John Donvan

Hi, everybody, and welcome to Agree to Disagree, from Intelligence Squared. I’m John Donvan. And for the debate we’re about to have, we are going to look up. We’re gonna look up and ponder the possibility that up above us, up and out beyond the clouds and the moon and the sun and our solar system, that there is other life out there. And, that it is intelligent life. And what we’re going to debate is whether we should be investing energy and money and time in trying to discover that life. Which, in fact, is something that’s already happening. The search is on. And in the course of this program, we hope to learn the odds that there are extraterrestrials with intelligence out there. And we hope to learn the pros and the cons of looking for them. And the pros and cons of actually finding them.

Here’s how we are framing the question. Quite simply, should we search for life in space? We are going to hear two answers to that question, a “yes” and a “no”, curtesy of two experts. Jill Cornell Tarter is an astronomer best known for her work on the search for extraterrestrial intelligence, and a co-founder and former director of the Center for SETI Research. Paul M. Sutter is an astrophysicist at the Flatiron institute. Jill and Paul, thanks so much for joining us on Agree to Disagree.

Jill Tarter

Wow, thanks so much for having us and for this topic.

Paul Sutter

And I’m very much looking forward to this discussion.

John Donvan

Okay, so, Jill Tarter, you go first on the question. Should we search for life in space? Are you are “yes” or are you a “no”?

Jill Tarter

Absolutely yes.

John Donvan

Okay. Paul Sutter, that means you’re the “no”, but make it clear to us so we can make it official on the question of, should we search for life in space? Are you a “yes” or a “no”?

Paul Sutter

I am a “no” because I believe it is not a very fruitful question to ask.

John Donvan

All right. An interesting starting point. So, Jill, you got off to a fast start in telling us about your enthusiasm for the… for the search for intelligent life in space. But take a few minutes now and tell us why you’re so passionate about the search.

Jill Tarter

I think at this particular time in our history on this planet, it’s very, very important to, uh, encourage people to have a cosmic perspective. And I think there’s nothing that does that more than thinking about life beyond Earth and intelligent life beyond Earth. And, why is a cosmic perspective, um, a necessity? It’s because we have all of these challenges on this planet, with respect to having a long future, um, food insecurity, water insecurity, all kinds of political and, um, you know, even war, to, like, uh, differences. And we’re not gonna be able to solve these challenges as nation states. We’re going to have to have a global cooperative consensus about how to deal with these challenges. And I think that when we talk about life beyond Earth, particularly intelligent life, we’re in fact holding up a mirror to all the people in the conversation. And that mirror shows us not that we are all different, but that we are really all fundamentally Earthlings. And we need this cosmic perspective to make us act like Earthlings to cooperate in ways that we have traditionally not done.

John Donvan

All right. A very interesting case made about perspective. Cosmic perspective being involved a benefit of searching for life out there beyond the stars. Paul Sutter, you are a “no” on the question of whether we should be searching for intelligent life in space. Why are you a “no”?

Paul Sutter

I’d like to start off by saying I am a cosmologist. And I wholeheartedly agree with Dr. Tarter’s, uh, statement that we should have a cosmic perspective, that we should look bigger than the Earth, we should look, uh, through the lens that we are one tiny little planet clinging to the life a-… you know, in the habitable zone of a star. Uh, that, we should come together to solve our problems that face us as, as a global community, uh, problems like climate change. And, that we need to cooperate. We need to invest in a long-term future. And, and so, that was very beautifully put and I completely agree.

I don’t know, however, if the search for extraterrestrial life, uh, speaks directly or in isolation to those problems. Uh, there are other questions we can ask that offer us that cosmic perspective. We can investigate the origins of the solar system. We can investigate and search for non-intelligent life. We can study the, the Big Bang and the ultimate fate of the universe and how stars are born and cycle through generation after generation. There are so many beautiful, wonderful, powerful questions that confront us as curious, inquisitive humans that we are. And that, on balance, when we look at all the questions we can possibly investigate, and all the possible lines of inquiry, and all the things that we can possibly be curious about, the search for extraterrestrial intelligence is one of those questions. It certainly is. And I would never be one too, uh, put down or diminish someone else’s curiosity.

