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Rationally speaking, is a presentation of New York City skeptics dedicated to promoting critical thinking, skeptical inquiry and science education. For more information, please visit us at NYC Skeptic's Doug. Welcome to Only Speaking the podcast, where we explore the borderlands between reason and nonsense, I am your host, Masimo People YouTube. And with me, as always, is my co-host, Julia Gillard. Julia, what are we going to talk about today?


Masimo, our topic today is Saidee, the search for extraterrestrial intelligence.


We're going to talk about whether it's solid science, pseudoscience or something else and about some of the philosophical and scientific questions that study raises.


Sounds good. Well, it's not pseudo science, is it? But what do you think?


Those are your words. Let's go to you there. Well, I was raising the question, but I think we can get the pseudoscience out of the way, right? I mean, it's not in the same ballpark as, say, astrology or UFO, although UFOs is kind of related.


It's a topic. Right.


So you covered this topic in one of my favorite chapters, actually, from your book, Nonsense on Stilts. Right. In which you talk about study as one of several sort of gray area, murky borderline cases of science.


And I mean, my off the cuff take was that it's not it's sort of a category error to ask whether it's science because it's not actually making empirical claims. It's simply looking for something.


So I'm used to evaluating the sort of scientific status of of empirical claims about the world, like how substantiated are these claims?


What evidence do they use? You know, are they logically coherent?


But the the endeavor of looking for something or trying to create something or build something seems different than, you know, fields that are claiming things.


Well, I see the point, except that I do think that theory makes a claim, or at least it starts with one hypothesis or it starts with the hypothesis that there is more than one example of technological civilization out there in the universe that it's possible.


Right, right.


OK, so so in other words, there is a hypothesis underlying. In fact, there is is a body of theory underlying. Now, we will get into the details in a minute and we'll see how sort of solid or compelling that body of theory is. But there is a valid theory. I mean, there is the famous Drake Equation, for instance, about which we can we can talk in a minute, which purports to to give the basic outline of why is it worth in quantitative terms to do to engage in a study program.


Moreover, it's called all the other trappings of science. It's done by scientists. One thing you know is that by and by astronomers and physicists and some biologists, it's done using fairly sophisticated and very sophisticated scientific equipment. You know, these people use radio telescopes and highly sophisticated statistical analysis of the data. So, I mean, it's got all the trappings of science, except, as you pointed out, there is no empirical data at the moment.


But I was Clinton. Well, there is a claim, right? I mean, there is a hypothesis, not a claim.


There is a hypothesis is that there might be detectable life out there, right?


No, I think the hypothesis is stronger that the this is that there is detectable life out there, whether the hypothesis is correct or not.


It's one of those things that that's why they're looking. OK, so you can call it a hypothesis, but I don't to the best of my knowledge, none of the study proponents actually claim certainty that the hypothesis is true. They just think that it's worth investigating.


Right? Correct. But that but that goes also for pretty much anything else in science. I mean, if if you are a string theorist, which shows, you know, that's that's another one of those borderline areas that we've talked about in the past. Right. Right. If you're string theorists, you do claim that the universe has, whatever, 12 dimensions or thirteen dimensions.


If the theory is correct, I think. Oh, OK. So the question.


I think so the question you're asking about the scientific status of the search for extraterrestrial intelligence is whether the hypothesis is not testable. Is that testable?


OK, so so what was your conclusion in asking that?


Well, the hypothesis, I think, is testable because of course, if we, you know, suppose that tomorrow morning we wake up and we open up Nature or Science magazine or The New York Times or whatever, and we find out that the Sydney Institute has in fact, succeeded. But clearly, they thought that meant that would have meant that the hypothesis tested and and in fact, correct.


The problem is, what if we keep looking and we don't find anything for, you know, the studies going on since the 1950s on and off in different incarnations. So we're talking about 60 plus years already going. What if we go on for another century or another 200 years or another five hundred years without finding anything? Does that test empathises?


And I suspect the answer is no, because one could say, well, just because you haven't found anything doesn't mean that there's nothing out there in this case.


You know, skeptics often mistakenly, I think, claim that you cannot prove a negative, which is simply not true. For instance, you can easily prove the negative that I don't have a million dollars in my pockets. OK, you can search extensively through my pockets and make very, very obvious that the claim is, in fact true.


But in this case, since we're talking about the entire galaxy, it really would be very difficult to prove a negative.


Yeah, although I would.


That talking in terms of proving or not proving is probably a less useful way to think about things like I would I would frame the question in terms of becoming more or less confident in the existence of life. So if we looked for a long time and we and we felt that our methods of detection were were pretty strong and we didn't find any any evidence for 100 years, certainly that doesn't prove that there isn't alien life or intelligent alien life.


But but it is, you know, somewhat solid evidence against it. Well, that's that's actually debatable.


I mean, normally, I would agree with you, but because of the the presumably very low likelihood to do succeed to begin with, because we're talking about, after all, first of all, searching for, you know, the proverbial needle in the haystack where the haystack in this case is huge.


