 Psst. Could you help the Dyson sphere with this homework? It's not very bright. Okay, let's get it out of our system so we can move on with our lives. Aliens. The search for extraterrestrial intelligence is something that nerds like myself think about a whole lot, but why? What's the big deal? Is it just the nerdy equivalent of thinking about things like unicorns or fairies, just an idle daydream? Well, the truly insane number of planets in our universe and the relative simplicity of the evolutionary process are good reasons to be optimistic about something called life appearing somewhere else in the universe. I mean, with that many poles on the slot machine, you're bound to win more than once. But why the focus on finding other life? I mean, what would the discovery of alien bacteria swimming in the methane on Titan mean for our lives? Well, many instrumental technological and scientific discoveries have been the result of observation of other life forms here on earth. The massive testing facility of life on this planet has developed a whole bunch of very interesting solutions to complex problems. Those solutions often act like shortcuts for us to understand the underlying principles of the operation of the universe and how to exploit them. Antibiotics, genetic algorithms, biomaterials, there's a whole lot of really cool stuff that we've gotten out of simply observing how life on this planet evolved and the wide diversity of tricks that it's developed to survive. The usefulness of those tricks is frequently correlated with just how weird the species that we're looking at is. Like, we're not going to learn a whole lot by dissecting chimps or apes because they're more or less like us inside. But hagfish? Whaaat? Unfortunately, all life on earth, as far as we can tell, evolved from one common ancestor. One set of self-replicating chemical interactions gave rise to every single living thing here. And as different as we are from mushrooms, if you trace our family tree far enough back you'll find that we're actually distant cousins. A few times removed. In some sense, that limits just how much insight we can glean from observing living things. Even with all the weird crap we've got here on earth, we've only ever seen life develop in one particular way, which means that we're operating from one data point. That leaves us with all sorts of interesting questions that we don't have any reasonable answers to. Like, is DNA the best mechanism for life in general? There are some good reasons to think so. I mean, every life form here on earth uses it in one way or another. It uses elements which are commonly found throughout the universe. The double helix seems like a good way to do error correction. But there are some good reasons to think otherwise. Four nucleotides seems like an arbitrary number. Why not six or eight? There are all sorts of other ways to encode self-replicating information chemically, so maybe life elsewhere uses one of those. Maybe DNA is actually a really crappy basis for life, and all of their life in the universe uses something that's less prone to cancer. Who can say? Again, we're only working from one data point here. If we were to find even the most primitive life forms on some other planet, then we'd have exponentially more information to answer questions like these. But for right now, we have precisely zero clues. Also, it's kind of a pain in the neck to visit a bunch of different planets and search them for life. I mean, ideally, they'd call us. Which is part of the motivation for the search for extraterrestrial intelligence, along with the fact that if the diversity of earth life is insufficient to answer these very interesting questions about biology, the diversity of earth intelligence is abysmal, and so is our understanding of intelligence. Anthropologists, sociologists, linguists, and the like can talk at length about the fascinating variety of human thought. Studying various weird human cultures has given us tremendous insight into how our minds can work, very much in the way that studying weird species has given us insight into life and nature. But if you trace them back far enough, all of those myriad cultures stem from the same basic version of intelligence that evolution came up with first. There might be any number of interesting and very useful ways of thinking, which we've never had the chance to develop, just by the luck of the draw. You won't find a human culture which forbids the consumption of anything but solar energy, or which solves math problems by counting the lobes on its swim bladders. Our intelligence, as awesomely weird as it can get here on earth, is still intrinsically human. In that light, finding an intelligent alien species would be a massive jackpot, not only would we get useful information about biology, but also everything from philosophy and metaphysics to linguistics and sociology. We'd know a lot more about the sort of things which were necessary for intelligence, and which are just artifacts of the process which resulted in our particular version of it. But that's just the tip of the iceberg. The search for extraterrestrial intelligence has only been going on in earnest for a little less than 