Uh, but we do not have unlimited resources, unlimited time, unlimited brain power to investigate these questions. And so, we have to take the question of, “Are we alone in the universe?” which is a very powerful, moving question, and put it in context with the other questions that are equally as powerful and equally as moving. And aside, with our precious resources that we have available in astronomy, how much s- should we devote to this question?

John Donvan

So, so let me just stay with you for a moment longer, Paul. If I understand what you’re saying, the, the harm, if there’s any harm that might be caused by in continuing the search for intelligent life, would be a misallocation of resources, relative to other things that could be done with those resources. Is that the crux of your argument?

Paul Sutter

Uh, yeah, that’s the crux of one of my arguments, is there’s an opportunity cost to searching for extraterrestrial life. Uh, there’s another argument that I- I’ll probably present later, which focuses on the public harm due to false alarms of when we find signals or apparent evidence of extraterrestrial life and we go out in the press and make a big deal about it. And it turns out it is not a signal, it is not a sign of intelligent life. Ultimately, that harms the relationship between scientists and the public.

John Donvan

All right, Jill, let me bring it back to you. And w- what is the… what does the search involve now? What sorts of resources and… You’ve been involved in it for so long. Um, and, and for folks who don’t know, I mean, you are a giant in this field, and, um, everybody who saw the film Contact back in the late ’90s about Jodie Foster, uh, being involved in the search intelligent life knows that you were a consultant on that film. Uh, you are highly, highly respected in this field. And obviously you’re passionate about it. So, there’s probably nobody better equipped than you to tell us, how has that search been going? How is it financed? And then, I’d like you to get to the question of the use of resources.

Jill Tarter

The resources that are being spent are minimal. Uh, they are within the means of some of our most, um, wealthy individuals, and that’s how it’s being funded this year, and, uh, for the past few decades. Um, we’re talking about maybe spending $10 million a year. I think it’s more like… I kinda have the feeling $10 billion a week to, to support something like the James Webb Space Telescope, which will show us all of these wonders that, that Paul has been talking about being interested in finding. But what, what the wonderful telescopes that are on the books, uh, or on, on the sky right now, um, will tell us about is astrophysical phenomena. It won’t tell us about whether there’s any engineered phenomena out there. So, we can make use of archival data from the astronomers’ resources to try and look at a new way at that data. Uh, to see if we can find some patterns that, that we don’t think nature can produce. But in general, we have to build our own tools because we’re looking for things that the astronomers are not looking for.

And so, $10 million a year seems, to me, like not an unreasonable investment. And if you asked me, “Well, what would I do with a hundred million dollars or a billion dollars a year?” I actually… I actually can’t answer that question. Because our ability to search is limited by the physics that we currently understand. I mean, maybe we should be looking for Zeta rays. Uh, I don’t know what a Zeta ray is. We haven’t yet discovered it. We need to stick around long enough to get smart enough to figure out that that’s a viable method of transferring information over the vast distances between the stars. So, this is a modest program. I think it should be ci-… be, be, uh… remain modest. Because we can’t promise results, right? We don’t know the answer to the question. We may, in fact, be the only intelligent beings in the universe, in spite of the very large numbers that might argue otherwise.

There’s, um, there’s a paper in the past few years written by the folks from the Institute for the Future, over in, um, in the UK, uh, which looks at the various factors of the Drake equation. Which, really isn’t a q-… an equation. It’s just a way of organizing our ignorance. But there is a factor that says what fraction of all the potentially habitable planets actually develop life and then go on to, um, another fraction that says, and of that set, which go on to develop technology? But that F sub L fraction that developed life [inaudible

]… When you do a literature study, you come up with… or, the, the folks in the UK did, uh, come up with the fact that in the literature, there a 120 orders of magnitude. Not just a factor of 120. But 120 factors of 10, um, estimates of what that fraction might be. So, it’s a huge unknown. Lots of people working on it. Uh, and I think that, uh, this really drives our, uh, association with the cosmos.

Did what happened here happen somewhere else? Or did something else somewhere else happen to produce a result that is, uh, functionally equivalent and has the ability to communicate over large distances? So, I, I really do think that we, at, at base of all of this, is wondering how we fit into the cosmos. We like to study and we’re interested in nothing more than we’re interested in ourselves. And we’d like to know whether we are singular or normal, above average, below average. How do we fit into this cosmos?

