The Sky Is Calling

On February 14, 2017, Jim Edwards spoke with Jack Hitt as part of the ongoing series “Amateur Hour,” in which various tinkerers, zealots, and collectors discuss their obsessions. Edwards is a retired aerospace engineer with a passionate interest in astronomy and space exploration. His home observatory in Redondo Beach, California, is designated U73 by the Minor Planet Center for his collection of asteroid data. Edwards has recently been collecting data on the exoplanet WASP-33b. The conversation that follows has been edited for brevity and meaning.

Jack Hitt: So, you’ve come up with an unusual way for us to identify extraterrestrials trying to communicate with us. A shortcut, really. We’ve been doing this for years. The Search for Extraterrestrial Intelligence—the SETI project—began in 1960. How does what you suggest differ? 

Jim Edwards: The classical SETI approach is to use a radio telescope and aim it at a star and listen to all the different frequencies. So it’s like having a big super-wideband radio and listening to different channels all at once. And you have computers that try to sort out an artificial signal from those being generated by natural processes. These guys pick up interesting stuff all the time, but the problem is that humans are constantly and inadvertently sneaking into the signal. So the machines have to be very smart. They have a bunch of rules in order to say, “This is from some other civilization.” So far, nothing has passed that test yet. 

But they’re largely listening to radio frequencies. You could use this same approach with the light spectrum, but doing it that way is beyond the cost capability of most institutions. And it’s really not a very smart way to do it since there are a near infinite number of light frequencies that would have to be monitored.

So, traditionally, we have been looking for a needle in a haystack. Millions of haystacks actually. 

Exactly. With millions of haystacks, how do you narrow it down? Even when you narrow it down, you’ve still got a lot of stuff to look at.

How many potential exoplanets—planets orbiting other stars—are there? 

In our galaxy alone, they recently increased the estimate to about 400 billion stars. And it’s looking like on average most of the stars have planets of one kind or another orbiting them. Whether they’re terrestrial planets and whether they’re in the Goldilocks zone, which is where life as we know it might exist, that’s a different thing. But just in our galaxy alone we’re talking billions of planets that could potentially harbor life, and so how come we haven’t seen communicative extraterrestrials yet? That’s the Fermi Paradox.

Tell me about it.

Life arose here on Earth very quickly. Admittedly, intelligent life took a little longer. In fact, it’s only existed here for a few tens of thousands of years. But if there are literally billions of planets that have been around for billions of years and are in the same situation, then surely someone should have already gotten to where we are before now. But we have found no evidence, despite the apparently overwhelming odds that we should have. That’s the paradox.

Right. Those are the odds that came out of that formula—what’s it called? 

The Drake Equation. It calculates the odds that intelligent life might exist elsewhere in the universe. Depending on which version of that you look at, there are seven or eight different terms in this equation—say, the rate of star formation (R), the fraction of stars that form planets (f_p), the percentage of those with the right environment (n_e), and so on until you get a formula that looks like this: 

N = R* • f_p • n_e • f_l • f_i • f_c • L

And of those seven or eight terms, we’ve gotten better and better at refining what we think these values are. The harder parts, of course, are those terms relating to life: We only have one data point, really, which is our own Earth and its evolutionary history. Things like: What’s the likelihood of there being any kind of life whatsoever? What’s the likelihood of that life becoming intelligent? What’s the likelihood of intelligent life wanting to communicate with others? Those are numbers that are a little bit more speculative. Maybe we’re unusual in that we want to communicate with others, and maybe for whatever reason the aliens are completely uninterested in communicating with others. But we’re hoping there are others that are like us. We only need one other civilization that wants to talk. But so far we don’t even have that. So that’s the big mystery: We only need one and yet we still don’t have it. 

It’s frustrating. Still, let’s presume that somewhere there are intelligent beings, at least as intelligent as us, that want to talk. 

That’s how you begin to get around that frustration—start with this idea that there must be aliens at least as smart as we are.

