Lisa Kaltenegger: Looking for Life on Other Earths

Lisa Kaltenegger
I’m Alan Alda and this is C+V, conversations about connecting and communicating.
Lisa: If you find even a speckle of life somewhere, what that means is that life must be everywhere, it must be distributed throughout the cosmos. I think living in a world, where you look up at the sky and you know that around all of these other stars, there are planets and there’re some life forms, whatever shape they take, I think just puts me into even a deeper connection with the cosmic surroundings.
That’s Lisa Kaltenegger. She’s an expert at figuring out to tell which of the billions of planets out there might have life on them. She’s finding ways to read the skies that are ingenious. And she’s awfully good at explaining it.

Alan: This is great, that you can be on the show, because you are such a good communicator. You’re clear and vivid and you’re funny too.
Lisa: Thank you very much.
Alan: Great to have you on the show. I heard you say once that you hope to find life on other planets in our lifetime. It’s kind of an obvious question, but I’m kind of curious to know what your answer is to the question why.
Lisa: One of the things that I’ve found most amazing, I find most amazing about the time we live in is that we live in a time that humankind, for the first time, has the technology that we can actually figure out whether we are alone in the Universe. What I mean by that is we know how to look for signs of something breathing on another planet; the oxygen in our air, for example, the methane, the CO2. So the mix tells you whether or not there is a living organism on another world. We are building, right now, the telescopes who will be big enough to get enough light collected to be able to look at that for a planet like the Earth orbiting a star that is so far away.
Alan: It’s so interesting the indirect ways you have of figuring out that there’s probably life. The wobble of the star, tell me more about that.
Lisa: So, the first step in all of this is trying to figure out if there’re actually planet around other stars. So what we have is most of these thousands of planets… We have more than 4,000 planets that we confirmed. We know more than 4,000 planets orbiting other suns, other stars. So, when you go out at night and see a star up there, every star basically has at least one planet. So you’re looking at other planetary systems, even though you can see the plants because they’re too small. But the way that we figure out that they are there is we are very, very precisely looking at their stars. If the stars move, the wobble movement, then that tells you that something tucks on the star and makes it move.
Lisa: Usually, in class, I always talk about go to a park, and you see somebody who leans back really strongly, you don’t have to see the dog that tries to go in the direction the owner doesn’t want to go to know that this person is being pulled. So a similar thing we do for stars. So when-
Alan: The planet is pulling the star-
Lisa: In one direction.
Alan: … as it makes its orbit.
Lisa: Orbit the star. So they orbit around the center of mass. But basically you can think about it exactly like a dog pulling in one direction and you leaning back to keep the position. And then if the dog were running around you, you would just basically wobble back and forth trying to keep your position. The more massive the dog, so the bigger the dog, the heavier the dog, then the more you’re going to wobble or the more you have to lean back to keep that stability. So this is why-
Alan: So you can tell from the wobble how big the planet is?
Lisa: Absolutely.
Alan: What if there’s more than one planet? Is the wobble more chaotic or what?
Lisa: Yes. So basically then the wobble is an overlaying of different motions. So you can see, for example, for our own sun, you can see the back and forth movement due to Jupiter, our biggest planet, every 11 years. On top of that, every one year, the sun moves back and forth because of the Earth. So for each planet, it has a specific movement, and when you look at the movement of the star and you say, “Ooh, there’s one movement it does in one year, there’s one movement it does every 11 years.” This is how you can then tease out how many planets go around the star.
Alan: So you’d have to study the stars’ wobble or wobbles for many years before you could get a picture of how the patterns can be teased out into planetary motions.
Lisa: Absolutely, when you have a system like our own where Jupiter takes 11 years. But what we found is that most other systems… Again, that’s a little bit of a biased observation because they’re easier to find, are more tightly packed. So what that means is that we’ve found planets that only need about four and a half days to go around those stars or even 18 hours, not even a day. The four and a half days, the one that just got the Nobel Prize, 51 Pegasus B, the first one that we found, about the mass of Jupiter, but in the four and a half day orbit, so Monday morning to Friday afternoon and the year’s over, and you can celebrate your birthday again.
Lisa: So, there are so many different planets out there, and looking at our own system just gives us this one view. But now we have thousands of other planetary systems and we’ve figured out, “Ooh they can be big and small.” Some of them are so hot that any rock we know would melt on them, we call those lava worlds. So they would have liquid water. Oh sorry. So they would have liquid lava all over the surface. So those are the ones in the 18 hour orbit or like couple of day orbit, very close to their stars. We also find some that are much bigger than [inaudible 00:28:47] and very fluffy, but they go around their stars in… I don’t know, a month or something.
Lisa: So we find this whole diversity, and all of it is still a little bit biased, because we can find the ones that are closer to the star faster and so our view of these other planetary systems is a little bit shifted towards, “Ooh, there’re so many small and very close by planets.” Because if you wanted to find Jupiter, you’d have to look for about 11 years, and we haven’t done that yet, not for many stars.
Alan: I’m sort of interested in the odds in favor of these various layers of understanding or meeting up with… For instance, I think I’ve heard you say that one out of five planets are ideally situated from… just the right distance from their sun to possibly be Earth-like. Is that right, one in five?
Lisa: So what we found, absolutely, is one in five, so one in five stars have a planet that’s at the right distance-
Alan: Oh, one in five stars. I see.
Lisa: One in five stars has a planet-
Alan: That’s a lot of stars.
Lisa: That’s a lot of stairs. Because in our own galaxy, we have a bad 200 billion stars. So if it’s one out of five, that could potentially be an Earth, because we don’t know what it takes to actually start life. We can’t make life in the lab, so we don’t know yet. But one out of five in a galaxy, our own, has about 200 billion stars. So we’re talking about 40 billion potential Earths. So in a way, even if life is really hard to make for whatever reason, we don’t know yet, I like the odds that we are facing.