John Donvan

More from Intelligence Squared US when we return.

Welcome back to Intelligence Squared US. Let’s get back to our debate. Paul, what, what do you think, Paul, in terms of the odds that there is other life out there, other intelligent life out there?

Paul Sutter

Uh, first, I’d like to say (laughs), if there are any wealthy individuals listening to this program that have a spare $10 million per year-

Jill Tarter

Do you have a big enough question to answer?

Paul Sutter

Uh, well, the questions that I’m personally interested in are the nature of dark matter and dark energy, and the ultimate fate of the universe. Uh, which, to me, is a very large question. And any scientist, uh, not just astronomer, any scientist is going to be absolutely engrossed and fascinated by their particular curiosity. And their question will be gigantic to them because that’s what they are passionate about.

Um, in terms of odds of, are we alone? The, the real answer is, as Dr. Tarter mentioned, we don’t know. We do not know. All the evidence we have so far says that we are alone, but we have not searched a lot. But we honestly don’t know. And so, the question becomes… This isn’t the first year of study, this isn’t the second year, this isn’t the second decade of the third decade of study. In all these searches for extraterrestrial intelligences that are capable of communicating with us, we have to ask, what have we learned? Yeah, it’s only $10 million a year, but that- that’s small for astronomy or government grants. But it… but it’s large for me. It’s not zero. And it is money that could’ve gone somewhere else.

And so, in these decades, in half a century of study, what have we learned? Have we put constraints on any of those parameters in the Drake equation through SETI research? Have we start to put probabilities and hard numbers? Have we approached a better understanding of the universe? Or, have we come to the same conclusion year after year, which is, it appears that we are alone?

Jill Tarter :

So, Paul, when SETI turned 50, more than a decade ago, um, I did a calculation that said, “All right, what is the, uh, volume of face space that we’re trying to search where we might find evidence of, um, information being transmitted between the stars?” And I said that that was a nine-dimensional volume. Let me see if I can remember the [inaudible

] (laughs). So, three dimensions of space. One dimension of time. Two senses of polarization. Um, an unknown modulation scheme. And finally, we don’t know how sensitive we need to be because we don’t know if there is some evidence how strong it is and how far away it is. So, those nine dimensions.

And then, I, um, said, “Okay, I’m no good at nine-dimensional visualization. So, let me, uh, make an analog and say the total volume that we might have to search, um, in those nine dimensions is equal to the volume of all the Earth’s oceans.” Right? I can… I can visualize that. And so, how much in the decades that you’ve spoken about, how much have we searched? And the answer was, uh, when SETI turned 50, it was one glass of water out of all the Earth’s oceans. 10 years later, students at Penn State d-… redid this calculation, it was more like a small hot tub, mainly because our computing is getting so much better and faster. But I would claim that, um, that’s too little an effort to make any large grand conclusions. And that there’s a lot more searching to be done. And, of course, that searching will get better and faster, mainly because of two things. [inaudible

] continued advance in computing capability. And, the introduction of machine learning.

So, in the past, we’ve taken data, which has normally been voltage output as a function of time coming out of a radio telescope. And we’ve asked of that data, “Does this pattern or that pattern exist in the data?” Now, with machine learning, we can think about simply asking, um, not for specific patterns, but if there’s any information content in that data. So, I’m excited about those new possibilities. And, um, I think that there is a lot more to be explored.

John Donvan

Paul?

Paul Sutter

I think you’re… I completely agree that the volume of the search space of the possibilities of intercepting a signal are enormous, but I think that’s a detriment because then we have to ask, is this meager amount, only $10 million a year, is that sufficient funds to ever search through this space of possible signals to such a degree that we can come up with a satisfactory answer or even some constraints? And if the answer is, “No, we need a lot more money. We need $100 million. We need a billion dollars a year in order to even attempt to answer this question in the next few decades,” um, then we do need to allocate serious resources to this.

Uh, but if we’re only going to allocate relatively minimal amounts of resources, then how could we ever hope to satisfactorily search that space and get an answer? We could spend a hundred years, a thousand years searching the… for possible signals and not find anything because we’re not spending enough resources. So, if we wanna do it, uh, we have to do it right, which means spending a lot more money than we are.

