Where is everybody?
For decades that question was merely a part of physics legend, the kind of thing grad students overhear when their advisors take them out to dinner. But the story behind that question is true, and it’s a good one. It was the late 1940’s, soon after the close of World War 2. The world was buzzing with reports of UFO’s, flying saucers, and aliens sticking their probes where the sun don’t shine.
Physicists can sometimes resemble real people, and like real people when they get together for lunch at work they like to chat about whatever’s in the news. And one time, famed physicist Enrico Fermi was visiting his colleagues at Los Alamos National Laboratory. Right down the road from Roswell. The conversation turned to UFO’s, and the group, including Fermi, started speculating wildly, quickly coming to the realization that the only feasible way that UFO’s could be aliens would be if faster-than-light travel was possible. But during the conversation, Fermi fell silent.
Sometime later, as the conversation shifted to other topics, Fermi suddenly blurted out, “Where is everybody?”
Everyone at the table immediately knew what we meant.
That lunchtime exclamation became the core what we call today the Fermi paradox. Here’s the basic deal: life is possible in the universe. Need proof? Hello, nice to meet you. It happened here on Earth, and the universe tends to not just do things only once. In fact, the default assumption in astronomy and cosmology is that we’re not special – we occupy no privileged position and we have no unique status (sometimes called Copernican principle for his removal of the Earth from the center of the universe). And indeed, nothing about our planet is all that remarkable: it’s just another lump of oxygen and carbon orbiting just-another-star. Heck, even our preliminary estimates suggest that there are something around 5 billion duplicates of the Earth in the Milky Way alone.
That’s 5 billion chances for life to arise under identical conditions.
So by that logic, the universe should be teeming with life. and not just regular life, intelligent life, and not just intelligent life, but space faring, and even space colonizing life! We can again point to ourselves as an example: we are right on the cusp of a sustained presence in space (like, in a real way), and it’s not hard to imagine that by extending our technology just a little bit, we could be one of those, I don’t know, star trek civilizations.
So if we could do it, then somebody else should be able to do it too.
You can even imagine throwing every technological hurdle in our way – nothing better than fusion-powered rockets, always constrained by the speed of light, limited lifespans, disease, warfare, anything that would and could slow down our progress, the works. But the fact is that our milky way galaxy is roughly 10 billion years old, and given that enormous amount of time, then space-faring civilizations have had more than enough eons to essentially spread throughout the entire galaxy, even doing it the slow way.
We should see advanced civilizations everywhere. We’re talking Dyson spheres, stellar engineering, or signatures of powerful engines. And while we do see many mysteries out in the universe – unexplained explosions or strange particles zipping by, we see no need to explain ANY observation in the solar system, galaxy, or universe, by invoking advanced alien civilizations. Even when our natural “dead” explanations don’t explain everything (cough FRBs, dark energy, hexagon on Saturn), we find no great pressure to say ALIENS DID IT.
Even leaving astronomical observations aside, given the abundance of life and intelligent civilizations, plus the raw amount of time they’ve had to poke around the galaxy, our solar system should have been visited MULTIPLE times by MULTIPLE species, either in person (or in-alien) or with their robotic craft. We should have monoliths and nanobots and space jockey skeletons everywhere, especially on the airless worlds that have maintained a record of impacts and events going back over four billion years.
So…where is everybody?
Hence the paradox: something in this line of reasoning has to give. We’ve got one, if not many – if not all – of these statements wrong. But which one?
Now, I would love to do an entire series on the fermi paradox and all its possible answers and what that means for current searches for life, but I’ll save that for a future date (and please, if more of you ask about it RIGHT NOW the sooner I’ll get to it).
But to slake your thirst for solving long-standing puzzles in physics, we’ll spend today jumping into one of the possible resolutions to the fermi paradox, the so-called GREAT FILTER.
Which sounds…kinda ominous. And…is…kinda ominous. But as we’ll see, it doesn’t HAVE to be ominous, but…sigh…it probably is.