MUSIC BRIDGE

Alan: The movement of the planet, any planet, across its star relative to us, we see [inaudible 00:29:26]. That seems to give us two bits of information. One is darkening the star momentarily and the other is that we see its chemical composition because we can analyze the light coming through its atmosphere. Is that close?
Lisa: Absolutely. That’s exactly right. So when you look… The second method we have, transiting method is what we call it, is basically, you look at this hot, bright star. It’s bright because the surface is so incredibly hot, like for the sun. So sometimes we see the stars become a little bit less bright, and that’s due to a planet going between us and its star. So it just, for a little bit of time, blocks this hot or part of this hot bright surface from our view so it appears as if the star becomes a little bit less bright. But it’s just because we don’t see the full surface. As soon as the planet goes out of our point of view, our line of view to the star, we see the full brightness again.
Lisa: While that is happening, if the planet is just between us and the star, part of the stellar gets filtered through the air of the planet before getting to us. Light is energy. If you go outside, your hand gets warm if it’s in the sun. So light can actually hit a molecule or an atom and interact with it. For example, think of a molecule. It will start to swing and rotate if the right amount of energy hits it, just the exact right amount. So, when I look at the light that comes from the star that has been filtered through the planet’s atmosphere, there is some light missing. That missing light uniquely tells me what the chemical composition of the atmosphere of the planet is, because ozone for example, three oxygen atoms, swings and rotates differently than, for example, CO2, C and two Os. So basically, I know exactly, by the energy that’s missing, what is the chemical makeup.
Alan: So you get the… The light comes through a prism, or it’s as if it’s coming through a prism-
Lisa: Exactly.
Alan: … and it breaks up into different colors. Are the colors different? Like, going from yellow to red, there’s a spectrum there. So somewhere in there is one kind of gas, in someplace else, there’s another kind of gas or what?
Lisa: Exactly. So basically, if I see… This is now made up because it’s a very specific… Okay. Exactly. So if I see some light, like the green is not as bright as it should be, I can tell you what chemical that actually is. If the light blue is not as bright as it should be, I can tell you, “Ooh, there is another chemical in the air, like water.” If I say, “Ooh, the yellow is not as bright as it should be…” But it’s always a specific yellow, it’s not the whole yellow, because this energy that hits a molecule is a very specific wavelength, a very specific sub color.
Lisa: By looking which of the sub colors are basically not enough, the light’s not enough, there should be more, that tells me which molecule it hit or which atom it hit. I know because I can do this in the lab. I can have a gas, I shine the light onto it, and I measure what comes out on the other side, thus I have a template to know, “Ooh, this light yellow isn’t there, so it’s this chemical.”
Alan: So this is kind of an obvious question, you don’t have to do this on the fly. You have a machine that reads the color. Is that right?
Lisa: Absolutely. So the light comes in, and it goes over something like a prism. So then you say, “Okay, so what are the intensity levels of the different colors?” And that gets printed on the computer, and then you can see, “Ooh, so this is missing.” It flags what is missing, and that tells you, “Ooh, at this wavelength, that is this chemical.”

Lisa: So we now had to look for it, and we’re building the light buckets, basically, because light is going for free through the Universe. Lights going for free through the Universe, the only saying we have to do is actually catch it. So the bigger the telescope, the more off the light we can catch. If you think about it, if you put the Earth a hundred times next to each other, that’s about the diameter of our sun. So it’s tiny next to a really bright star, but we’re on the verge of having the technology to peek into that ear on another world and figure out if there is something breathing there too.
Alan: So your hope to find life on another planet is to answer the question, are we alone? That’s what it sounds like. But will you still feel we’re not alone if we find the life that some little speck of something that takes in oxygen and puts out methane or something? How developed does a life have to be for you not to feel alone?
Lisa: I honestly have to say that I think life is incredibly fascinating, and trying to figure out what life would develop into on a completely different environment is what I find fascinating. So in a way, when I talk about life, I don’t talk about you and me, even so that would be great, if we could find life then we could even communicate with. Of course, normally the joke that I have in my astronomy class is like, better speak English because first you have to figure [inaudible 00:03:13] to communicate. [crosstalk 00:03:14].
Alan: Yeah, right. You can feel pretty alone even if you both speak English.
Lisa: Absolutely. That is true too.
Alan: It is the cause for half of all divorces, I think.
Lisa: Yeah. But I think the key point is if you find even a speckle of life somewhere, what that means is that life must be everywhere. Because if we can find a speckle of life somewhere with the technology we have, while it’s not that great yet, we’re just at the verge of being able to find those things, then it must be distributed throughout the cosmos. I think living in a world, the way you look up at the sky and you know that around all of these other stars, there are planets and there’re some life forms, whatever shape they take, I think just puts me into even a deeper connection with the cosmic surroundings.
Alan: Do you think that… Is there any evidence… except what we’ve experienced, which is sort of anecdotal, because all we know is us. Is there any thinking that gives us the idea, in a reasonable way, that if there’s any kind of life, it will probably evolve into intelligent life or might it just stay forever at what we think of is a lower level?
Lisa: I think you already raising a couple of really interesting questions here, and one of them is like, what’s intelligent, right?
Alan: Yeah.
Lisa: Because we are assessing intelligence because we can communicate with different life forms, and thus we’re assessing what we perceive as being intelligent. So for example, if you have this tiny, tiny life form, it’s called a tardy grid or water bear that lives-
Alan: My favorite animal. I love them.
Lisa: Me too.
Alan: They can live anywhere, it seems.
Lisa: They can live anywhere, it seems. But whether they’re intelligent is a huge discussion that people are having, because we can communicate. So the question is like, intelligent life, when does it develop? When can we figure out that it’s actually intelligent? Even on our own planet, I think there’s way more intelligent life forms than we give them credit for for now. But of course, the second question that you packed into this is like, well, there is life, there is maybe even intelligent life, but there’s intelligent life or life we can communicate with, that we can interact with, and maybe ask even questions. I think we have tiers of life that we’re looking for. But I think for starters, I’d be happy to find any life, and everything after that is the cherry on top.