Exactly. But we know these extraterrestrials can’t be too far beyond us technically, because if they were then we would’ve already known about them. I mean, you could just look up in the sky and see the blinking light. So they’re not god-like in that I’m picking up transmissions from their world on my car radio. Obviously they’re not sending out these enormous signals. They live in the same universe we do, where energy dissipates quickly over distance. I presume they have the same problems that we do. And so I think, If they had the technology comparable to ours, what would they do? Or, what can we do? Can we come up with something that would be able to transmit to another star in an intelligible way—and the answer is yes. 

Wouldn’t transmitting anything across the galaxy cost a fortune? 

Certainly it would take the resources of either a small nation or a corporation or a university, because it would be expensive to make the signaling device. It’s beyond the means of one person, unless you’re Bill Gates or someone like that, but it’s certainly within the realm of a corporation or university or a nation or a city. If we can do it then the other guys can do it, too. 

So is this signal a message?

When anyone is sending out a blind signal hoping to catch someone’s attention, you first just fire up a flare. No intelligible message, just a recognizable signal that indicates nothing more than this: We are here. 

How in a massive galaxy brimming with super-bright suns can we see anything as feeble as a flare? 

There are several layered aspects to my method, and among the most important is this: How does an alien culture indicate to us that among these millions of haystacks, there’s one with a needle, and then point to that needle? Here’s how we might do it for them and, correspondingly, how they could do it for us. Every time an exoplanet in another star system passes in front of its sun, from our perspective, a small bit of that star’s light gets blocked by the planet, resulting in a very slight but measurable and consistent dimming of that sun’s light.

Right. That’s how we find many of these exoplanets—because their orbit takes them in front of their stars and we can detect that slight dip in sunlight power. When you plot that on a graph, what does that transit look like? 

What you normally see when the exoplanet is not passing between its star and us is the brightness of the star as a straight line across a time graph. A straight line with some fluctuations, but more or less a straight line. 

But if you look at a star when a transit is taking place—where you have a large exoplanet, something like one of our gas giants, passing between us and the star—then what you’ll see is its normal everyday brightness, and then you’ll see it diminish over a reasonably short amount of time as the planet edges into the space between us and the star. What you see on the time graph is that the brightness diminishes. Then it will bottom out, which means the light level becomes constant again, at a slightly diminished level, and that’s the part where the whole planet is in front of the star. Of course, the exoplanet is much smaller than the star, so it’s just a little black dot passing across the star’s face. Then, as the planet reaches the opposite edge of the star’s disk and exits from in front of it, the star’s brightness level is going to get brighter again and go back to normal. So, on paper, it basically just looks like a little shallow dish. 

They call that a bucket graph, right? Because it looks like a small container: ___-——/___

And for the longest time, even recording one of these transits was beyond the capability of amateurs. The invention of CCD imaging and some other related new technologies was what made this all possible.

And it’s why we’ve had this sort of renaissance of discovering exoplanets, right?

Exactly. Because this technology has become available and generally affordable and now anybody can do it. You have to pay attention to what you’re doing and do it right, but it’s within reach of just about anybody who wants to be able to detect some of these brighter exoplanet transits. The professional telescopes, those that are in orbit, like the Kepler, and large, sophisticated ground systems like WASP, can spot much smaller planets than the typical Joe Blow can. Still, we’re certainly capable of seeing many. And amateurs have seen tens if not hundreds of different exoplanets, and even discovered some. 

So what’s the number? How many exoplanets have we discovered at this point, do you think?

I looked that up just the other day and it’s well over 3,000. But that number changes all the time. In February, for example, they announced hundreds of potential new exoplanets. 

Let’s go back to the graphs. Is your argument that extraterrestrials could send us some kind of signal? Using the bottom flat line as a kind of drawing board?