Right. Right. Also, we may be looking at the wrong moment in the wrong place. Right. So it's possible that, yes, there is a civilization or I don't know, on such and such and such and such a star, you know, a hundred light years away from us. And we just happen to be looking five seconds after they broadcast their signal. And that's too bad.


So it is one can make a reasonable argument that even after centuries of search, we actually have only scanned a tiny fraction of the total possibility, which means that you really don't have much of a leg to stand on, statistically speaking, because you haven't, you know, haven't taken into account enough of a sample size. Basically, the sample size is bound to be extremely small. It's both spatially and and temporally.


Yeah. So I was just then I was I was simply making the theoretical argument that that the lack of evidence, the lack of signals provides some evidence against alien life. But obviously the amount of evidence depends a lot on all those parameters of exactly how strong our detection methods actually are.


And you know what our prior estimate is of of the existence of intelligent alien life. I mean, it does.


I read a little bit about studies methods, and it it does seem pretty hopeless.


I mean, so, like I mean, first there's the problem that if you if you were beaming, if you were an alien civilization that was trying to be detected, which first of all, we don't know that they necessarily would be if you were trying to be detected, you would you would send a, you know, a beam out.


And the longer distance the beam travels, the more spread out it becomes and the harder it becomes to detect. So if we're talking about vast interstellar distances, then it would be very difficult to detect.


And then there's also the problem that not every kind of signal is actually detectable like so as the U.S. switched from analog to digital transmissions. Right. We became, you know, and much more invisible to other civilizations.


So if other civilizations went through the similar, you know, transition, technological transition as we did, as you know, we have good reason to think that they would, then they would become similarly much harder to detect.




Now there is I want to go back over to the statistical argument that we're having right a minute ago about, you know, we just said basically that even if, in fact, we don't find anything for 100 years or 200 years or something, because the space of possibilities or I should say the space time of possibilities is so big that doesn't that doesn't really necessarily tell you much now. I mean, it's interesting to reverse the that argument, which is what some city supporters do so well.


So a common argument in in the city community is that we already know that there is obviously at least one technologically advanced civilization capable of radio communication. That's us. Right.


And they they say, well, given that this is our only we have a sample size of one arm and they use what something called the principle of mediocrity to say that you are right to argue that, well, if there's no reason to think that we are, that we are unusual at all, statistically speaking.


So if in fact, we are representative of the space of possibilities, then it must be pretty, pretty frequent that there are technological civilizations capable of radio communication out there. Right.


That I have heard that argument made. And that is a bizarre argument. As has been pointed out by a philosopher a number of years ago, Andrei Kukla wrote an interesting article that we're going to link to and on the podcast site entitled Setit on the Prospects and Persued Worthiness of the Search for Extraterrestrial Intelligence.


And one of the things that he pointed out is that. The the principle of mediocrity is actually invalid, it's logically invalid, and perhaps the best way to understand that is that by the same principle, you could say something like, we know of the existence of teenagers who skateboard in New York City. Therefore, the existence of skating teenagers is a common feature of the universe. It's exactly the same argument, and it suffers from a very well known problem in logic, which is in some sense the reverse of Pascal's or it's right.


You actually took to the prom with Pascal's Wager and the existence of God. So let's let's remember, remind our listeners of that argument for a minute and then go back to city.


So Pascale's famously said that we don't know whether God exists or not, but he was making a probabilistic argument in favor of the fact that you should believe anyway, you should you make your bet in in in thinking that God actually does believe, because he said, after all, there are two possibilities.


Either God exists or doesn't exist.


And since the stakes are very potentially very high, because you got, you know, eternal damnation if you happen not to believe in God exists or eternal reward, if if you actually happen to believe in God and it does exist, then given those those given the rewards and punishments that are in stake and given that the probabilities are 50/50, it makes rational sense for Pa. to believe.


Now, there are several objections to Pascal's Wager, one of which, of course, would be what makes you think that God would be fooled by these probabilistic argument and wouldn't punish you for playing the odds instead of actually believing.


But anyway, other than that, I think number 25 on my list of problems from sorry, but the most fundamental, arguably the most fundamental problem with the whole argument is that, well, wait a minute, you're assuming that there's 50/50 chances. But in fact, which God are we talking about?


Because if there is a number of gods out there, possible gods out there, then of course, if there is a thousand gods, the probability is actually one in a thousand that you happen to pick the right one.


If there is 10000 gods, the probabilities are one in ten thousand, so on and so forth. And then you also have, of course, none of the above thing.


Now, would that show the possibility of the God who will damu to eternal hell if you believe in him?


Of course. Right. Yes. So once you take all the all these, if you actually do the the formal analysis of Pascal's Wager, it turns out that basically the problem arises from this from from the following situation, that he has a case scenario, a in case, you know, you'll be except a case scenario B, the existence of God is subdivided in itself in a bunch of other scenarios, B, one, B, to be an up to B, infinity.


And so that you cannot. And by the logic of the argument, you should say that they're all equally probable and the argument quickly degenerates into nonsense. Now, the thing with Setti, the argument, assuming that we are a representative sample the universe, just because we know that we exist falling into a similar has a similar problem.