Alan: I’m sort of interested in the odds in favor of these various layers of understanding or meeting up with… For instance, I think I’ve heard you say that one out of five planets are ideally situated from… just the right distance from their sun to possibly be Earth-like. Is that right, one in five?
Lisa: So what we found, absolutely, is one in five, so one in five stars have a planet that’s at the right distance-
Alan: Oh, one in five stars. I see.
Lisa: One in five stars has a planet-
Alan: That’s a lot of stars.
Lisa: That’s a lot of stairs. Because in our own galaxy, we have a bad 200 billion stars. So if it’s one out of five, that could potentially be an Earth, because we don’t know what it takes to actually start life. We can’t make life in the lab, so we don’t know yet. But one out of five in a galaxy, our own, has about 200 billion stars. So we’re talking about 40 billion potential Earths. So in a way, even if life is really hard to make for whatever reason, we don’t know yet, I like the odds that we are facing.
Alan: So we’ve got odds like that. It’s hard to figure the odds on my next question, I think, which is, what are the odds of finding life as intelligent as us? What are the odds of finding life more intelligent than us, or finding life that even looks like us, that there seem to be diminishing returns as you go down that path.
Lisa: Oh, I completely agree with you. But I would just turn it around and say like, life that doesn’t look like us might be even more interesting, because why would everything go through the same exact path of evolution? You would need-
Alan: It seems so unlikely, doesn’t it?
Lisa: Right. Absolutely. You would need the dinosaurs, you would need them to die out. However, one of the things that’s really interesting in science, what we see is that life can adapt to many different environments. So even if the environment were very different, instead of thinking about it as a tree of life, what’s the old thinking, you can think about what you see is just the one life that was best adapted to our environment and then it branched out. So if the environment were a little bit different, most scientists agree that life would just have started out differently. For example, if you just think of a harsh radiation environment, for example, a lot of these small red suns have harsh UV radiation, then maybe we would glow, because bioflorescence is one of the methods here in Earth that life uses to break down this harsh UV radiation into harmless, visible radiation.
Lisa: So how intelligent life might look like us, might not look like us, I think that’s the other really interesting question in this whole search. Of course one other thing-
Alan: Sorry, go ahead.
Lisa: Sorry. One other thing-
Alan: Start again.
Lisa: Okay. So, of course one other thing we haven’t talked about is that it’s not just the search for life. What I also want to know is if you find enough Earth-like planets out there, you’ll get the first inkling of what the evolution of an Earth-like planet is really like because we haven’t found many older Earths yet. But whether you’re interested in whether there’s life out there or not, what you should be interested in is the future of our own planet. So the search will also give us that information, how does an Earth-like planet work from the beginning to the end? We know how our sun works because we see stars like the sun when they’re really young and when they’re older than us, so we know what our son is going to become in the future. If we could do the same thing for an Earth, again, it’s statistics, it doesn’t have to be a one-on-one, but that would give us a first glimpse into a potential future, what’s coming.

MUSIC BRIDGE

Alan: I’m wondering about the variety that exists in life on our planet, and what if that same kind of variety exists in other worlds? For instance, our planet, as far as I understand it, started out with anaerobic life, and then there was this big shift to aerobics life, which is what we enjoy. We still have anaerobic life in tin cans that go out of date, right?
Lisa: Absolutely.
Alan: And puff up the can a little bit. So what if there are planets that are anaerobic? Would we still find them the way you are searching for life presently? What if we have planets that have somehow found a way… or is this too crazy that they’ve somehow found a way to have life without water?
Lisa: Well, these are a big questions in science right now. So for the anaerobic, we use the young Earth as our template, and we say, what was the life forms on the young Earth and how could we look for them? Initially, the problem is that life forms… So we are basically looking at other planets and we’re looking at the air on other planets to figure out whether or not they are gases that shouldn’t be there that are basically… the only reason that we think they are there is because life made them. So we can spot that in the air of another planet or on the surface of another planet, think algae bloom or think green vegetation.
Lisa: So for anaerobic, we go back in time for the Earth and we say, what were the unique signatures that we could look for? The further you go back in this anaerobic regime, the more non-unique these signatures become. Because if biota now makes CO2 or methane, that can also be made by volcanoes. So it’s really hard to pick up life on anaerobic worlds. We have some idea, but it’s going to be very hard to say uniquely, I’m sure this is life. But then nature did something interesting. So it basically developed to the point… And biologist will argue that every life form will do that. It will develop to the point where something will produce oxygen and something else will use it, because you gets so much energy out when you can use oxygen.
Lisa: So they say it’s a normal part of this evolution on any planet. But of course, as you said before, we have an example of one, so it’s very hard to extrapolate from that. But if that is true, then what were you looking for, this golden fingerprint or this light fingerprint that indicates life on the Earth, that’s the combination of oxygen or ozone with a reducing gas like methane. Because if you have oxygen and methane, it will actually produce CO2 and water really fast. So if you still see oxygen in the atmosphere when there’s a reducing gas around, that tells you something produces oxygen in huge amounts. If it’s a temperate planet, our only explanation is that it’s life.
Lisa: So this is the ladder that we go down. From everything we know, and again, sample of one, we expect other planets to go through the same evolution, but how much time they need for each evolution step is a completely open question. Also, one of the really interesting things is the evolution timescale on the Earth’s norm. So after 4 billion years, basically four and a half, you arrive at us or something like us, or are other planets faster or are other planets slower in evolution? So that’s another thing that we can actually look for when we look for planets around other stars. It’d be really interesting to see how we fit in in terms of evolution fastness; are we the fastest, are we the slowest, are we somewhere in the middle?
Lisa: It will also answer a lot of questions we have, for example, the bombardment on early Earth. Is that something that actually helped evolution, or is it something that hindered evolution? Again, example of one, it’s very hard to make any conclusions. But if we had a second Earth, a third, a fourth, a fifth, we could actually check in a way the age and what we see in terms of diversity of life. So it would answer a lot of questions we have about our own planet too.