Jill Tarter

Actually, I, I, I… I’m, I’m, I’m happy to spend more money. But I don’t-

Paul Sutter

(laughs)

Jill Tarter

… actually think that’s the way to think about it. I think that what’s gonna happen in a decade, or a hundred years, or a thousand years, is that we are going to understand the universe better. We are going to develop new ways of explaining the properties of the physical universe. And given that, uh, we will have a better feeling for what is non-physical and what we might be, uh, discovering with our new tools and technologies. So, I think that, um, because we can’t… we, we can’t promise an answer, right? And the answer might be an unsatisfying, “No, we are in fact alone.” But that’s such an important question that I don’t think we should make any such conclusion until we have expanded, uh, resources, and time, and talent sufficient to warrant making a big decision like that.

John Donvan

Jill, w- when is… when is it a “no”? When, when do you know that the search has been fruitless?

Jill Tarter

Uh, when you can no longer convince folks to fund it, right? When you’ve just reached the end of peoples’ ability to be c-… to be interested and to decide that it’s worth doing, right? Or, or, you, in fact, find a “yes” as an answer.

John Donvan

But if you’re… if, if we’re already in a world where people are struggling over resources and there are, you know… Let’s just talk in terms of, um, if you run out of private funders, would the government be there when resources are needed increasingly for so many other things and we’re aware of not having sufficient funds for it? Uh, is, is it likely that that day, that, “No, it’s not worth it,” is gonna come sooner than later?

Jill Tarter

I think that universities found a, a good answer to this problem a long time ago, and that’s called an endowment. And so, you raise a significant amount of funds and you invest it and spend only a bit of the income from that investment each year. So, you can look forward to having a secure source of funding into the far future. And you work off of that amount of, uh, resource. And you plan for it. And this actually makes it a bit easier to recruit the best and the brightest, right? Because when you talk to some young, uh, scientist or engineer and you say, “Come work on this problem,” and they say, “Well, you know, I’m not sure I wanna work on something that might not pay off in my professional career lifetime,” um, that’s a hard sell. But there are a class of people, like myself, who think that this is important enough to work on.

But then if you have a second hurdle which says, “Oh, and, you know, maybe I can’t make budget, I can’t make payroll next month,” that makes it a really difficult sell. But I think an endowment, uh, for this purpose is a very good way to continue such a possibly low probability, but high payoff form of exploration.

Paul Sutter

Um, there are, you know, the question of, “Are we alone in the universe?” uh, contains within it the question, i-… did life appear on other places than the surface of the Earth? And that is a- a- an equally big question, an equally fascinating and powerful question. And a question that a lot of astronomers have devoted their careers to. A, a generational research on this problem.

And, at first glance, it appears to be a more promising avenue for scientific investigation. Because, presumably, this is just a guess, that intelligent life is more rare than regular life, uh, for various reasons. Again, this is just based on supposition. We only have our one example here. But we can dig up the soil on Mars, we can crack open the ice shells of the outer moons in the solar system. We can hunt for signatures of, of biology in the atmospheres of other planets. And we t-… In study, there’s a lotta talk about detectability and sending out radio signals, or building, uh, megastructures, or, or giving off some sign that we are here and we are intelligent. But, regular life is perfectly capable of giving off its own signals that are detectable. Because it can throw its environment out of equilibrium.

For example, two billion years ago, the Earth’s atmosphere had relatively little oxygen in it. But then once photosynthesis got really going, it’s filled our atmosphere with oxygen, to a detectable level. If there is another intelligent species out there in the galaxy and they have figured out things like telescopes and atomic spectra, and their own version of the James Webb Space Telescope, and et cetera, then just looking at the atmosphere of the Earth, they have known that there is life on the Earth for over two billion years. That is detectable over long time scales. And that is, in fact, one of the goals of the James Webb Space Telescope in future follow-up missions, is to hunt for signs of life in alien atmospheres.

And so, there is a large search space there, but it’s very well-constrained. And we know exactly what we’re looking for. We’re looking for bio signatures. And so, it seems much more likely in our lifetimes that we will find evidence for life because it’s much more easily detectable. And so, if SETI in future study searches need to rely on understanding new physics or potential new technosignatures, that seems more like an argument for funding the new physics and studying new physics and new engineering, rather than funding SETI. And in the meantime, we search for life of any kind.