That is, you can make any number of statements about anything that we know about Earth and by the same exact reasoning, argue that those are in fact, those situations are in fact characteristic or statistically representative of the entire galaxy, which they're clearly not. I mean, I doubt that any city supporter, for instance, would seriously take the proposition that a skating teenagers, skateboarding teenagers are a common feature of the galaxy. But the thinking is exactly the same.


You cannot you simply cannot say how representative the Earth and our civilization is precisely because you have a sample size of one. The majority simply does not. It's inconsistent, incoherent from a logical perspective. So you can't argue on that ground all that.


The that observation tells you is that, yes, there is at least one civilization out there so that it is possible to have technological civilizations in the case.


But we knew that to begin with. And that wasn't that's not a particularly profound discovery. It really tells you pretty much nothing.


But as the author says, Kukali says, some point says the only logical, rational boundary bounds that you can put on the chances that there is another civilization out there is between zero and one in between. Not not at all. And 100 percent certainty. In other words, you're not saying anything that you had no grounds, no epistemic grounds for actually making any prediction whatsoever because you have a sample size and one, I think you can bounded it a little bit more than wondered.


Exactly. Well, so first, I should say I like your argument.


It's slightly different from the argument that I would have used against the mediocrity principle, which is that the the argument that, you know, based on our sample size of one, we you know, we think that it's actually not that unlikely that life would arise.


That reasoning suffers from basically the anthropic bias that no matter.


So what we're interested in. Guestimating is what is the chances of life developing per planet, essentially? And we look at the information we have, which is that, well, here's one planet and life grows on it.


So the problem is that no matter how small the likelihood is per planet of life developing.


If it develops on even one single planet, intelligent life anyway, then the intelligent life on that planet is going to look at their history and say, hey, well, intelligent life evolved here.


So then it must not be that unlikely.


And and so the problem is that as long as it's greater than zero, no matter how tiny it is, it could be one in, you know, a trillion, trillion, trillion chance of life.


Developing the planet where it develops will always think erroneously that it's more likely that that's what it was.


So that's actually really what you're saying is actually read to another point that Kukla makes in his article, which is that it is certainly the case that you can make an argument that if if the universe were, in fact infinite, that there is that there is an infinite number of possibilities out there, an infinite amount of time out there, then an event with even infinite, you know, vanishingly small probabilities bound to happen eventually.


But the problem is that, first of all, we actually have.


So then there are skateboarding teenagers somewhere out there, a number of skateboarding teenagers. Precisely. Except, of course, that we have no reason to believe that the universe is, in fact, infinite according to into multiverse.


That was your premise for now. So go going. Right.


But the other the other thing is Kukla makes the point that actually there is nothing that prohibits that precludes the possibility that, say, the laws of physics are such that there are unique events in any particular universe and we could be that unique events event.


So it's not it's not true that assuming that you have a sample size of one, it is not true that you can make the leap from saying, oh, well, there is at least one. So there must be at least a small probability that there is another one. It could very well be the case that there was only one of those events.


For instance, you know, take the origin of the universe itself. After all, the Big Bang did happen once, as far as we can tell. So that event is not just rare. It really is unique.


Hmm, that's interesting. I think the the argument that if you have an infinite number of opportunities for something to happen, then it will happen an infinite number of times.


I think I guess that's based on the assumption, which is sort of the theoretical assumption that for every conceivable event, it has some probability of happening in any given situation and any given opportunity.


And so if you envision this sort of fundamental probability P and you, you know, have an infinite number of of trials, then no matter how tiny is it will happen an infinite number of times. That's how the reasoning goes. But I guess if you abandon the idea that there's that every everything has some fundamental probability of happening and a given opportunity, then then yeah, you could sort of somehow arrange the hypothetical universe such that it only happens once.


Right. The final thing that I think about is this whole idea is we should get more a little more into the theory behind city. But this particular argument there that if even if something is a small probability of happening, given an infinite universe, it is bound to happen over and over. This section goes back to Lucretius to the right of Matura.


So this is a 20 year old what to look for and say, look, you said something along the lines of, you know, given that the if the universe is in fact infinite, any event is bound to happen over and over, no matter how unlikely the event is. And he started that argument from a completely mechanistic perspective.


Lucretius was, you know, a follower of the Greek optimists. So he was a complete materialist. And, you know, the right I'm not sure it's a great book. It's it's a it's a poem basically that that explains the mechanistic view of the ancient alchemists. And it's beautifully written. It's it was a highly, you know, enormously influential book in ancient literature, arguably into the Renaissance, actually. But it does start with this assumption that there is, in fact, an infinite universe out there.


And that assumption seems to be questioned by modern physics. So we don't actually think anymore that the universe is infinite. Again, unless you're talking about we're talking about multiverse, which is a whole different, different story.


Right. But that does complicate things. I actually like the idea that the universe is infinite just because of some of the conceptual paradoxes and conundrums that generates.