100 years, since the discovery of radio. In astronomical terms, that's nothing. On the time scale of planets and stars, we've only just figured out how we might be able to talk to alien species. If there's any sort of interstellar relay chat, we're total noobs. That implies that anyone who we could talk to will have been using radio waves for much longer than we have, and is probably much further up the tech tree. So on top of the massive boon to our understanding of biology and intelligence, we might also get to crib off of someone who's a few hundred years ahead of us. That would be awesome. Unfortunately, we've got a limited set of resources to work with here. It's not like we're going to build a bunch of super powerful antennas to blast the universe with radio waves in the hope that someone's willing to lend us their physics homework. If we wanted to get in touch with an alien species who was smarter than we were, we would probably have to know where to look first. And we really don't have much to go on here. At the beginning, we were just trying to dream up what alien life might be like. Now we're trying to predict what an alien life form with alien biology and a superior alien intelligence would do. This is a serious stab in the dark. But it could be really cool, so let's give it a shot. From what we know about life and evolution, it helps to have some sort of energy input that fuels the evolutionary process. Some sort of battery that powers life and allows it to gradually increase in complexity. For us, it's the sun, and it's probably a good guess that it's the same for alien species. Stars put out an immense amount of easily harnessed energy, so we should probably look around stars. Actually, if you look at the history of human civilization, we're using more and more of that solar energy over time. I mean, we started by just using it to grow plants and feed livestock, but as we become more technologically capable, we're using an increasing amount of that power directly. Solar panels are springing up on everything from your grandma's roof to backpacks. Solar farms are pumping out gigawatts of electrical power. The Japan Aerospace Exploration Agency even has plans to build massive mirrored satellites out in space to harness solar energy directly, where it hasn't been weakened by Earth's atmosphere or magnetic field, and then beam it back down here where we can use it. That trend peaked the interest of theoretical physicist and mathematician Freeman Dyson, who ran a little thought experiment. If an intelligent technologically sophisticated alien species wanted to harness even more of that power, to run giant supercomputers, huge spacecraft, radio signals, whatever, how would they do it? Well, they might develop any number of energy technologies. But I mean, the star is right there. Dyson suggested that an advanced alien species would do more or less what the Japanese plan to, build some sort of structure out in space to harness additional solar energy. But instead of a couple of mirrors parked around Earth, he imagined something more like this. After all, why would they limit themselves to the planet? That's for noob species like humans. The more satellites they have encompassing the star, the more of that energy they can harness before it goes flying off into the cosmos, so they can use it to power whatever the alien version of Pokemon Go is. So, if we were looking to chat with an alien species that was advanced enough to build some badass orbital solar collectors, we might look for giant stars that aren't putting off quite as much light as we'd expect them to. The laws of thermodynamics forbid collecting 100% of a star's energy output. There has to be some amount lost to waste heat, no matter how efficient the collectors are. But with most of the high energy starlight captured, what we'd see would be a lot of low energy infrared radiation instead. The more advanced the civilization, the more satellites they'd be able to orbit, and the more starlight they'd be able to capture. If they really needed to fuel that poke fever, it might even be possible to completely envelop the star in energy collectors, something now called a Dyson Sphere. Again, this is a seriously rickety set of assumptions. We're so far out in the weeds that we've lost cell service and were hacking at vines with a machete. It would be mostly unsurprising if this whole chain of speculation described nothing that actually exists in the universe. But we have observed a few stars that have some peculiar characteristics that are reminiscent of Dyson's suggestions. It's pretty long odds that beaming bursts of radio signals at those stars will put us in touch with an advanced alien intelligence, but hey, one would be enough. Of course, there might also be some good reasons not to contact them. But let's be real, who do you think is running those radio antenna arrays? Star Trek fans. What would the discovery of an intelligent extraterrestrial species mean for you? What do you think of Dyson's pie slice in the sky ideas? Please leave a comment below and let me know what you think. Thank you very much for watching. Don't forget to blah blah subscribe, blah share, and don't stop thunking.