John Donvan

So, so, in a sense, you’re saying that we could be searching for planet of the mushrooms, or planet of the ferns, something like that that, that would not be intelligent, but would be sending out a signal that there’s life there? It’s way less sexy than finding intelligent life. At least, to me. But I- I’m wondering, Jill, how do… how would you feel about the, the search for, for life more generally becoming the focus, rather than intelligent life?

Jill Tarter

No, I wouldn’t want it to become the only focus, right? I’m a huge fan of looking for life. But, Paul, here’s the question, how far away can you find that, right? Not how many… How many planet, exoplanetary atmospheres is James Webb actually going to be able to explore? There’s no gain in that signal, right? But, if you’re looking for engineered signals, then you can expect that the engineers at the other end of that communication channel will have put gain in it because they want that to be depectable over [inaudible

]-

Paul Sutter

What do you mean by putting gain in it? What does that term mean?

Jill Tarter

(laughs) I’m sorry. That means that you, uh, put a lot more energy into the transmission that you’re making, that you’re creating artificially than, um, you would need to be able to be heard just within your solar system. You actually generate some kind of signal that is detectable over the vast distances between the stars. And not just the handful of stars around our location in the galaxy-

Paul Sutter

Mm-hmm.

Jill Tarter

… whose atmospheres we could explore spectroscopically. So, you want to have whatever you do be detectable over a much larger volume of the galaxy than we can currently explore for life.

Paul Sutter

So, Jill, I, I, I assume when you’re talking about engineered signals, you, you mean something analogous to, you know, if, if, if I’m walking through the woods and there are some pebbles scattered around, that’s one thing. But if I’m walking through the woods and I see 10 stones stacked on top of each other, that tells me that somebody was there, somebody did that. And it sounds as though what you’re saying you’re searching for are signals in space that have that signature of somebody having done it on purpose. Sent something out there on purpose. Am I right about that?

Jill Tarter

Yes. That is the easiest thing to find. You could also be looking for things that are almost astrophysical. So, uh, someone who takes a variable star with a very discreet period and has the ability to orbit some energy source around that star. And the star varies p-… i- its luminosity varies periodically because the star expands and gets brighter, and then contracts and gets cooler. But, if you have the ability, so as the star is in its cool phase and thinking about getting ready to expand on this normal period, you zap it with some energy and cause it to expand prematurely, now, you have created a morse code. A, a normal long period and a shorter, uh, artificial period. So, you have a dash and a dot. And, uh, these variable stars are visible throughout the galaxy and actually into the nearest cluster of galaxies.

So, you might have done that kind of thing, which is almost astrophysical. Which, the kinds of things that Paul wants to explore would eventually pick it up. And some graduate student looking at, um, data in some huge archive might say, “Huh? What’s this?” Or, you could have a, um, a pulsar, right? A rotating neutron star whose magnetic axis and rotational axis are misaligned. And as it rotates around, if we’re in the line of sight, at every time that beams come around, it gives us a pulse. So, you could take and make an artificial pulsar. Now, the pulse goes from its normal period, to a different period. And, and we’ve seen that in pulsars because there are starquakes that, uh, change the, uh, center of mass of the rotating body and its period. But what we’ve never seen is a pulsar that goes from one period to a second period, and then back to the first. But you could do that with technology. So, there are lots of things that we could look for and over a much larger volume of the galaxy than we are able to explore for, uh, chemical anomalies in the atmospheres of exoplanets because of life.

John Donvan

More from Intelligence Squared US when we return.

Welcome back to Intelligence Squared US. I’m your host, John Donvan. Let’s return to our discussion.

Paul Sutter

So, in that volume, with present-day technology, yes, we are searching a smaller volume, but our stakes are also much lower. You… If intelligent life is rarer than non-intelligent life, then you need the larger volume to go out and find the intelligent life because it’s more unlikely for it to be close to you. But if the stakes are lower, if we’re just searching for any kind of life, then we can have a smaller volume and still increase our odds of success because we have so many planets accessible to us within a few thousand light years. And even in our own solar system, there is liquid water in, in the icy moons of the outer planets. Liquid water. They might be homes for life right in our backyard, and all we have to do is send a probe over to check it out. And so, the search space is much more promising.