So one of my favorites, this is off topic, but just briefly, one of my favorites is the difficulty that it poses for utilitarian ethics.


So if you if you take the the premise, sort of one of the basic premises of some common forms of utilitarianism that you're trying to increase the average utility in the world or in the universe, then no matter how much good you do, you're doing a finite amount of good.


Right. And if you divide a finite amount of good by an infinite number of or an infinite amount of utility in the universe, you know, infinite number of beings, then you've done exactly zero good no matter no matter how much good you do.


Yeah, there's a finite number divided by infinity.


That's an argument against cosmic utilitarianism in an infinite universe.


Anyway, we're a little off track, but wait, let me finish the thought I started earlier, so I had argued against the idea that we can take our existence of intelligent life here as evidence that it's likely to arise on any given planet in the universe.


But I did say that I thought you are the existence of intelligent life. Here was evidence that we could bound the probability. Right, slightly more than zero to 100. And that's that if the probability of life arising on a planet were significantly less than one divided by 100 billion tons, 100 billion, which is no.


Right. Right. Right. So we represent one occurrence of life.


We know that there's at least one occurrence of intelligent life divided by all of the number of opportunities for intelligent life to arise. And so there are, what, 100 billion planets about our galaxy?


Well, we don't know. There is the buzz. There is about 100 billion stars in our galaxy. We don't know how many of those actually have planets.


OK, but let's be sure that 100 billion times a hundred billion sorry, one divided by that, we can take that as like the lower sort of a rough lower bound for the probability of life arising on a planet because of the probability were much, much lower than that.


Then it would be really unlikely for even one occurrence of life to arise. And we know that one did.


Correct, except that that does make one big assumption that some some writers, like the one that I was mentioning before, you know, Kukali actually rejects or at least question, which is that you can actually that it actually makes sense to attach a probability to a unique event. Yeah, I know.


That's that's tricky. I actually don't quite know how to think.


So if it if if we're talking about that, that would get us into the philosophy of probability, which is probably beyond the what we want to talk about today. But it is an interesting question because, you know, it does depend on what you mean by probability and how do you actually estimate the probability or the likelihood of something. But I want to go back to the basics for a minute.


So let's start with the the basic theory behind the Saudi effort, which, of course, is the famous Drake equation.


We just cannot talk about setted without talking about the Drake Equation, which is named after Frank Drake, was one of the originators of the of the whole city, and they were back in the 50s.


Now, the equation is well known and you'll find that easily anywhere in a number of publications. There is, as you mentioned in one of the chapters of my nonsense until stories and a detailed explanation of the equation. But essentially, the equation is a way to frame the problem conceptually and and figure out if there is a way, at least to get a ballpark idea of it for estimating. And that is the number of technologically advanced civilizations capable of radio communication.


And the equation depends on a number of parameters. And I very briefly go through them because we need to have some idea of what it is that that the city effort is being based on.


So the parameters are are the rate of formations of stars in the galaxy. Mm hmm. F.P. the fraction of stars that have planets and the number of planets capable of supporting life that are orbiting those stars that have and they do have planetary systems. F.L. The fraction of planets capable of supporting life, where life in fact does evolve. F.I. The fraction of the ladder that develops intelligent life at sea, the fraction of civilizations capable of producing interstellar signals.


And then l the length of the time of time during which a technological legitimisation exists that is capable of sending out these signals.


Now you can actually have our listeners can have fun plugging in their own numbers into the Drake equation. Both the Saudi Institute, I think, and NASA have their own calculators online. You can put in there, put your numbers and see what comes out as as. And now the most recent estimate that I've looked at, it's not actually that recent that goes back to a couple of years ago. But anyway, the the recent estimate that I have from NASA about and the number of civilizations in the galaxy is only a surprisingly small two point three.


Two point three, yes, on average, of course, since there are no fractional civilizations, that means, you know, about two. Now we have one.


So according to the best estimate and Naza published a couple of years ago, there's probably just one out other civilization out there in the entire galaxy at this moment capable of communicating, which is not exactly encouraging.


But the more important thing is, in fact, these numbers don't make much sense, because if you think about it, some of these parameters, we know either how to estimate them or we have some ideas about them.


Right. For instance, the rate of formation of stars in the galaxy is actually fairly well known. You know, astronomers have figured out for the Milky Way and similar galaxies what that rate is, the fraction of stars that have planets.


Until a few years ago, we have no idea of how many there were.


But now in the last several years, we discovered a few hundred extrasolar planets. Now, true, there are all nearby because otherwise people would be able to see them or detect them.


So they really represent a sample of the planets only in our immediate neighbourhood, in the galaxy. It's not that easy to extrapolate to the entire galaxy because the stability of planetary orbits depends on the density of stars and a number of other situations. And since our arm of the galaxy, our our area of the galaxy is actually pretty sparsely populated by stars. But if you move much closer to the center, one can argue, for instance, that the star density is simply too high to allow a stable planetary systems.


But let's see. But at any rate, we have an idea at least of what that number is after that.


Unfortunately, you know, your guess is as just as good as anybody else's guess because the number of planets capable of supporting life orbiting those stars, well, we don't know.