Technically, they could transmit any time they want. And it will certainly be equally as visible at any other time as it is during the transit. The part about the transit that’s important is that it’s the time in synchronization for us to know precisely when to look. This really narrows down the search. We need some natural kind of cues that are more or less obvious to both parties—especially when the two parties have not discussed exactly when or how they will communicate. That’s where the bottom of the dip comes in. It’s a natural occurring, brief, and interesting reference point in time that both we and the transmitting extraterrestrials are very aware of and which can be used as a sort of temporal rendezvous point. And this works despite the fact that we’re separated by many light years and, due to the finite speed of light, potentially decades in time. That’s when I would look, and I’m thinking that they are having similar thoughts, so that might be when they would transmit a beacon using a laser aimed at our sun. 

You recently imaged a certain star and collected some data. Which star was it? Did you detect any alien signals? 

Because of the very modest equipment that I used, I needed a relatively bright star with a largish exoplanet. There are online databases of stars that have known transiting planets. So I just went through the list and looked for one that was very bright and suitable for a proof-of-concept test that I’ve been wanting to do. Then I found this exoplanet called WASP-33b. There are a lot of WASP-designated exoplanets, because it is named after the instrument that discovers these. 

That’s in the constellation Andromeda, which is visible in the night sky just beneath the famous W of Cassiopeia.

Right. So I have to collect two kinds of data. One kind of data has no filtering at all, which means that the camera simply looks through the telescope and takes a picture of the star. It’s basically what your eye would see if it was very sensitive. Those are the easy images. They only take less than fifteen seconds of exposure. The harder images to take are the ones where I use what’s called a narrow-band filter. That means it only lets in light whose bandwidth matches that of the laser being used by the ETs as a beacon to pass through the filter and on to the camera. When you hold this filter up to the night sky you literally can’t see anything through it, it’s almost as if it’s a welder’s goggle. It radically dims the brightness of the star, many orders of magnitude. So instead of capturing an image using a fifteen-second exposure, I have to use one that’s 180 seconds long. That’s twelve times as long, because the light that’s getting through the filter is so much weaker. And longer exposures are just inherently more difficult to do. During the session, I collected three images without the filter, then three photos with the filter inline, then three more photos with it out, going back and forth. That’s what you see in the graph I plotted, my little shallow-dish graph. There are three red dots, three green dots, three red dots, and three green dots. That’s because I was swapping back and forth between the two different filter configurations.

And why are you going back and forth?

Well, I need the clear filter, the one that doesn’t restrict the light at all, to use as my baseline to know what the star is actually doing—what’s happening with the transit. The heavily filtered one is the one that I’m hoping would carry an extraterrestrial signal with it, namely the beacon signal they transmitted using laser light with the same wavelength as my narrow-band filter. So if both sets of images show the same signal—they both show the same transit signature—then that means there was not an extraterrestrial beacon associated with it. And that is what I observed this time, of course. But if the heavily filtered images did show some variations from what I see with the unfiltered images, then that’s when I can say, “Okay, maybe there’s a signal there. That is an extraterrestrial beacon.”

And how would that signal work? When you’re looking at that graph, what are you looking for? 

What you’re looking for is something that is not natural, something that is not what you would normally expect to see in an unmodified transit. The normal transit where there’s nobody transmitting just looks kind of like a shallow flat-bottomed bowl. If they were to use a technique like I’m suggesting—a high-energy laser at a particular frequency—then we’d see that same shape, that same flat-bottomed bowl. But periodically along the bottom of the bowl we would see a sudden pattern, like a Morse code—not something I would normally expect to see. 

But this is not a message of any kind. It’s just a flare. 

And you have to be careful. When pulsars were first discovered, the rotating neutron stars, radio astronomers heard these “beep beep beep beep beep” sounds in the radio stations and they thought, “oop, there’s the Martians,” but it ended up being a purely natural phenomenon. So what you’ve got to do is make sure whatever signal you send out is sufficiently abnormal from something that nature would produce.

A man-made pattern. An intelligent-being pattern. 

