In Conversation

Contact with aliens by 2036? Astronomer Seth Shostak wants to believe — and does

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The Parkes Radio Telescope at the Parkes Observatory in New South Wales, Australia. Image courtesy of Seth Shostak.

Astrophysicist and astronomer Seth Shostak made a daring bet in his 2012 TED Talk: We’ll find extraterrestrial life within 24 years or he’ll buy you a cup of coffee. This isn’t just wishful thinking — technological advances over the past few decades have amplified the scope of space exploration monumentally, allowing us to search the stars in ways we never have before. We spoke to Seth about his work at the SETI Institute, our cultural fascination with aliens and why he thinks we’re closer than ever to finally finding ET. 

This transcript has been edited for clarity.

What have you been working on lately?

I do a lot of writing, a lot of talking and, of course, the science and speculation: What would be the best strategy to find ET?

We’ve been looking at a list of about 20,000 so-called red dwarf stars. Red dwarves are just stars that are smaller than the sun, and there are a lot of them. Just like there are a lot more small animals than big ones, there are a lot more small stars than big ones. The other thing is that they take a long time to burn through their nuclear fuel, so they live for billions and billions of years, which means that on average they’re older than stars like the sun.


“The bottom line is, the search has become much, much, much faster. If you’re looking for a needle in a haystack, it pays to go through the hay faster.”


With a star, if the planets around it are billions of years older than our own solar system, maybe the chances are greater that they’d cooked up some intelligence and is sending a signal we might pick up. That’s what we’re doing at the moment in terms of our SETI work.

So, how’s the hunt? How much closer are we?

When people say, “Well, so what’s the difference now between what you guys are doing and what Frank Drake — who did the first SETI experiment back in 1960 — did?” the difference is technology and science.

The Parkes Radio Telescope at the Parkes Observatory in New South Wales, Australia. Image courtesy of Seth Shostak.

We can now build receivers that can listen to a lot more radio dials at once. Frank Drake had a receiver that could only listen to one channel at a time, sort of like your TV. We don’t know where ET might be on the dial, and we don’t know where that transmission might be, so we’ve got to really listen to lots of frequencies at once, lots of channels. The receivers we’re using today monitor 72 million channels simultaneously; you can sort of sift through the radio dial for any given star system much more quickly. The bottom line is, the search has become much, much, much faster. If you’re looking for a needle in a haystack, it pays to go through the hay faster.

The other thing that’s changed is the astronomy. When SETI began, nobody knew whether there were planets around other stars, if they were common, or maybe only one star in a thousand had planets. Nobody knew because we hadn’t found them yet. But since that time we have. We’ve found lots of planets, and what we found is that the majority of all stars have planets. Planets are as common as cheap motels. That’s good news because it means you don’t have to wait for somebody to discover planets around some other star and aim your antennas in that direction — we can just take a whole bunch of stars based on other criteria, like here are the 10,000 nearest stars or the nearest 20,000 red dwarf stars. We’re not worried too much about whether the stars have planets or not, because we know most of them will have planets. That’s a big step.

Those are the things that have changed — the technology and the science. Both of those, from my point of view, encourage me to think that we may find something within 20 years.

That’s a really exciting prediction. In your talk, you said that any civilization that we get in contact with or receive signals from will be far more advanced than us. Why haven’t we heard from them yet?

Two things: Maybe they have, and we just haven’t pointed the antennas in the right direction and to the right frequency! That’s the whole premise of SETI — that as we sit and talk, there are radio waves going through your body that would tell you about some Klingons if only you had a big antenna pointed in the right direction and you knew the right spot on the dot.

The other part is that I don’t know that they would be motivated to contact us unless they knew we were here. Maybe it’s an expensive project for them. Like, “Hey, what do you think — should we build a big transmitter and just ping the nearest million stars for 20 years at a time?” You know, that could be a big project. But if they knew that there was intelligent life here on Earth, maybe they would try and get in touch because maybe they want to sell their used cars or something.

The facts are that they probably don’t know that we’re here. How would they know that homo sapiens exist? They could start picking up our radar, television and FM radio — signals that actually go out into space. They could do that beginning in the Second World War when all that technology was developed. But that was only 70 years ago. If they’re more than half that distance — so 35 light years away — there hasn’t been enough time for those signals to get to them and for them to say “Oh, well, we’re going to answer those guys.” That means it’s very unlikely that anybody knows we’re here yet even if they want to find us. Unless they’re very close to us, they won’t succeed. They probably lost their funding and they don’t get any respect at parties.

And by the way, you might like to mention that to your friends, next time they tell you that they’ve been abducted by aliens. You could say, “Well, that’s peculiar. You know the Earth has been here for four and a half billion years, and they just now showed up to abduct you?” I mean, why now? It’s hard to believe that they might be relentlessly targeting our society — they might be, that’s the hope. That they might just have very strong transmitters that you could pick up anywhere nearby. That’s what we’re hoping for.

ʻOumuamua, the first interstellar visitor, has been a source of fascination since it was first discovered in 2017. Some speculate that it could be a sign of extraterrestrial life and last December, SETI, among others, conducted a radio search but didn’t hear anything. What do you think ʻOumuamua is?

