Noah Brier | August 5, 2019

Why is this interesting? - The Fermi Paradox Edition

On aliens, intelligence, and the universe

Noah here. At this point I’m sure you’ve heard that some people may or may not be planning to raid Area 51 in September and the military isn’t super excited about the idea. My guess is nothing happens, but the more interesting question, obviously, is are we all alone in the universe? This question sits at the center of The Fermi Paradox, which suggests that it’s very strange we haven’t run into any aliens considering the high likelihood for intelligent life to exist elsewhere in our vast universe. Here’s a brief explanation of the math from Tim Urban of Wait But Why:

As many stars as there are in our galaxy (100 – 400 billion), there are roughly an equal number of galaxies in the observable universe—so for every star in the colossal Milky Way, there’s a whole galaxy out there. All together, that comes out to the typically quoted range of between 1022 and 1024 total stars, which means that for every grain of sand on every beach on Earth, there are 10,000 stars out there. … [Of those there are about] 500 billion billion sun-like stars. … There’s also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say it’s as high as 50%, but let’s go with the more conservative 22% that came out of a recent PNAS study. That suggests that there’s a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets.

“So,” Urban writes, “there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach.” 

Why is this interesting?

While there are a bunch of folks who take this stuff fairly seriously, I just think it’s a pretty fun thought experiment with lots of fascinating theories. One of the more popular explanations is called the Great Filter, which basically posits that either it’s incredibly rare to reach mass intelligence like humans have on earth, we’re just the first to do it, or that we’re all about to kill each other any day now and that explains why we haven’t heard from any other space civilization. Here’s an illustration of the idea from Urban’s explainer:

That’s just one of a whole bunch of attempts at explaining why the math doesn’t line up with the observational data. One of my favorites, mostly for its absurdity, is called the “Aestivation Hypothesis”. Aestivation is the opposite of hibernation (sleeping during the summer instead of winter) and the gist of the hypothesis is that maybe the reason we haven’t heard from the aliens is because they’re waiting for the stars to die out so it gets cold enough that they can efficiently run massively complex calculations that would otherwise take tons of power to keep cool. Here’s how Anders Sandberg, one of the academics behind the idea, explained it on the 80,000 hours podcast:

So if you imagine the real advanced civilization that has seen a lot of galaxy expanded long distances, once you’ve seen a hundred elliptical galaxies and a hundred spiral galaxies, how many surprises are we going to be there? Now most of the interesting stuff your civilization is doing is going to be culture, science, philosophy, and all the other internal stuff. The external universe is nice scenery, but you’ve seen much of it. So this leads to this possibility that maybe advanced civilization is actually an estimate. They slow down, they freeze themselves, and wait until a much later era because we get so much more. It turns out that you can calculate how much more they can get. So the background radiation of the universe is declining exponentially.

I think I just want to believe this one because it makes me laugh. (NRB)

Bathroom of the Day:

This was floating around Twitter, so maybe you saw it. Christopher Niemann, an illustrator that frequently works for the New Yorker, was moving to Berlin from New York and designed the below subway-tile bathroom for his MTA-obsessed kids. It’s awesome, but the best part has to be his son’s reaction: “When first showed it to my then 6 year old, he looked at it for 20 secs, then said ‘the JMZ trains are missing’ turned around and left.” (NRB)

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Thanks for reading,

Noah (NRB) & Colin (CJN)

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