MUSIC BRIDGE

Alan: When you were talking about intelligent life that we might try to communicate with… We already have, it seems to me, intelligent life that we might try to communicate with, at least maybe to practice for when we find life someplace else, assuming we’d find it and then be able to communicate with it, because that’s not going to be so easy either. But we’ve got… Excuse me. We’ve got octopuses that are really smart and whales and dolphins, and they seem to… The whales and dolphins seem to communicate with each other pretty well. Should we practice trying to learn to communicate with them so that we get techniques that we can use if we contact creatures out in space?
Lisa: Oh, absolutely. I completely agree with that. What I use in class nowadays is that I say, “Look, have you ever tried to talk to a jellyfish, communicate with a jellyfish?”
Alan: Actually, I try running when I get a jellyfish [inaudible 00:15:24].
Lisa: See if you could communicate with a jellyfish to tell it, stop, stay where you are. I was swimming here. It would be so much more useful.
Alan: Have you ever tried to do that?
Lisa: Not with any success. But I completely agree. I think this communication is also… I feel that it needs to be studied much more. Of course, one of the latest movie was Arrival, was actually bringing to a beautiful point because it was basically making this point that we always expect there to be a message in plain English or in prime numbers. But this science fiction story and then their consecutive movie basically had this whole idea that you have to establish a language. In that movie, or in that story, it actually works because you have visual contact, so you can actually say, “Look, this is me walking.”
Lisa: So it would be much, much harder if you don’t have that visual contact. But the strategies that we do employ and that we’re starting to learn of how to communicate with dolphins and whales and octopus as you were saying, are definitely the first steps towards trying to come up with something uniform or universal, to come up with something universal that we could use to try to communicate if the situation arises.
Alan: Maybe by the time we find out that there’s life and can actually communicate with somebody, maybe we can use quantum computers that’ll be developed by then to crack the code of their language.
Lisa: Absolutely. I think one of the interesting things is that if we learn how to communicate better, I very much hope that we’ll use it for our own world too. Because as you said before, a lot of the problems in our own world is because of communication. Even if you see somebody and speak the same language, it’s not coming how you intended to get there. So I think we can all learn from this research too.
Alan: So it seems to me that the problems of communicating across the galaxy are so great that the chances of finding a civilization that can communicate with us, that’s less developed than ours, are lower than the chances of finding one that’s way advanced. If they are way advanced, are we then in the position of the aboriginals of the countries that got colonized and used as slaves? I think it was either Stephen Hawking and Martin Reese who worried about that. “Let’s not contact them,” they say, “we don’t know who they are.”
Lisa: Stephen Hawking was worrying about that. The interesting thing is… There are two interesting things in this. One, if you’re worried about this at all; the distances in the cosmos, the distances between stars are a huge. So, if you take all the planets in our solar system and you shrink it to the size of a cookie, the next star over, our neighboring stars, so the sun’s neighboring star, Proxima Centauri is two football fields away in the same scale. So it’s a huge distance.
Alan: How many light years is that?
Lisa: About four light year. So if you were to call [inaudible 00:18:29] and you better have a good question, because it’s four years until it gets there and then four years later you’ll get your answer. So formally, the question [inaudible 00:18:37] communication as we were talking before.
Alan: The answer you get is, can you hear me now?
Lisa: Yeah. Probably. We’re probably going through the exact same drill than you do in a normal phone call. But the key thing is, I think, that we are very much biased by the problems we had of evolving. I have high hopes, and I’m a positive person, thinking that we’re actually going to evolve in the future into a civilization that’s not going to kill each other as much as we did in the past. So, one thing is the distances are so vast that for anybody to come and use us as a slave, there would have to be a super compelling reason, because it’s going to take energy and it’s going to cost a lot and it’s going to be a really long, boring journey. So, the question is like, what will be important enough? I do love us, I think we are great, but we are really no better slaves than a robot you could do. Because if you can do space travel, I don’t think you need the human physiology to carry something for you. So-
Alan: So you’ve thought about this.
Lisa: I have thought about this because my students ask this a lot in classes, and also that’s what sci-fi movies are often based on. The funny part is there were some intelligent aliens, they go to California to get water, and you’re like, if you’re an intelligent alien, you should know where the water is. But having said that, even we are like… A lot of asteroids that are going around in our own system and the comets, they have a lot of waters. So it makes no sense whatsoever, except for a good plot where you need to hear and so on, all good, to actually go to another store to get something like natural resources like water or whatever else you want to come up with, because it will be available in your own system, much closer, much cheaper, much easier to get.
Lisa: So I think our view of how an interaction could play out is very much biased by history, where it didn’t work out like it should have. As you said, with the aboriginals and the native Americans, definitely not the way to go. But if you’re still worried, there is another sci-fi that’s actually appropriate, and that’s The War of the Worlds. Because if you’re a [inaudible 00:20:51] based life form and we think that… Carbon is everywhere, so carbon makes a lot of sense for being the backbone of life everywhere. There are some other options, but with this temperature range that we have here, water and carbon are most likely.
Lisa: So if a carbon based life form lands here, it’s probably going to have the exact same problem that you have when you fly to another continent for vacation. You have [crosstalk 00:21:16] all these different vaccines… [crosstalk 00:21:18] Interstellar vaccines.
Alan: Jet lag.
Lisa: That too, but the interstellar vaccines, I think, will be something that will be very hard to get. In The War of the Worlds the bad, bad aliens die because the bacteria and the viruses basically kill them. So I think you can also think that this is one of the other reasons why you probably would not want to land and make slaves even if you go that far. So anyway, I think our vision is a little bit shaped by the movies we see and by the historic mistakes we made. So because travel is so difficult and it’s so far between stars, I have high hopes that we’ll get to the point where we’re going to have a better suggestion than to go there and kill everyone. So that is my solution. Also, if anybody ever comes and tries to talk to us, I hope they’re… Like I said, space travel, they’re advanced enough not to come and try to kill everyone, because why? There’s really no good reason why you would want to do this, kind of.