Uh, but when it comes to technosignatures, these manufactured technological signs of intelligence, there was one particular incident a few years ago where a graduate student studying some Kepler data found a star that had a very interesting light curve. It would get brighter, and dimmer, and brighter very suddenly and very irregularly. And some SETI astronomers proposed that this was a technosignature, that there were some megastructure orbiting that star that was blocking out the light as it orbited that star. This, as you might imagine, created a lot of interest, a lot of public discussion. It turned out it was just dust. I distinctly remember sitting in the journal club of my astronomy department at the Ohio State University, where I was at the time. And when this, uh… these papers came out, uh, we discussed it and, uh, the astronomers in the room said, “Oh, it’s, it’s just probably dust ’cause dust you can blame on 99% of your problems in astronomy.” A- and it turned out to be dust. But in the meantime, a lot of people, lot of the public, believed that we had found signs of extraterrestrial life and we had found evidence for technological civilizations.

John Donvan

I, I wanna understand something about the, the kinds of distances that we’re talking about. And, a- an- and the, the possibility that if, if there are signals that are being sent deliberately or accidentally from intelligent civilizations elsewhere, that, those civilizations are long gone. That, uh, you know… I, I, I, I look at, you know, our just experience on Earth. Um, we’re out of sync with the, the Maya Civilization, for example, in, in, in Southern Mexico. Had its heyday 1,500 to 2,000 years ago. We, we missed, uh, in terms of time. They were simultaneous with the Roman Empire, but they had a distance problem. But we have a dis-… a time problem with the Roman Empire. We’re out of… we’re out of sync with them. And I would imagine that if there’s… if, if there’s a civilization sending a signal that was sent 2,000 years ago, yeah, fairly good chances that that civilization doesn’t exist anymore. What do you do with that fact?

Jill Tarter

Well, um, think about the fact that it’s not the longevity of the civilization that comes into this equation, but the longevity of the technology. Uh, we still make glass the same way the Romans made it. That technology has outlived the civilization that created it. We have satellites, [inaudible

] satellites in orbit around the planet that will be there for millions of years, right? Um, they may well outlive us. And, so, the… I did say that the temporal was one of the dimensions, the nine dimensions of space that we have to-

John Donvan

Right.

Jill Tarter

… search through. But it is possible that technologies can be lots longer lived than anything that we have experienced so far in terms of life on this planet.

John Donvan

But after a 2,000-year journey, even the technology may have collapsed or deteriorated in some form.

Jill Tarter

Well, the, the technologists may no longer be there, right? But you actually learn that at one time, or you infer-

John Donvan

Mm.

Jill Tarter

… at one time, there were technologist that did create that technology. So, you do answer part of the question.

John Donvan

Paul, you mentioned that there are a lot of planets that are potentially habitable, in terms of the, the water being out there, et cetera. Um, and one of the reasons that I think that this search for life goes on in a very, very broad sense, and Jill alluded to this in the beginning, is that, um, we, we main… we may need some sort of rescue, one way or another. Now, her argument was, the rescue will come from all of us recognizing our common humanity and all of us getting on the same team. But there’s also always talk of, can we get off this planet and go somewhere else? And with, with so many habitable planets out there, does the search for life… is the search for life at least justified by the idea of there being some sort of life raft out there for us?

Paul Sutter

Unfortunately, the universe is a very big place. The distances between stars are unfathomably e- enormous. We can write them down and we can say the numbers out loud. The next nearest star is about four light years away. That doesn’t communicate truly how far away that star is, how far away Proxima Centauri is. The distances between stars and the energy needed to travel among the stars is so great and so vast that even if we were to detect a habitable world within, say, a hundred light years, the amount of energy and technological sophistication and sheer dumb luck it would take to actually even send a tiny little spacecraft there is beyond even reasonable projections of our technological progress. The universe is a big place.

And I believe, I personally believe, this is based on no scientific evidence whatsoever, that we are not alone in the universe. The universe is a large place. And that there are probably other intelligent critters maybe having their own debate right now on their own radio show. Uh, but the universe is so big that we are effectively alone. And our planet, it really is the only option. There is no Planet B. That’s another great joke. Thank you.

