Adam Frank: preference

Transcript context

…And they die, kill themselves all somehow. Anyway. So just how do we find them? Yeah. So SETI, Search for Extraterrestrial Technology is a term that I am not fond of using anymore. Some people in my field are. So I’m sorry folks, but what I really like is the idea of technosignatures because I think to me, SETI is the… First of all, intelligence. We’re not really looking for intelligence. We’re looking for technology, and SETI, the classic idea of SETI is the radio telescopes and contact, Jodie Foster with the headphones. That whole thing is still part, it’s still active, there’s still great things going on with it, but suddenly, this whole new window opened up. When we discovered exoplanets, we now found a new way to look for intelligence civilizations or life in general in a way that doesn’t have any of the assumptions that had to go into the classic radio SETI. And specifically, what I mean is we’re not looking for somebody sending us a beacon. You really needed that with a classic model, for a bunch of different reasons. You have to assume they wanted to be found and they were sending you a super powerful beacon. Now, because we know exactly where to look and we know exactly how to look, we can just go about looking for passive signatures of the civilization, going about its civilizationing business, without asking whether they want to be contacted or not. So this is what we call a biosignature or a technosignature. It is an imprint in the light from the planet of the activity of a biosphere or a technosphere, and that’s really important. That is why the whole Gaia idea ends up being astrobiological, that biospheres and technospheres are so potent, they change the entire planet, and you can see that from 20 light years. So let’s give an example of a biosignature to start off with, which would be a signature of a biosphere, oxygen. Right? On earth at least, we know that oxygen is only in the atmosphere because life put it there. If life went away, the oxygen, and particularly oxygen and methane, that pair, they would disappear very quickly. They’d react away. They’d all be gone. So if you find a planet with oxygen and methane, that’s a good bet that there’s a biosphere there. Okay, what about technospheres? Technospheres, so I’m the principal investigator on the first grant NASA has ever given to do these exoplanet technosignatures. For reasons we can talk about, NASA had gotten pretty gun-shy about funding anything about intelligent life, but okay. What’s an example of a technosignature? Well, one could be atmospheric, “Pollution.” I’m going to put, “Pollution,” in quotes here because it doesn’t have to be pollution, but gases like chlorofluorocarbons. an example of a technosignature? Well, one could be atmospheric, “Pollution.” I’m going to put, “Pollution,” in quotes here because it doesn’t have to be pollution, but gases like chlorofluorocarbons. So we dumped a huge amount of chlorofluorocarbons into the atmosphere by mistake. It was affecting the ozone, but we put so much in there that actually, this is one of the things we did, we did a paper where we showed, you could detect it across interstellar distances. You could look at the atmosphere, look at the light coming from a distant planet, pass the light through a spectrograph and see the spectral lines, the fingerprint, the spectral fingerprint of chlorofluorocarbons in an atmosphere. And that would for sure tell you that there was a technological civilization there, because there’s no other way to make chlorofluorocarbons except through some kind of industrial process.…

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