Warning: extremely nerdy content, harmful if taken seriously
Today I’d like to share a nerd thought experiment with you people, and since many of you are already deeply nerdy, pardon me if you’ve already thought about it. Feel free – no really, I encourage you – to argue strenuously with me if I’ve misrepresented the current thinking on this. That’s why I have comments!!
It’s called the Fermi Paradox, and it’s loosely speaking a formula that relates the probability of intelligent life somewhere besides here on earth, the probability of other earth-like planets, and the fact that we haven’t been contacted by our alien neighbors.
It starts with that last thing. We haven’t been contacted by aliens, so what gives? Is it because life-sustaining planets are super rare? Or is it because they are plentiful and life, or at least intelligent life, or at least intelligent life with advanced technology, just doesn’t happen on them? Or does life happen on them but once they get intelligent they immediately kill each other with atomic weapons?
- N = the number of civilizations in our galaxy with which radio-communication might be possible (i.e. which are on our current past light cone)
- R* = the average rate of star formation in our galaxy
- fp = the fraction of those stars that have planets
- ne = the average number of planets that can potentially support life per star that has planets
- fl = the fraction of planets that could support life that actually develop life at some point
- fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
- fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
- L = the length of time for which such civilizations release detectable signals into space
So the bad news (hat tip Suresh Naidu) is that, due to scientists discovering more earth-like planets recently, we’re probably all going to die soon.
Here’s the reasoning. Notice in the above equation that N is the product of a bunch of things. If N doesn’t change but our estimate of one of those terms goes up or down, then the other terms have to go down or up to compensate. And since finding a bunch of earth-like planets increases some combination of R*, fp, and ne, we need to compensate with some combination of the other terms. But if you look at them the most obvious choice is L, the length of time civilizations release detectable signals into space.
And I say “most obvious” because it makes the thought experiment more fun that way. Also we exist as proof that some planets do develop intelligent life with the technology to send out signals into space but we have no idea how long we’ll last.
Anyhoo, not sure if there are actionable items here except for maybe deciding to stop looking for earth-like planets, or deciding to stop emitting signals to other planets so we can claim other aliens didn’t obliterate themselves, they were simply “too busy” to call us (we need another term which represents the probability of the invention of Candy Crush Saga!!!). Or maybe they took a look from afar and saw reality TV and decided we weren’t ready, a kind of updated Star Trek first contact kind of theory.
Update: I can’t believe I didn’t add an xkcd comic to this, my bad. Here’s one (hat tip Suresh Naidu):