John Donvan

The conditions… The, the, the odds are that the conditions for life are decent enough that there should be other, o-… there should be other life and there should potentially also be other intelligent life. And yet, so far, zilch in terms of real results. And there, there was an… In fact, it was the conclusion of, um, of a study done by Oxford University’s Future of Humanity Institute, basically made that argument. And, and, and it’s the… They were focusing on what’s called Fermi Paradox, which basically makes that point. Like, where, w- where is everybody if, if there… if the odds are out there for there to be life? We should have found it by now. We should have seen signals by now. The, the universe should be teeming with such signals. And th- that seems, Jill, often to be raised as a challenge to, to your argument. So I’d like you to take that on.

Jill Tarter

Yeah. Well, those are the same guys that showed that if you think about the factor in the Drake equation, the fraction of potentially habitable worlds where life actually starts, uh, in the literature, there are 120 orders of magnitude different estimates for that factor. So, it’s, it’s really unknown. Uh, I think that, uh, again, I go back to this having searched, um, a hot tub’s worth of water out of an ocean, of Earth’s oceans. We just really haven’t looked. And we’re… we don’t really yet understand how life could be different than all life as we know it.

So, I used to argue that, uh, we wouldn’t be able to tease out from the biology that we know what is necessary for life versus what is just contingent in the way it happened here. But this whole new field of synthetic biology in the laboratory, I think might give us a handle on that problem. I used to say we’d have to find a second example of biology in order to, to, to decide what was necessary versus what’s contingent. But laboratory synthetic biology may help us to understand and then, um, allow us to imagine life as we don’t know it. Life living in environments that we all learned as students would be totally sterile, right? And we’ve expanded our concepts of where life can… life as we know it, can thrive because of this whole, um, new science of extremophiles. Life living in places that you and I couldn’t tolerate for… at all.

John Donvan

Yeah, that’s an interesting point, Paul. That, that, when we’re looking for life, we send… tend to be, y- you know… We’ve already talked about water. Well, we need to water, so that makes sense to us that life needs water. But, could there not be life out there that doesn’t need water and that doesn’t need oxygen? And that has some other… some other functioning system? And therefore, the c-… the searching for life in the way that you’re talking about it might turn up some kinds of life, but we might be missing other kinds of life.

Paul Sutter

Oh, absolutely. Uh, who knows what wild varieties of life are possible and out there in the universe? And that is such a fun, such an engaging question. It also doesn’t have anything to do with SETI, for the search for intelligent life. This is just us exploring the universe and asking grand questions and having a great time. Uh, we focus on search for Earth-like life because we know what we’re looking for. There is a success condition. If we see an atmosphere that looks like the Earth’s, we have a high degree of, of certainty that we have found a habitable world ’cause we know what it looks like. But if you broaden the search too much to any kind of life, or any kind of signal, or any kind of sign, then the search is so broad and the space is so enormous that you don’t know if you’ll ever succeed. And you don’t know if you’ve already succeeded in the past because you’ve looked it over. So, by constraining our answers and limiting our focus, we know when we get the right answer. And that’s actually a big bonus, rather than a detriment.

Jill Tarter

Actually, I think that, that I would argue the opposite, that that’s a source of ambiguity, right? Um, my, my… I guess my most recent example would be the claim that we had found phosphene in the clouds of… cloud layers of Venus. And, at least on Earth, all production of phosphene requires biology, right? It’s biologically mediated. Well, it turned out it was a single line identification, wrong molecule, it’s probably SO2 rather than phosphene. Uh, but there’s a lot of ambiguity, uh, in the search for biosignatures. Perhaps there would be less ambiguity if you’re looking for something that’s obviously engineered.

John Donvan

Jill, when the day comes in your lifetime that an unambiguous signal is discovered from, from space, pointing unambiguously to intelligent life, what changes? W- what changes for you?

Jill Tarter

Oh, well, I think everything changes, right? We now have a new way of viewing ourselves in a new context. And I think it will change philosophy, it may change some religions. It will certainly encourage us to build tools for scientific exploration that can find other examples. Somebody, some source, something telling us what we should believe about some subject. Science is about exploration to find out what is. And so, in philosophy, there has been a millennial, uh, cyclical argument about the plurality of worlds, right? And it’s a… You know, whoever (laughs) [inaudible

] gets to tell you what you should think about that. And I, I, I find it totally unsatisfactory.