Alan: I know, but you’re counting so much on logic and wisdom. We’ve been around for only a few hundred thousand years, but we haven’t developed much-
Lisa: I agree.
Alan: … in that process.
Lisa: However, having said that, to get to a space [inaudible 00:22:37] technology, I think you have to go with more technology [crosstalk 00:22:40] wisdom and logic.
Alan: Wisdom will come [inaudible 00:22:44]. I hope you’re right. What do you think…
After this short break, Lisa tells me how growing up in a small town in Austria led her all the way out to the rest of the cosmos.

MIDROLL
This is Clear + Vivid, and now back to my conversation with Lisa Kaltenegger.

It seems to me that you’ve already accumulated enough information to figure out that there probably is life. What do you need to be definite about that?
Lisa: So, I’m a scientist. So we do not know how easy it is life to develop life, and we do not know… So I’m a scientist, and so do not know yet how easy it is to evolve life, what you need for it. Even so, there are so many places that could be like Earth, we do not yet know if that means that life will develop everywhere or nowhere except here in the Earth. But that bigger surprise as a scientist would be if we find nothing, because then we have to figure it out what would have been so incredibly special here on Earth for life to get started here and not else.
Lisa: It’s a worse result in the search, but it’s again really stimulating trying to figure out why would this be so different here? We have no indication so far that our planet is different from these other planets we found, but we have not yet figured out what the atmospheric makeup of these planets is. They should have water like we have here in the Earth, they should have a lot of carbon, they should have a lot of oxygen, just basically normal building block of all the Universe.
Lisa: So yes, I sound very positive and very happy about the search because I think it’s one of the most fascinating adventures humankind has ever undertaken, and we live in the right time that if life is everywhere, we’ll be able to find it. However, I do not know how widespread life is in this Universe, in this cosmos. So that’s, again, why it’s so incredibly interesting to search, to be able to figure that out.

Alan: It’s so interesting the indirect ways you have of figuring out that there’s probably life. The wobble of the star, tell me more about that.
Lisa: So, the first step in all of this is trying to figure out if there’re actually planet around other stars. So what we have is most of these thousands of planets… We have more than 4,000 planets that we confirmed. We know more than 4,000 planets orbiting other suns, other stars. So, when you go out at night and see a star up there, every star basically has at least one planet. So you’re looking at other planetary systems, even though you can see the plants because they’re too small. But the way that we figure out that they are there is we are very, very precisely looking at their stars. If the stars move, the wobble movement, then that tells you that something tucks on the star and makes it move.
Lisa: Usually, in class, I always talk about go to a park, and you see somebody who leans back really strongly, you don’t have to see the dog that tries to go in the direction the owner doesn’t want to go to know that this person is being pulled. So a similar thing we do for stars. So when-
Alan: The planet is pulling the star-
Lisa: In one direction.
Alan: … as it makes its orbit.
Lisa: Orbit the star. So they orbit around the center of mass. But basically you can think about it exactly like a dog pulling in one direction and you leaning back to keep the position. And then if the dog were running around you, you would just basically wobble back and forth trying to keep your position. The more massive the dog, so the bigger the dog, the heavier the dog, then the more you’re going to wobble or the more you have to lean back to keep that stability. So this is why-
Alan: So you can tell from the wobble how big the planet is?
Lisa: Absolutely.
Alan: What if there’s more than one planet? Is the wobble more or what?
Lisa: Yes. So basically then the wobble is an overlaying of different motions. So you can see, for example, for our own sun, you can see the back and forth movement due to Jupiter, our biggest planet, every 11 years. On top of that, every one year, the sun moves back and forth because of the Earth. So for each planet, it has a specific movement, and when you look at the movement of the star and you say, “Ooh, there’s one movement it does in one year, there’s one movement it does every 11 years.” This is how you can then tease out how many planets go around the star.
Alan: So you’d have to study the stars’ wobble or wobbles for many years before you could get a picture of how the patterns can be teased out into planetary motions.
Lisa: Absolutely, when you have a system like our own where Jupiter takes 11 years. But what we found is that most other systems… Again, that’s a little bit of a biased observation because they’re easier to find, are more tightly packed. So what that means is that we’ve found planets that only need about four and a half days to go around those stars or even 18 hours, not even a day. The four and a half days, the one that just got the Nobel Prize, 51 Pegasus B, the first one that we found, about the mass of Jupiter, but in the four and a half day orbit, so Monday morning to Friday afternoon and the year’s over, and you can celebrate your birthday again.
Lisa: So, there are so many different planets out there, and looking at our own system just gives us this one view. But now we have thousands of other planetary systems and we’ve figured out, “Ooh they can be big and small.” Some of them are so hot that any rock we know would melt on them, we call those lava worlds. So they would have liquid water. Oh sorry. So they would have liquid lava all over the surface. So those are the ones in the 18 hour orbit or like couple of day orbit, very close to their stars. We also find some that are much bigger than [inaudible 00:28:47] and very fluffy, but they go around their stars in… I don’t know, a month or something.
Lisa: So we find this whole diversity, and all of it is still a little bit biased, because we can find the ones that are closer to the star faster and so our view of these other planetary systems is a little bit shifted towards, “Ooh, there’re so many small and very close by planets.” Because if you wanted to find Jupiter, you’d have to look for about 11 years, and we haven’t done that yet, not for many stars.
Alan: The movement of the planet, any planet, across its star relative to us, we see [inaudible 00:29:26]. That seems to give us two bits of information. One is darkening the star momentarily and the other is that we see its chemical composition because we can analyze the light coming through its atmosphere. Is that close?
Lisa: Absolutely. That’s exactly right. So when you look… The second method we have, transiting method is what we call it, is basically, you look at this hot, bright star. It’s bright because the surface is so incredibly hot, like for the sun. So sometimes we see the stars become a little bit less bright, and that’s due to a planet going between us and its star. So it just, for a little bit of time, blocks this hot or part of this hot bright surface from our view so it appears as if the star becomes a little bit less bright. But it’s just because we don’t see the full surface. As soon as the planet goes out of our point of view, our line of view to the star, we see the full brightness again.