Again, in this point, we only have our own example. It is true that as far as the planets that have been discovered, extrasolar planets have been discovered recently. People can guess based on their mass and their distance from the stars, but that becomes a pretty big guess. And if you move toward the right of the Drake equation, then things become even more.


If it's, you know, the fraction of of the those planets that develop intelligent life, what we have no idea how to estimate that. We don't know how what's the probability of intelligent life to actually emerge.


And we certainly don't know what is the fraction of that that number that eventually developed civilizations capable of interstellar communications.


Again, we have no example of our own and we don't even have a single example to estimate the length of a technological civilization because we know only of one technological civilization and it still exists. Fortunately, we haven't gone extinct, so we don't know how much on average technological civilization exists. Even if you were to take the principle of mediocrity as valid, which as we said earlier, is not so.


In other words, the last three or four parameters of the equation, you can pretty much put in there whatever numbers you want, which means that the total estimate is, let's say, not exactly reliable.


Yeah, it seems like there's enough uncertainty about each of the many components of the Drake equation that.


If you if you were to try to come up with an overall range of uncertainty for the whole estimate, it would multiply very quickly with each additional high uncertainty component that you add to the equation that seems right.


You know, like pretty unstable. Like if you were to to change any one or two of the parameters of your estimate of the parameters slightly, you would get a very, very different estimate overall. So, yeah, exactly.


So the theory is really not bounded at all. I mean, the Drake Equation was a very good effort, especially because it was produced really very early on. It was sort of a way to start thinking about these things quantitatively. But one of the things that actually is not doesn't look very good for the city project at the moment. And I'm talking about from a theoretical perspective, not from obviously from an empirical perspective, they have not discovered anything yet.


But that could change that could change tomorrow for them and in fact, could change before this episode gets broadcast, in which case we'll have to do an appendix to it.


But from a theoretical perspective, one of the things that doesn't look very good for Sandy is that the major piece of theory behind the entire effort was produced in the 1950s and it hasn't been improved much, in fact, at all since.


Now, the philosopher of science, Imlach Arthur, who was a student of Popper, famously said that some research programs in science are degenerate, meaning that they don't lead anywhere, they don't produce any more theoretical advancements or empirical advancements. From that perspective, the city research program is in fact the generate. Now, as Lakatos pointed out, even at the general research program can suddenly pick up if something new happens. But not much has happened.


Now, when I put that in in the book, when I when I pointed out that the theoretical basis of FCD were not particularly exciting and certainly have not seen any recent developments, I was actually told by a couple of people to look at papers that are that recently suggest that the rights that had been flat, theoretical developments in Syria. And I'm looking at one of them in particular, which again, will link from the website. This is a paper that came out a few years ago in new astronomy by Mullein Milen Kick of Kirkuk and Robert Bradberry.


It's entitled Galactic Gridiron's Post Biological Evolution and the Apparent Failure of Safety. Now, right at the beginning on that paper, the others list a series of advancements for Setit, either empirical or theoretical advancements. Forseti And I'll read you very briefly what these things are, these advancements consist of. And I think one can argue that none of these are actually advancements of Saidy, per say.


They are advancements in other areas of either biology or astronomy that have something to do with their pertinent to. But not. But that's not quite the same thing. So, for instance, the first advancement, obviously, that they cite is the discovery of extrasolar planets.


Now, that is, in fact, directly an empirical advancement that does sort of help out the city project because that is one of the parameters and Drake equation.


But the other ones are, you know, an improved understanding of the details of chemical and dynamical structure of the Milky Way and its galactic habitable zone. OK, well, that's really advancement in, you know, structure of astrophysics more than actually anything to do directly with city. They claim that we can because of that and understanding better understanding of chemical and dynamical structure in the Milky Way, we can make better speculations about the galactic habitable zone, habitable zone.


But I think that those are still speculations. The third point is a confirmation of the rapid origination of life on Earth. OK, but that's really life bound biology. This is this is about the origin of life on Earth. We don't know whether those things apply and in other places or not.


Well, but it might bear on how likely we think life is to rise. Another planet, perhaps.


But remember that, yes, the optimists would say so. But remember that, again, we're talking about, as far as we know, a unique event. And we just were discussing, you know, you can't really say what the probability of a unique event is until you have a second, at least the second event by comparison.


Yeah, but so, for example, that the greater the number of independent things that would have to be true in order for life to develop, the less likely we should think life is to develop another planet.


So it should adjust our estimates.


Yeah, but we don't actually know how life originated on Earth. No, we don't. But I'm just saying that investigating that, investigating the conditions that would have been necessary for that to happen is relevant to Saturday's mission.


Yeah, I would say it's relevant only tangentially. And the bad news for Saidi's that we haven't really made any progress in that. I mean, yes, we know that life originated pretty quickly on Earth after the origin of the planet itself. But we really don't have much of a clue in terms of what actually happened, actually.


Interestingly, the the argument that life originated pretty quickly after the after of the origin of our planet is also subject to the anthropic bias.