It’s become an interesting public issue because Avi Loeb at Harvard likes to talk about these things, that it could be the Klingons and the space crafts. That’s not impossible, but it’s like you hearing a noise from the attic — I mean, it could be ghosts, but that’s probably not the most likely explanation. The other thing is that every time we find something unexplained in the heavens many people — or some people at least — will say it’s alien activity because that’s a handy explanation. It accounts for everything because you can always say “Well, the aliens can do anything, right?” There is that tendency to blame the aliens for everything.

This thing came in and it went right through our solar system, right around the sun. You could say, “All right, it’s just a random rock kicked out of somebody else’s solar system,” but what are the chances that that rock is going to actually hit ours? The chances of that are pretty small. It’s like standing in Park Slope, Brooklyn and throwing a dart up into the air and hitting a particular nickel lying on the sidewalk down by the Brooklyn or Manhattan bridges [ed note: ~3 miles away]. It could happen but it’s pretty unlikely. Unless you throw lots of darts — if you throw a gazillion darts into the air, then you’re probably going to hit that nickel. What Loeb is saying is that either there’s just lots and lots of these rocks cruising this part of the galaxy — which could be, but that seems a little unreasonable — or maybe somebody is deliberately sending them our way. If you’re deliberately aiming at that nickel, then you have a higher chance of hitting it.


Aliens probably don’t know that we’re here. How would they know that homo sapiens exist?”


To say that it can’t be a comet because we didn’t see any evidence of that is subject to criticism based on the fact that we didn’t see much of anything on this thing because it was found very, very late and it’s very small and very far away. We never saw this as more than a dot. There’s no reason at this point to say, “You know what, Bob, no two ways about it — this has got to be artificial!”

It seems hard to draw conclusions because no one can collect any more evidence — ʻOumuamua is on its way out at this point, right? It seems all we can do is speculate at this point.

It’s now somewhere between Mars and Jupiter. You can’t even see it with the biggest telescope anymore. Loeb admits that and says we’ll find more. We’re probably gonna find another one within a year or two, and this time, everybody will be on the alert to start studying it right away and if it’s possible, maybe send a rocket in its direction with a probe.

Has this discovery changed your approach at all?

There’s simply no shortage of intriguing new discoveries all the time. Two or three years ago, it was Tabby’s Star. Jason Wright at Penn State said, “It could be an alien megastructure,” so we turned our antennas in that direction. We didn’t find any evidence of an alien megastructure either. The point of ʻOumuamua is that you have one more case where you find something unusual that could conceivably be aliens. It would be hubris, of course, to sort of weed these things away and say, “It’s not likely to be E.T.” With that kind of reasoning, you’ll never find E.T.! It’s a reminder that the evidence may come out of left field and you shouldn’t dismiss it just because of where it came from.

It’s been almost 60 years now we’ve been pointing the antennas in the directions of nearby stars that may have habitable planets, all the usual stuff. It just seems more and more possible to me that the real thing to do is spend more time looking for other kinds of evidence — not radio signals because they may not be broadcasting radio signals our way. They might be doing all sorts of other things like hollowing out asteroids and sailing them around or building alien megastructures or constructing something big and brawny. They could be building something that’s noisy enough or big enough or bright enough — conspicuous in some way — that you could find it without having to count on them directing some sort of radio transmission our way.


“There is that tendency to blame the aliens for everything.”


Many of your contemporaries are going to come down hard on you when you speculate about something that might or might not be true, as opposed to writing a paper on something that you’ve just measured. When you do that they’re going to say: “Okay, you’re making up stories and you’re just doing it to get the column inches.” And I think that that’s myopic, because it’s those ideas that provoke a lot of investigation and eventually, in many cases, they actually solve the problem.

What is your favorite part of your job?

I enjoy thinking about the possibility of SETI. Because we haven’t found anything, it’s still all possibility. I talked to a film writer who’s writing a screenplay, and he wanted to get the aliens right — whatever that means — what can you say about them? I mean, we haven’t found any, so you can say whatever you want.

I give a lot of talks and I try to give at least one in ten to kids. I like them because they are completely honest. You talk to them and if they don’t find it interesting, they just put their heads down on the desk. Adults will not do that. But if they are interested they’ll ask any question. There’s no such thing as a stupid question for a kid. When you talk to kids, you notice that maybe one in fifty of them, something lights up; they hear something that gets their imaginations going that they’ve never heard before.

What do you think we’re looking for? Why do you think we’re so fascinated with this concept of extraterrestrial life?

I honestly think it’s a hardwired feature, just the way kids are interested in dinosaurs. You’d have a hard time finding kids that aren’t interested in dinosaurs — and why is that? Do they just have a need to know about sauropods? Well, that’s just part of their brain. We’re kind of hardwired to be afraid of falling. That’s undoubtedly a throwback to our simian existence in the trees, climbing around, and if you fell, it was probably the end of you. You have all sorts of mechanisms that tense up and react very quickly if you begin to fall. The same would be true in terms of paying attention to any creatures with big teeth. It probably pays for you to be interested in big teeth and other potential dangers.

I think that’s why kids are interested in dinosaurs, and I think we’re also interested in aliens for pretty much the same reason. Namely that, if you have no interest in whether somebody is living on the other side of that hill outside town, then you’re very likely to someday see them come over the hill and maybe take your land or kill you. It might pay you to pay some attention to potential competitors or, looking on the bright side, potential mates. I think that that’s why we’re all interested in aliens up to a certain age. It’s hard to find somebody who’s not interested in aliens at all.