If aliens are trying to talk to us (or even if they are not), Jill Tarter will be the one to find them. She cofounded the SETI institute in 1984 and ran its research center for many years. She was also the inspiration for Jodie Foster’s character in the 1997 movie Contact. Astrophysicist Maggie Turnbull, who is currently running for governor of Wisconsin, began working with Tarter in the late ’90s and is now affiliated with the SETI Institute. She’s currently working on a NASA telescope called WFIRST, set for space launch in 2025.
The two scientists don't search for extraterrestrial life in the same way. Tarter has focused on finding evidence of advanced alien technology, while Turnbull looks for biological signatures. We sat down to talk to them at the Wired 25 festival in San Francisco in October. While they may be pursuing different aims, they’re both aligned on one important thing: The quest to find life outside our planet could bring us all together.
(This interview has been condensed and clarified.)
WIRED: What are the characteristics that make a system potentially habitable when you’re deciding what to look for?
Turnbull: One is longevity. The brightest stars burn through their fuel the fastest, and they will be done burning through their hydrogen reserves and swelling up into red giants before they're even done forming planets. So those kinds of stars? Not on the target list. Also, if a star does not contain any heavy metals, assuming the planets form out of the same material that the star is formed out of, there is a lower probability that there are planets in that system. So very metal-poor: also bad.
WIRED: There is sort of a bifurcation in space research between looking for biological signatures of life and looking for technological signatures. Can you define what both of those are?
Tarter: SETI is about the search for extraterrestrial intelligence, though we had no way of understanding how to detect intelligence directly. So we took technology as our proxy and said, “Is there some technology out there that's modifying its environment in ways that we can manage to detect over interstellar distances? If we can find some kind of technological clue, then we'll presume that at some point there were intelligent technologists that created it.”
On this planet, bacteria dominate. Microbial life is much more prolific than complex life, and perhaps it will be that way elsewhere. So we should expect to be able to find the microbes perhaps before we find the complex life.
WIRED: But now the fields are coming back together a little bit?
Tarter: Historically we've been looking for signals in the electromagnetic spectrum. That's what SETI has done. More recently, considering the new ground-based telescopes that we're building and the new space-based telescopes that we're building, we begin to think, “How can we use those to find something that only a technology could do?”
Signals is still a good idea, but there may be many other things that, with these new observational characteristics, we can find. And so the astrobiology community was sort of schizophrenic for a while, and it was OK to look for microbes through kind of the beginning of complex life. But they said, “Nah, SETI, that's not part of astrobiology.” But we've just now seen a revisit of that, as the astronomers prepare for the next decadal review where we all sit down and prioritize what we want to do for the next decade. And a National Academy of Sciences committee looked at an astrobiology strategy, and they are far more willing to level playing the field, to accept the idea that both technosignatures and biosignatures belong under a large umbrella of astrobiology observations.
WIRED: What are your favorite examples of possible alien technology that is potentially detectable by our instruments?
Tarter: There is this fabulous star system or planetary system called Trappist-1. Seven planets orbiting a tiny dwarf star. They're very closely packed; all of their orbits would fit inside the orbit of Mercury if they were in our solar system. And three of them are perhaps at the right distance from their star so that if they had an atmosphere they could have liquid water. All right so now take those seven planets at different distances from their star. And say when we get an opportunity to actually explore them we find out they're all the same. They aren't different temperatures. They actually all look identical. Well that's not likely, given nature, but if some technological civilization arose on one of them and decided they wanted more real estate they might in fact transform all the other planets in their system to be the same.
WIRED: Maggie, tell us about the telescope you're working on and what that can detect.
Turnbull: Right now my biggest project my biggest and most overwhelming project is with the WFIRST telescope. (As we get closer to launch it will get a more fun name than that.) But it means the Wide Field Infrared Space Telescope; most of the observatory is designed for deep sky work and looking at dark energy and dark matter. Two of the sexiest topics in astrophysics … but the first sexiest topic in astrophysics is definitely exoplanets and life. So, as a technology demonstration, we're including the first ever space-born camera to directly take pictures of the nearest planetary systems. That’s never been done before.
What we're going to do is start with a few of the planetary systems that we know for sure exist. We've detected them through the gravitational pull that those planets have on their star. We've never seen them directly, but we know for sure they're there.