Lisa: While that is happening, if the planet is just between us and the star, part of the [inaudible 00:30:36] gets filtered through the air of the planet before getting to us. Light is energy. If you go outside, your hand gets warm if it’s in the sun. So light can actually hit a molecule or an atom and interact with it. For example, think of a molecule. It will start to swing and rotate if the right amount of energy hits it, just the exact right amount. So, when I look at the light that comes from the star that has been filtered through the planet’s atmosphere, there is some light missing. That missing light uniquely tells me what the chemical composition of the atmosphere of the planet is, because ozone for example, three oxygen atoms, swings and rotates differently than, for example, CO2, C and two Os. So basically, I know exactly, by the energy that’s missing, what is the chemical makeup.
Alan: So you get the… The light comes through a prism, or it’s as if it’s coming through a prism-
Lisa: Exactly.
Alan: … and it breaks up into different colors. Are the colors different? Like, going from yellow to red, there’s a spectrum there. So somewhere in there is one kind of gas, in someplace else, there’s another kind of gas or what?
Lisa: Exactly. So basically, if I see… This is now made up because it’s a very specific… Okay. Exactly. So if I see some light, like the green is not as bright as it should be, I can tell you what chemical that actually is. If the light blue is not as bright as it should be, I can tell you, “Ooh, there is another chemical in the air, like water.” If I say, “Ooh, the yellow is not as bright as it should be…” But it’s always a specific yellow, it’s not the whole yellow, because this energy that hits a molecule is a very specific wavelength, a very specific sub color.
Lisa: By looking which of the sub colors are basically not enough, the light’s not enough, there should be more, that tells me which molecule it hit or which atom it hit. I know because I can do this in the lab. I can have a gas, I shine the light onto it, and I measure what comes out on the other side, thus I have a template to know, “Ooh, this light yellow isn’t there, so it’s this chemical.”
Alan: So this is kind of an obvious question, you don’t have to do this on the fly. You have a machine that reads the color. Is that right?
Lisa: Absolutely. So the light comes in, and it goes over something like a prism. So then you say, “Okay, so what are the intensity levels of the different colors?” And that gets printed on the computer, and then you can see, “Ooh, so this is missing.” It flags what is missing, and that tells you, “Ooh, at this wavelength, that is this chemical.”
Alan: You know, as we talk, I hear one of the hallmarks of your style, which is you… what sounds like totally sincere enthusiasm. You really are lit up by this. When did that start? Did you go through a love of space the way most kids do and never leave it?
Lisa: Well, for me-
Alan: How did it happen?
Lisa: For me, it’s, I think, a little bit untraditional in a way that I was always curious about the whole… everything, kind of everything. I think kids are right, but I kind of luckily never lost that, and my parents also really like… I have loads of books and stuff, but I always wanted to know how things work, and I think most scientists do. And then when I started to study, I actually started to study different kinds of things because I wanted to know this and this and this. So at that time, they found the first planet around another Sun-like star.
Lisa: I was like, “Wow, this is interesting. So you’re telling me that we live in the time where we’re finding whole new worlds orbiting other stars?” I’m from a really tiny town, about a thousand people, in Austria, a very tiny country in Europe. So I was like, “Well, that’s definitely not something I can help with,” because I’d never seen anyone like me doing this. And then I went to a conference. As a student, you do go to one of these conferences and listen, and everybody was super open and nice and they were like, “How are we really need people to help us do this?” And I was like, “Me, me, me, me.” [inaudible 00:35:02]. Oh yeah, great.
Lisa: So, in a way, I think if there’s one thing that the listeners will take from this, it’s like, yep, just ask. Sometimes a lot of times people will think, “Oh yeah, we can use the help.” And then if you say, “Me, me, me, me, me,” maybe they’ll take you and you can work on something super exciting.
Alan: What are you formally? You’re an astrophysicist now?
Lisa: I’m an astrophysicist, yes. It depends a little bit who you talk to. An astrophysicist is when you do want to sleep on the plane, astronomer is when you really want to talk a lot. If you say you’re searching for life in the Universe, then it’s usually never boring.
Alan: How were you prepared to become an astrophysicist? Were you still searching for other interests in physics or biology? What were you studying first?
Lisa: Absolutely. So I started to study physics as an engineer. So I worked on some of the designs for the spacecrafts as well, astronomy as a scientist, so basically learning about the whole Universe. And then what I also really liked were languages. So basically, I studied Spanish as a translator and I studied Japanese because it just sounded really cool that you have-
Alan: And it’s so close to Spanish.
Lisa: I know, right? I just like the fascinating thing about seeing some signs that you don’t know what they stand for, the Japanese alphabet, and then all of a sudden it becomes a picture and you understand what’s going on, which is really, really interesting. And so-
Alan: So you can write in Japanese as well.
Lisa: I would say not anymore. There was a time when I could, but… But I think this whole curiosity is kind of something and trying to communicate with people, that’s, I would say, the different languages, is something that’s always been fascinating to me. So I get to now actually combine it. Because if you want to understand the planet, you have to understand how the star next to it works, you have to understand what the climate is like, could it be warm enough or water or not? You have to figure out if there could be [inaudible 00:37:09], biology, like some kind of life form that could live there. How that, again, would interact with the air, with the chemistry.
Lisa: So I think a lot of people are really interested in these puzzles, or I am really interested in how things fit together and how lots of different puzzle pieces make a super interesting whole that you’ve never seen before, a whole puzzle that is this new world. So in a way, I think curiosity is what got me here. Looking at the world, always, we’ve all been curious eyes, and I think that’s how you see the world too at least from everything I hear.
Alan: I do. When you were talking about being curious about how things work, that’s how I felt as a little boy as well. I’m struck by the idea that you’re interested in finding other life, and you also seem interested in communicating with it, and you’ve already begun communicating with the farthest reaches of life on this planet, learning all these different languages. I share that with you too. To me, I want to learn every language I can, at least up to the point that I can make somebody laugh in their own language, which-
Lisa: I just think that’s a great point.
