is clear that … very long lifetimes are needed for … the galaxy to contain even a few possible active contemporary civilizations.”
The longer any civilization lasts, the more chances they’ll have to invent technology to communicate with other planets and travel through the stars. However, that assumes any other intelligent life exists or has existed in our galaxy.
Westby and Conselice are big fans of the Astrobiological Copernican Principle, which is a very fancy way of saying that, given enough time and favorable conditions, life is bound to form on a planet that can support it.
For them, the question isn’t so much whether life exists, but whether it exists at just the right time for us to slide into the DMs.
We might only have 36 neighbors–and I really hope none of them want to use my Disney+ password to watch Hamilton. However, scientists have developed a new way to look for life in the stars.
Most often, we look for biosignatures. Those include things like gases, minerals, and other biological clues that life existed on a planet. Biosignatures could show us that there are–or were–anything from a handful of microorganisms on a planet to a full-fledged society of intelligent beings.
However, in 2018 NASA announced a plan to focus on technosignatures. These focus solely on intelligent life–the kind that we might be able to talk to. We begin by assuming that aliens have to abide by the same laws of physics as we do. As Adam Frank of the University of Rochester pointed out, “There are only so many forms of energy in the universe. Aliens are not magic.”
Once we start searching for technosignatures, we will (hopefully) be able to figure out which 36 planets out there host life.