If I suddenly saw a transit signal get bright and dark, on and off—that might not be an unusual pattern. It might be due to atmospheric effects of the exoplanet or spots on the star itself. But if you were to see two minutes on and two minutes off then four minutes on and two minutes off then six minutes on and two minutes off then eight minutes on—you know, some irregular pattern that could not be reproduced naturally—then that would be a big giveaway that there’s some intelligence behind it. 

How do you know what light frequency to look at? Didn’t you say there were millions of them?

There are so many different things that have to be coordinated between the two parties that want to communicate. Thinking like them, and assuming they think like us, you have to look for some natural cues, some things that are kind of built-in to the universe. I could pick any frequency but there are some magic frequencies that appear to have special significance. One of them is called the H-alpha line, the hydrogen-alpha line, and it is a specific frequency of light that corresponds to a very important aspect of physics, and it also just happens to roughly line up with the brightest part of a normal sun’s output. So it kind of makes sense. This hydrogen-alpha line is so common that astronomers use it all the time to look at things like nebula. 

And you’re saying that another intelligent life force or form would probably be drawn to the hydrogen-alpha line for the same reason that we are drawn to it?

Exactly. 

So who should be doing this? 

There are a lot of us astronomers, amateur astronomers, who already do collect data on exoplanets. There are hundreds if not thousands across the world who do this stuff all the time, and there are professionals like NASA or university programs that do it as a paid endeavor. That’s where we’re getting these 3,000 candidate-transiting planets in the first places. What’s not being done, as far as I know, is looking at a very specific, narrow frequency during transit. What I like about this idea is that it’s something that’s so relatively simple to do—all I’m saying is that you have to put an affordable, low-tech filter in line with your telescope and look for a very small artificial signal. And the H-alpha filter is probably already in the toolbox of most amateur astronomers. 

What do you think would happen if we actually made contact with an extraterrestrial alien?

The thing a lot of people don’t really appreciate is how slowly this exchange would take place. Because the aliens, they’re light years away. If we say, “Oh, okay, we found your signal. Here we are,” it will take twenty years for them to say, “Oh, here’s something more.” I think that would be just about the most amazing discovery that there is. But how would it change my day-to-day existence? Well, it wouldn’t. Because they’re not coming here and we’re not going there and the rate of communication is so slow that it wouldn’t make any difference over a short time scale. But it would have all sorts of philosophical impacts. God knows what it would do to religion, for example—pun intended. It would make a huge difference as far as our view on our place in the universe goes. 

Tell me about the Encyclopedia Galactica.

Oh, it’s been used in many different science-fiction stories and universes where they talk about the collection of knowledge of all the species in the galaxy. The composite of all the information that we have, all in one place—like the internet of all our knowledge, and we’re sharing it. Let’s say the Neptunians know how to do certain things, but then they learn something new from the Alpha Centaurians, so they add that to the encyclopedia, and then they learn something else from the Hudlarians, and so on. They just send it out there, and we would add our own knowledge to it.

So this would be a way to sort of set up the first hyperlink to another exoplanetary—

For all we know, this stuff is already being transmitted. We just haven’t been looking in the right place or at the right frequency. That’s why the beacons are so important. That’s how they tell us: Here is the place that’s got the information. Once you know where to look, the beacon is just the start. That’s just the “hello” and then you can start this full conversation. 

That would be remarkable. We just have to find it.

I often think, well, is there some advanced technology that we don’t have? Maybe there is. Maybe once we discover this advanced-communication technology we will turn it on for the first time and find out that there’s a whole cable system worth of signals from all these different civilizations and it’s just that we didn’t have that technology yet. So, that being said, you might ask what’s the next best thing? Well, this is the next best thing. Communicating between stars is difficult because they’re so far apart and you have to be clever and think of the ways to most efficiently communicate and what to look for. Because this is the universe we live in. Not the one we want to live in, but the one we’re stuck with.

So you have to go searching for extraterrestrials with the universe you have, not the universe you might want.

Exactly. Until we know enough to make our own universe.