Because it's conditioned on the fact that we are an intelligent species existing at the point in our planet's history that we are currently.


So even if it were really unlikely for life to originate this early in a planet's history.


Still, if it happened at least once, the intelligent creatures at this point in time would look back and say, oh, well, it happened so early, so it must not be that unlikely.


The entropic bias is really difficult to avoid in all these discussions anyway. So continuing the Kekovich and Bradberry list, then we get into discovery of extremophiles bacterial forms. So these are these are, you know, bacteria that live under very unusual conditions on earth.


Right. Which is relevant because it indicates that it would be possible for microbes to spread from planet to planet on meteoroids or asteroids, perhaps.


But again, we're talking really high, highly speculative things. And this is really more, again, an advanced advancement of of terrestrial biology. We do not know. We it's very difficult to extrapolate and you know, to what extent these kinds of forms of life, for instance, could exist in a completely different planet.


For one for one thing, even the extremophiles on Earth actually live, of course, by definition in the rest of environments, unusual stress environments, but nonetheless terrestrial environments.


That doesn't really tell you necessarily unless you actually know something about the biochemical sorry, the physical chemistry of extrasolar planets, which we don't, then it's hard to imagine what exactly that's going to tell you other than saying, yeah, it's possible that there is a variety of things of the more variety of things out there than we might we thought.


Originally, I thought the relevance of that finding was that it makes it much it makes it more likely that there's life developing on on many more planets than we would have thought otherwise. Because if it's possible for life to travel from planet to planet as the existence of these extremophiles now suggests, then life would only have to originate on a few planets and then be carried by meteorites and asteroids and spread to many more. So you wouldn't need nearly as many independent generations of life yet to get a better life.


Yes, but I'm going to disagree that the discovery of the extremophiles actually make it more likely or suggests, you know, any way that these forms can travel from plant to plant with. What it does suggest is that you don't need that. You can have life on earth living in a broader range of habitats than we previously thought. You know, some of these things, for instance, live in very high temperature or high pressure environments. Right. But none of these, as far as we know, it lives in anything or it can survive in anything like space.


But I thought that had actually been investigated. Like, have you heard of the water bear? It's this water bear. Walterboro.


Yeah, it's my favorite animal. So if you can call it an animal, it's this tiny microorganism that can survive at temperatures near absolute zero and it can go without nutrition for years on end and it can survive at incredibly high temperatures.


So in theory, an organism like the water bear could pass through.


I mean, it could survive the extreme cold of outer space that could last for years on an asteroid or meteorite, and it could survive the entry into the atmosphere of a planet which would be extremely hot.


That's it's like a proof of concept. I'm going to I'm going to be pretty skeptical about the water bear. It's really cool. I will. But the thing is, again, it's one thing to show that these things can resist very unusual conditions is another thing that to actually make a serious case, that they can travel for long periods of time and do things like, you know, surviving reentry, for instance, in an atmosphere which not even meteorites often survive, let alone bacteria.


Anyway, there is some evidence, again, that there is some you know, we certainly have improved our understanding, as these others say, of the molecular biology and biochemistry, these things. But then they go on and say, you know, for instance, they count as a success or as bearing on getting a better understanding of the molecular biology of life in general and the hiden confidence in the theories of naturalistic origin of life.


Well, I don't think any any scientist ever doubted the naturalistic origin of life. So I don't see how that could possibly help the city endeavor. Sure.


Also, the exponential growth that the technological civilization on Earth is, as they say, particular referring to Moore's Law and of the speed of advancement of technology.


Well, you know, that that only applies to very, very short period of time, even within the history of our civilization. So I'm not sure, again, how much you want to extrapolate on that. And then, moreover, improved understanding of the feasibility of interstellar travel. I really don't think that we have much of an understanding of interstellar travel. There's a lot of speculation, but certainly understanding.


I think it's a little bit of a stretch.


And finally, theoretical grounding in various astro engineering and macro engineering projects. Now, that is entirely speculative. We've never done a master engineering project. We just have people talking about it. Now, if this is the best that city theorists can do, it's interesting, but it's definitely highly speculative.


You know, I strongly invite our listeners to actually check out the Kekovich and bribery paper. You will see that by the end of it, it begins to look like a science fiction, you know, speculative sort of effort.


They may even be right on what they're saying.


All I'm saying is it doesn't rise much to the level of, you know, well grounded scientific theory.


Before we wrap up, I'd like to mention one other interesting philosophical argument that's relevant to the search for extraterrestrial life so much more. Have you heard of the Great Filter argument? Go ahead, give us the argument is called the Great Filter argument, the term Great Filter was originally coined by Robin Hanson. And I'm going to link to this paper that outlines it in a nice, clear way. This was published in MIT's Technology Review in 2008 by Nick Bostrom.


And the title is Where Are They? Why I Hope The Search for Extraterrestrial Life Finds Nothing. So.


So here's the argument roughly. So there are about 100 billion stars in our galaxy, about 100 billion galaxies in the observable universe. Many of these stars have planets, and we've every reason to believe that there are a vast number of Earth like planets in the universe.