WIRED: What will you look for?
Turnbull: Water in the atmosphere has very very strong absorption feature. Plants have a very distinct signature because they're very dark. We think of them as being green because they reflect a little bit of green light. But for the most part, they are very dark because they're absorbing all of that light and using it as the energy source to build their bodies. Then they get really reflective in the infrared and there's a lot of theories as to why this might be. Maybe it's a cooling mechanism—whatever the point is, it's really visible. The vegetation is very visible and it's been a signal being broadcast in reflected sunlight to the universe for the last billion years. So that's something that we could potentially see for an Earth-like planet.
WIRED: Maggie you're also running for governor of Wisconsin.
Turnbull: I almost forgot!
WIRED: Tell us about that decision.
Turnbull: There's so much going on environmentally and with science education and our policies with managing our natural resources that are not being informed by science right now that I just felt like somebody has to step up. I'm running as an independent. I really thought about the two party system and how that's been affecting us socially and culturally especially in Wisconsin. It's very divided. It's really vicious and it's very insidery. And the only way to get a woman on that ticket, the only way to get a scientist on that ticket was to go independent. I may not have a snowball's chance in hell of winning that but at least we're getting topics on the table for discussion. Like ranked choice voting. Automatic voter registration. Voting rights is a really big issue for me mainly because that is what's underneath all these other issues like having roads, making good decisions about our roads and our schools and our natural resources and our health care. All of that stuff requires consensus. Otherwise we're just on this pendulum going back and forth between red and blue and always undoing what we did four years earlier.
WIRED: That gets me thinking about the role of the public in SETI research.
Tarter: If I look out in the audience how many people have run SETI@home on your computers. [Many raise their hands.] It's been around now for more than a dozen years, and I think it is the thing that put distributed computing and citizen science on the table. SETI didn't invent distributed computing. People had been using it to factor Mersenne primes and to break codes for a while, but then this SETI@Home application came up and it went wild. People loved the fact that they could use their computer to look through stored data and perhaps find a signal.
WIRED: What would that look like if someone found a signal?
Tarter: Their computer would report back certain parameters that they had detected. At UC Berkeley, where this is being run, they would put that into a great big filter along with everybody else's reports and they would start to build a case of whether this signal actually appears to be coming from a single point on the sky and move the way the stars do. They build a candidate list of the top 10 or 20 or 100 signals and they request time to go back to the telescope and specifically re-observe at each of these places.
Getting people involved with SETI is incredibly important for another reason: It gives us an opportunity to change everyone's point of view. It’s like holding up a mirror and saying, "See all you all you down there on Earth you're all the same when compared to something else that might be out there." And by building a global network to solve and work on this problem I think it's a good model for dealing with the other challenges that we have on this planet, challenges that don't respect national boundaries but that have to be addressed systemically and we're not good at that at all.
Trivializing the differences among us is one of the best things that SETI can do and the reason that we want to involve the world.
WIRED: Astronomers would tell you that there are hundreds of billions galaxies each containing hundreds of billions of stars, or whatever. So surely mathematically, statistically, there’s a huge number of planets out there that support life. But then you have people who say life had to emerge on Earth through a very specific series of events, and the possibility of that happening again is infinitesimally small. Are you ever discouraged having devoted your careers to looking for something that you might never find?
Turnbull: No. I love when everything is wide open. There are really strong arguments for both possible answers. And I think that as a scientist you have to get comfortable with sort of being of two possible mindsets at the same time. It's like a quantum state that hasn't been collapsed yet where you can simultaneously imagine, “There's no way that's happened more than one time,” and, "It has to be everywhere!"
I think this has to be just about the most vibrant scientific field on the planet right now. It's so multi-disciplinary. There are so many different lines of evidence and inquiry that play into the search for life.
Tarter: When I was a young scientist, Philip Morrison, one of the founders of the SETI effort, said to me, "Any subject in which the error bars are in the exponents, so that we don't know within factors of ten or a hundred or a million, that's not a theoretical science, that's a science that's going to make progress due to observations."