Alan: It isn’t too hard the way I speak. [crosstalk 00:38:26].
Lisa: As we said before, the good thing is you still have your hand and feet and mimic, so that language point is actually sometimes a lot closer than people think, because if you have hands, feet and [inaudible 00:38:37] plus a couple of good words, then you can make people laugh pretty fast in their language.
Alan: I know. For instance, in China, one of the first things I learned was [foreign language 00:38:47], which is, I’m a very big movie star.
Lisa: See, you have the perfect thing.
Alan: See, I can even make you laugh at that.
Lisa: I love the accent.
Alan: Do you speak Chinese too?
Lisa: No, not at all. That sounded like a good reply.
MUSIC BRIDGE

Alan: Are you the director of The Carl Sagan Institute?
Lisa: Absolutely. So when I came to Cornell, one of the questions that I got from the university was like, “What can we do for you to really consider our offer?” So that’s a great question to get. I was like, “Well, if you’re looking for life in the Universe, I think you really need to bring people from different fields together; from chemistry, from biology, from astronomy, from engineering, to create this forensic toolkit to really find life out there.” And then of course their response, what I could have thought about is that they said, “Well, if you think we should have that, you should come and lead it.” So, voila, I became the founding director of The Carl Sagan Institute here at Cornell.
Alan: You founded it. Did you ever meet Carl Sagan?
Lisa: I actually never met Carl Sagan. I met Ann Druyan, so his late wife, or his wife, widow. Sorry. Yeah. I met Ann Druyan, who is his widow. She’s amazing. So she tells me lots of stories. She’s just this amazing person. When she saw what we were trying to do… We were trying to get this off the ground with lots of enthusiasm, not that much money, of course, as always. But we wanted to do something, and she saw what we were trying to do and she said, “You know what Lisa, if Carl were alive, this is where he’d want to be and this is what he’d wanted to be doing.” So she gave us the name. So that’s how my Pale Blue Dot Institute became The Carl Sagan Institute here at Cornell.
Alan: Oh great. So what’s the work of The Carl Sagan Institute? What’s the mission?
Lisa: So the mission is to find life in the Universe, in our solar system and outside and to create these tools, I call it a forensic toolkit, but basically to create the means to find life if it’s there, especially by looking at a little bit more outside of the box than is normal, by having ideas that come from people from many different scientific disciplines talking with each other. One of the tools, for example, is to basically look at life in as many forums as we can and say, “Well, if the planet were just a little bit different than ours, then maybe one of the life forms that we have here on Earth but never think about could actually be one of the dominant life forms. How would that appear in my telescope?”
Lisa: One of the things I really like about this is when you walk, for example, through Yellowstone, you see these gorgeous, beautiful colors. That’s all different kinds of biotas that are happily living at hot sulfuric acids, but that are happily living in hot temperatures in these different places. I think [crosstalk 00:41:56]. In vents. Thank you. So when you walk, for example, through Yellowstone, you see all these different beautiful colors. That is life, that is different kind of biota that just lives on a different conditions than you and me. Other planets could be like that. They could be hot, they could be a lot of sulfur up like in Yellowstone.
Lisa: So we already know life forms that could happily live there, even so they’re not you and me. So what we’re trying to do is make a color catalog of life that basically documents as much different life forms as we can and how they would look like in our telescopes to not miss signs of life if they are out there, and this is one piece of the puzzle.
Alan: Sounds, from this conversation, that the odds are very great that by the time you find intelligent life on another planet, it’ll be a whole population of very big smart tardigrades.
Lisa: That would be really interesting, because I think they’d have something to say about us landing some of the tardigrades on the moon.
Alan: Yeah, right. What are you thinking of?
Lisa: What are you thinking of? What did you guys do?
Alan: But speaking about flying to the moon, what about the idea that [inaudible 00:43:08] proposed a few times, that there… these are easily the building blocks of life or some form of life itself that’s spraying throughout the Universe, traveling interstellarly?
Lisa: Absolutely. I think of the… That idea is very old, and it has a lot of great appeal because you’d think, “Oh, maybe I’m not from here. Maybe I’m from some exotic other location, another star, another planet.” But if you just look at our own solar system, the Earth had the longest time with liquid water, what we think you need for the emergence of life. So most likely, life actually started here in our own planet. And then if something hits our planet and pushes a part of it out, yes, maybe in the inner part of that piece that now flies through the solar system, there could be some life, and then maybe it hits one of the other planets.
Lisa: But sometimes it’s just so hard to imagine the scale of the Universe, because if we go back to the cookie… and hopefully you’ll always think about astronomy now, and science, when you eat a cookie, that was the whole deal. Then you have two football fields away is the next star. So sport now is forever linked with science too. That’s another key thing. But there’s a huge amount of empty space. So to hit something from this piece that flew off from the Earth to hit something in our solar system is really hard just probability wise because there’s show much empty space. But to hit something in another solar system…
Lisa: So you went through all this cosmic football field distances and then he hit something in this other cookie over there, we’re in the same scale, that is just so, so, so hard that I think chances are that life evolves where you’ll find it, and I think that’s great because Genesis or the start of life on many, many different worlds, on many different moons, on many different planets is going to give us much more of a diversity of life and so much more interesting things to look for.
Alan: This has been such a good conversation for me. We have to continue it another time. We need to stop now. But I want to hear more and I want to keep track of your work because you’ve got… you’re on a path that really is fascinating. There’s probably no one who hasn’t looked up at the stars and said, “I wonder if we’re alone.” You’re working on an answer to that. That’s so great.
Lisa: I think one of the things that I want out of my life, I want to be able to walk out and have a picnic under the stars and actually point to that star over there, that star you see in the night sky and say, “Look over there. Maybe there, is somebody who’s looking up right now too and wondering whether or not they’re alone.”
Alan: This is great. We always end our show with seven quick questions that are just a little bit related to communication. Are you game?
Lisa: Yeah, of course.