And then there's other evidence of the possibility of of conditions that are habitable to life.


So, you know, the subsurface ocean on Europa, one of Jupiter's moons, evidence that Mars once had water or is likely to have once had water and then the extremophiles, which I think is, you know, telling evidence Nasima doesn't.


But anyway, so despite all the many, many opportunities for life to develop, after decades of searching, we've never encountered any traces of intelligent civilizations and the rest of the universe.


So from those two facts, we can conclude that there exists a great filter, which is essentially like a probability barrier, some necessary and very improbable or very difficult to satisfy condition for the development of civilizations that could send out interstellar signals.


So the argument that Nick Bostrom and other people like Robin Hanson have made is that this great filter could it could either exist in our evolutionary past.


So the great filter could be something like it's very, very improbable for life to even occur at all, or it could be something like it's very, very improbable for intelligent life to develop. Like maybe there are many planets that have some kind of microbial life. But the number of conditions that would have to all co occur in order for something like humans to develop is incredibly rare. And so so that would explain the paucity of interstellar civilizations or the great filter could exist in our future.


It could be that it's actually not that uncommon for intelligent civilizations to develop.


But when they do, they almost always self-destruct at some point, you know, due to war, you know, or or epidemiological disasters or they they run out of resources because they consume at such a rapacious rate.


So so essentially, what what Nick Bostrom is saying is if we find evidence of life in our galaxy, then that's suggesting that the great filter probably doesn't lie in our past because finding life in our galaxy would indicate that it's not actually that improbable for life to develop.


So that makes it more likely that the filter exists in our future, that it's actually much more uncommon for intelligent life to actually be able to to sustain itself without self destructing for the period of time that it would take for them to be able to develop the technology to send out interstellar signals.


Well, it sounds to me like this is the ones that you just mentioned are some of the answers that have been proposed over over the years in response to this famous Fermi paradox, which is another one of those things you just cannot talk about started without me, right?


No, it is. It is it was a response to the Fermi paradox. Do you want to explain? Yeah. So Fermi's paradox apparently came out in its name after Enrico Fermi, the physicist who contribute to the development of the atomic bomb.


And apparently what happened was the family was having a conversation back in the early 50s with some of his colleagues who were all excited about these new ideas about safety.


And Freeman did some back of the envelope or of the napping napkin calculation. They were having lunch.


And then he says, well, if this is the case, then where is everybody?


And what he meant by that was that even under very pessimistic assumptions about how quickly a civilization would spread throughout the galaxy because of the very, very old age of the galaxy and and many of the stars in the galaxy, we already should have been seeing plenty of evidence about the civilizations.


The fact that we haven't seen might indicate that it doesn't exist. Now, the first time I heard the argument, it sounded a little bizarre.


There is this analogy, however, that on the on the City Institute, on the explanation for the for the Fermi paradox, there's this interesting analogy that I think make the make makes for me point a little more clear. It says, you know, I'm reading directly from the City Institute website at this point.


It's like having a heated discussion about whether Spanish ships in the 16th century could have come here along at two knots or 20 knots. Either way, they could have speedily colonized the Americas. In other words, it doesn't really matter whether you assume that these technological civilizations going on, that this particular fraction of the speed of light or another, it doesn't matter given the amount of time that is available.


They should already be in here now. Some of the parties that you mentioned are, in fact, some of the possible answers to Fermi's paradox.


So if one has to speculate about how to answer the Fermi's paradox, assuming that one does take the Fermi's paradox seriously, which I'm still not convinced, my favorite part is the so-called Tsou hypothesis and which basically says that, oh, yes, there are plenty of other civilizations out there and they're just looking onto us as if we were sort of a, you know, curious animals inside a zoo. And that's why we don't see them for the same reason that a lot of animals in the zoo don't see the zookeepers.


I mean, once you start that way, unfortunately, we run into the same problem, sort of the opposite, the opposite version of the same problem from that we started talking about in the beginning and the mediocrity principle of the one based on the principle that is there really is no sensible way of making sense of, you know, speculations about, well, this is more probable than that or these answers more likely than that.


Again, I think that the the sensible thing to say is the same conclusion to arrive at the same conclusion, at the same conclusion. And the Kukla arrives in that paper that I mentioned earlier on, which is really for one week.


All we can say is that the bound of of our estimates for the existence of extraterrestrial civilizations is between zero and one, which essentially is another way to say it's a fancy way to say, you know, we had no frickin idea what's going on there.


Now, again, I hope that we're going to be proven wrong by the time this podcast comes out. You know, like I love to wake up tomorrow morning and see in The New York Times and front page that the city institutions actually succeeded in what they're trying to do. And then we'll see.


But there is a problem in there because in fact, this came out very recently in an article in The New York Times, as it turns out, by Gary Gutman, who is a philosopher, and he said the article is entitled Will the Aliens Be Nice? Don't bet on it.


And the idea was that, look, these all these enthusiasm about the positive outcome of a of the discovery of Western civilization, you know? Oh, well, it will have profound implications for us from philosophical and religiously, perhaps will cure diseases, will end war and all that.