And if you say, “OK, the right thing to look for is electromagnetic signals,” now there are nine different variables that could describe such a signal. So you have a nine-dimensional search space. So take that search space volume and set the volume equal to the Earth's oceans. How much have we searched? Well when I did that calculation a decade ago I came up with one glass of water out of all the Earth's oceans. And last week some students of Jason Wright at Penn State published a reexamination of that, and they say that now it's more like a hot tub or a small swimming pool. There's a lot yet to go. We've hardly begun to search, it may not even be electromagnetic signals—it may be something else.
WIRED: In the movie Contact, Jodie Foster's character does detect alien civilizations. When she's being interviewed for the job of going to visit the aliens, she's asked what her one question for them would be. What would you ask them?
Tarter: I have to admit a bias, because I was part of that conversation with Carl [Sagan], and the question for me would be, "How did you do it? How did you manage to get through the technological adolescent phase that we Earth are in today to become an old sustained technological civilization?”
Turnbull: I would probably just ask, "How many, how many of us are there?"
WIRED: Now I think we have some time for audience questions.
AUDIENCE: The Fermi Paradox says that if there were so many habitable planets, we probably would have gotten some evidence of it so far. But we haven't. Because maybe the way in which they reach out is when they just want to destroy you. And Stephen Hawking had said the search for extraterrestrial intelligence was a bad idea, because if they come here, they colonize us like Columbus colonized the new world. So what are your thoughts on that?
Turnbull: I don't know if we appreciate just how far apart the stars really are. Even those of us who study the stars—I don't know if we really absorb how challenging it is to actually travel to other star systems and how, energetically, what that means to survive a trip like that. So for a civilization to actually travel between the stars, there is so much internal collaboration and cooperation and stability that is required that you have to basically be evolved to the point where you really are a peaceful civilization or you will self-destruct. So the fact that we haven't heard or been visited to our knowledge isn't necessarily because they're not around. It could very well be that they are peaceful people who know when it's the right time for something like that.
Tarter: If you were asking the question “Are there any fish in the ocean,” and the experiment you did was to dip one glass of water out of the oceans and look and didn't find any fish, I don't think you should conclude that there weren't any fish.
And that's what the Fermi paradox requires you to conclude. We just haven't searched enough to be able to say whether or not they're out there. And then Maggie has stolen my favorite argument against Hawking, which is that it's hard to become an old, long-lived technological civilization without outgrowing the aggression that probably made you intelligent in the first place. So if they can get here I honestly don't think that we have anything to worry about.
AUDIENCE: What happens when you look within our solar system and what kinds of signatures and what kind of information do you get within our solar system.
Tarter: We have begun to spend a little time doing some radar studies of the Lagrangian points. We've had a lot of folks suggesting that asteroids might be a good place to place an artifact and we're going to be visiting these worlds. And so that's a part of the techno signature. Let's keep our mind open for what we could we could find, and let's try and figure out what what's at the Lagrange L4 and L5 points. What are those Kordylewski clouds?
WIRED: Jill can you tell the audience what we were talking backstage about some mysterious signals.
Tarter: We have this mystery in the radio astronomy field about what fast radio bursts are. FRBs. We think that there may be as many as 10,000 of them going off in the sky every day. They last for a millisecond or less and we don't know what they are.
Maybe these FRBs are just the transportation worm holes opening and closing around the sky. That was my idea for a sequel to Contact. But FRBs are a real mystery, and we're trying to build instrumentation that can better illuminate what they are.
AUDIENCE: Do you guys have favorite science fiction?
Turnbull: It’s so cliche. I just, I love Star Trek. Especially The Next Generation. I just watch those over and over again.
Tarter: And Janeway!
Turnbull: And Janeway! I love Janeway. What's yours?
Tarter: Arthur Clark and Azimov, those were the books that I grew up with.
AUDIENCE: Similar to the space program, do any of things that you are creating have applications not out there but here?
Tarter: Some of the algorithms that we are using for real-time signal detection have applications other places. Long ago we were looking at a particular type of transform called a radon transform that actually turned out to be a really good way of detecting microcalcifications in breast cancer screening and mammograms. It went to a first-stage trial. Turned out it was too expensive, and it did not get put into the commercial domain. But yeah it's finding patterns in noise. There are a lot of different applications for that. And now we're hoping that what's coming out of industry and the university systems, the neural networks, will help us interrogate data without having to ask the computer to find a particular pattern. We’ll let the neural networks tell us if there's something there other than noise.