Alan: They’re not obtrusive or intrusive. This is an interesting question to come after our conversation, but it might be… you might have a surprising answer. What do you wish you really understood?
Lisa: Life.
Alan: Life. Well, that would answer a lot of questions, wouldn’t it? What is it?
Lisa: It is also a good thing if you say life, it could mean anything, right? Your life, how to do life, how to ow to communicate, how to find life somewhere else. It’s a good one. [inaudible 00:46:59].
Alan: It really brings up the question of when you think you found life on another planet or hope to, what are your standards? What constitutes life?
Lisa: Absolutely. One of the big things is that if you were to find life on another planet, you’d have to be very sure that you have no other explanation for it. Carl Sagan, I think, said it best, “Extraordinary things that you find need extraordinary evidence.”
Alan: Right.
Lisa: Iron clad wouldn’t be another word for it, so no other explanation I can come up with. All my scientific training and all the most criticism in the world, I cannot come up with another explanation. That’s what I’m looking for.
Alan: Okay. Here’s the next question. How do you tell someone they have their facts wrong?
Lisa: Straight out. I think you have your facts wrong.
Alan: That’s pretty straight. That’s good.
Lisa: And then you go from there and see the expression on their face and see where you go from there.
Alan: You’d see red cheeks. What’s the strangest question anyone’s ever asked you?
Lisa: I don’t even remember. I have no idea. Oh yeah. So one of the strangest questions I ever got is like, “So really, you are a scientist? I always expected them to look very differently.”
Alan: Unfortunately, that’s not so strange, that question.
Lisa: But I think personally, this is one of the really strange questions where you’re like, “Okay.”
Alan: Yeah, I hear it too often from women scientists. The stereotype proceeds them.
Lisa: It was actually very funny, because I was giving a talk in the church. So in Germany, we did the lunchtime talk at the church, and the priest meant it like completely non offensive. He was just super excited to see somebody who didn’t look like the textbook version, but he was like, “Are you sure?” I’m like, “Yeah, I’m pretty sure am a scientist.” And I was like, “Is the answer to this one thank you?” Because if it’s not, the stereotype…
Alan: Yeah, that’s probably the safe edge to get on with it. Right. So how do you stop a compulsive talker?
Lisa: How do you stop a compulsive talker? Do you have a good answer?
Alan: No, I asked you first.
Lisa: I think worst case scenario, is just like, you have to go. But I have never figured that one out. Oh no, no, no. There’s actually a good one. That’s a good one.
Alan: Oh what? What?
Lisa: You just say, I’m a physicist.
Alan: And then they have to go.
Lisa: Usually, you never ever mention to you’re an astronomer and hobble is nothing you ever heard of, but if you’re a physicist, some people take that very serious.
Alan: I know psychiatrists who have the same problem. They say, “Oh, I work with people.” You just say, “I’m a psychiatrist.” He’s like, “Oh yeah, what am I thinking?” [crosstalk 00:50:16].
Lisa: Well, I think the problem is if you say you’re a psychiatrist, they try to say, “Ooh, I had this thing. What do you think this is?” So physicist, is usually a safer.
Alan: Or I have a friend. Nobody ever says I have a friend. Where is the nearest star?
Lisa: Yes. That’s true.
Alan: Now, let’s say you’re at a dinner party sitting next to someone you don’t know. How do you start up a real conversation?
Lisa: Do I know anything about that person?
Alan: No, you just met.
Lisa: What are you most interested in? And go from there. I usually am curious about all the answers and I like people, so trying to figure out what people are interested in and why and learning something from that conversation is what I love to do.
Alan: Okay. The person says, “I’m interested in golf.” Where do you go from there?
Lisa: What is interesting in golf? Is it the one walking? Do you have different kind of clubs or swings and-
Alan: Good, good, good, good. You can actually do it with that.
Lisa: I think the interesting thing is if you know nothing about the topic, it’s even easier [crosstalk 00:51:19].
Alan: Okay. Next to last question, what gives you confidence?
Lisa: What gives me confidence? Just generally or in work or in… Sorry, this is a scientist asking a follow up question. What gives me confidence? People.
Alan: People-
Lisa: People, friends, family.
Alan: How do they do that?
Lisa: By being a network, by being people who care, by worrying about me, by caring about me, by asking if everything’s all right. So that gives me confidence in the human species and that we’re hopefully going to survive in the long run too.
Alan: Okay. Last question. What book changed your life?
Lisa: A couple. I think one is Science Like a Candle in the Dark, a Demon-Haunted world by Carl Sagan. I think his clear prose on how the different… how science can cut through some of the biggest confusions in the 20th or 21st century, it’s pretty timeless, is something that still sticks with me, in that I use a lot in class and that I use a lot in life. It shows the beauty of our world. It shows that you don’t have to sacrifice scientific knowledge or curiosity, or the curiosity to getting answers to live in a world that is even more beautiful than anything you could imagine if you would just want to stay ignorant.
Alan: That’s great. Lisa, I loved talking with you. Thanks so much for coming in today.
Lisa: Thanks so much for having me.
Alan: I really enjoyed it. See you soon, I hope.
Lisa: Thank you very much. I’m looking forward to it. Thanks, Alan.
Alan: Bye-bye. Bye-bye.
End Credits:
Lisa Kaltenegger is the Director of the Carl Sagan Institute at Cornell where she explores new worlds orbiting other stars and is a leading world expert in modeling potentially habitable worlds. Because of her research and impact on space exploration, Dr. Kaltenegger may be the first guest on Clear+Vivid to have an asteroid named after her. So, if you’re searching the skies tonight– look for Asteroid Kaltenegger7734 .
Some of you might also recognize her from the IMAX 3D movie “The Search for Life in Space” or heard her speak at Aspen Ideas Festival, TED Youth, and the World Science Festival. Her first book “Are we alone in the universe?” has been published in German and Italian.
For more information about Dr. Lisa Kaltenegger and her work you can visit the Carl Sagan Institute online at: carlsaganinstitute.org