And of course, the point is that you keep forgetting what actually happened in the history of humanity when one civilization discovered the other day usually killed them.


And if there is, in fact, a reasonable chance of that happening, it might not be a good idea to actually look too hard for extraterrestrial civilizations.


Right. So that actually I mean, that sort of thing that's brought up by some critics of Saudi, not the kind of critics who say this is futile. It's a stupid idea. It's not ever going to work. The critics who say this is a terrible idea because it's dangerous work.


I mean, it's not a completely ridiculous argument. And it is also I think it's a legitimate criticism that's been made by many people, including, rather famously, David Brin, who's a famous science fiction author, that the book, even Stephen Hawking, recently made that.


Oh, yes, Stephen Hawking also has made that argument.


But I remember David Byrne saying a while back that it's crazy that something an endeavor like this that has such huge implications for the future of humanity is being was made just by the small, insular group of people without really ever consultation of of the rest of us.


Anyway, we're way over time.


So let's wrap up the section of the podcast and move on to the rationally speaking, PEX. Welcome back. Every episode, Julie and I pick a couple of our favorite books, movies, websites or whatever tickles our rational fancy. Let's start as usual with Julia Spik.


Thanks, Massimo. My pick is a website. It's called Ask a Mathematician. Ask a Physicist so I could potentially be accused of nepotism because this website is run by two of my very dear friends.


But it's it's also I will not raise that accusation.


Well, I feel I feel legitimized in in bringing it up as a pick now because they've sort of hit the big time. They were at the top of Reddit Science and Technology page pretty recently. They've been getting a lot of traffic. So basically the story behind this website, it was born several years ago at Burning Man when my two friends, a mathematician and a physicist, set up a tent and hung a sign saying, ask a mathematician, ask a physicist, and invited people to come and ask them questions about math and physics.


So they got due to the population at Burning Man, which ranges from the giants of the tech and research world to very, very stoned people wondering.


I heard that they got they got a whole range of questions from like questions at the cutting edge of quantum physics to well, for example, there was one guy who wandered in and just asked why?


And they're like, why? What? He said, no, just why.


It's a pretty broad question. Yeah. So they try to answer everything, including questions like how do I find the love of my life and what is the meaning of life? And they try to answer them using math and physics. Good luck.


They're they're very I mean, most of the questions on the website are actually really interesting math and physics questions.


And they're they're answered in a very entertaining way.


So, for example, there's the question, how do you talk about the size of infinity?


How can one infinity be bigger than another?


There's the question, is it possible to destroy a black hole if we meet aliens? Will they have the same math and physics that we do? And this was a question submitted by me, and it was also one of the most popular posts. Can you do the double slit experiment with a cat cannon? Can you shoot a cat at a giant?


And this is well, you'll have to read it to find out. I warn you, it's full of really terrible puns about cats.


So, yeah, I don't mind. I'm I'm a dog person. OK, my back, on the other hand, is a edit, a book called Dr Who and Philosophy Bigger on the Inside, edited by Courtney Lewis. And Mitka, this is one of these, you know, ongoing series. There are two or three publishers who for a number of years now have been putting out books about philosophy and pop culture. And I am a big fan of Doctor Who, the science fiction British television show that has actually is the longest running science fiction television show ever, although it hasn't been continuously running.


But it started in 1963, a year before I was born. So it's almost half a century old. It is going now through a new incarnation since they rebooted the series in 2005. And the book, of course, uses the the many adventures of Doctor Who, who is a time traveler and alien time traveler. And and of course, they used the various adventures to introduce the public to a variety of philosophical issues from the obvious one time and time traveling to questions of identity.


You know, who is this doctor who? Because this guy obviously challenges all sorts of theories of ident personal identity that one can possibly have in terms of, you know, is your personal identity determined by your memories, by you?


Have there been like six doctors now? They've been 11 that this is 11 doctors. So clearly there is an issue with personal identity there. And then there is a lot of discussions about ethics because, of course, the doctor gets into all sorts of interesting situations, including in two occasions.


It causes a genocide for apparently good reasons. And so, you know, that raises the question of is it ever a good idea to cause genocide?


Anyway, it's very well written book. There is a little bit of redundancy in the chapters on personal identity. The editors, I think, could have done a slightly better job in that area. But it is fascinating. And if you are a doctor who fan, this is definitely a must read. And if you're not, you should be.


So this is also I, I hope somewhere in there there's a metaphysical discussion about whether it's possible for the phone booth to be bigger on the inside than on the outside. Absolutely there is.


This concludes another episode of rationally speaking. Join us next time for more explorations on the borderlands between reason and nonsense.


The rationally speaking podcast is presented by New York City skeptics for program notes, links, and to get involved in an online conversation about this and other episodes, please visit rationally speaking podcast Dog. This podcast is produced by Benny Pollack and recorded in the heart of Greenwich Village, New York. Our theme, Truth by Todd Rundgren, is used by permission. Thank you for listening.