So, if we were to detect evidence of someone else’s technology, then we would get into philosophical questions about, “Is their God the same as our God?” Right? And it’s, uh, uh… I’m not a philosopher. You can see I don’t have a lot of, um, empathy for that approach to trying to understand the universe we live in.

John Donvan

But what would be the implication, do you think, for our self-perception if we learn that, you know, after, after several millennia of considering ourselves kind of top of the food chain, cop… top of the process of, of development of, of life on this planet, that in the universe somebody’s doing way better than we are in terms of sophistication and intelligence and technology, that they’re better, they’re stronger, they’re faster, and we’re not the king of the hill?

Jill Tarter

Yeah. I think what we learn there is that it’s possible to have a long future. Because I don’t know how another technological civilization gets to make the progress that you’re alluding to, and that they can do things far better than we are, if they’re not older. And so, I think that, um, learning that there is someone who’s made it through this technological, um, adolescence, that stage that we find ourselves in, is hopeful because even if they don’t tell us how to do it, the fact that they exist is a proof of a po-… of the fact that it is possible to get there. And we have to figure it out. So, I take that all as hopeful.

John Donvan

Okay. And, Paul, I wanna give you the last word. Any final thought on this?

Paul Sutter

I think the search for, or the question of, “Are we alone in the universe?” is a powerful question. It is a beautiful question. And, like I said at the beginning, I would never, ever tell someone not to follow their curiosity ’cause that is at the heart of science, and the heart of philosophy, and the heart of humanity. Um, but we are surrounded by questions. We are surrounded by a universe that we do not understand. And there are other, many more other powerful, other beautiful questions that we can ask and we can inquire about. And I wish we had, as scientists, infinite money and infinite resources so that we could pursue every question, uh, that comes into our hearts and into our minds. That would be wonderful. But we don’t. Astronomy does not have enormous amounts of funding compared to other avenues of science. And certainly not compared to, say, overall federal budgets.

So, we do have to decide what we do with our limited resources. We do have to decide what we want to investigate. What is the most promising avenues for a success for learning about these universe? How do we balance all these thousands of astronomers with their individual burning questions, uh, that, that keep them up at, at night and that makes them want to show up day, after day, after day to their laboratories, or their chalkboard, or their observatories? And the search for extraterrestrial intelligence can certainly come into that discussion, of course. But ultimately, we need to balance it against everything else we wanna know about the universe.

John Donvan

All right. Paul Sutter and Jill Tarter, thank you so much for joining us to discuss the… and debate the question of whether we should be searching for life in space. We really appreciated having you on Agree to Disagree.

Paul Sutter

Thank you so much.

Jill Tarter

It’s been a pleasure.

John Donvan

And I’m John Donvan. We will see you next time.

And the conversation you just heard perfectly captures why we do this. Y- you know how discourse happens these days in our culture. It is pretty broken. And it’s why it is so refreshing but also unusual to hear two people who disagree about something actually be able to converse civilly and rationally, and explain things and shed light, not just blow smoke. And we know from so many of you that’s exactly why you listen to our programs. And, why I would like to remind you that as you turn to us for that, we turn to you for support because we are a nonprofit, and it’s contributions from listeners like you that keep us going. So, please consider sending us a buck or two, or 10, or 50, whatever you can handle, whatever works. And that’ll give you a stake in what we’re doing here each week. And, it will mean that we are here next week and beyond that. Thanks so much. Once again, I’m John Donvan. And we’ll see you next time.

Thank you for tuning into this episode of Intelligence Squared, made possible by a generous grant from the Laura and Gary Lauder Venture Philanthropy Fund. As a nonprofit, our work to combat extreme polarization, through civil and respectful debate, is generously funded by listeners like you, the Rosenkranz Foundation, and friends of Intelligence Squared. Robert Rosenkranz is our Chairman. Clea Conner is CEO. David Ariosto is Head of Editorial. Julia Melfi, Shea O’Meara, and Marlette Sandoval are our producers. Damon Whittemore is our Radio Producer. And I’m your host, John Donvan. We’ll see you next time.