SETI at 50
We haven’t heard from ET. Is it time to rethink the Search for Extraterrestrial Intelligence?
Written by Science & TechnologyFiled under
Are we alone in the universe? That’s the big question the Search for Extraterrestrial Intelligence (SETI) seeks to answer, and so far the answer appears to be yes. In the half-century since Frank Drake first used a radio telescope to begin searching for alien radio signals, there has been no message from ET—indeed no artificial radio traffic of any description.
SETI researchers argue that SETI has not been a failure, emphasizing that they have searched just a tiny fraction of the available space in the galaxy, and that the project is just getting started. To be sure, the computer revolution has enormously enhanced our ability to 1) search simultaneously over many different wavelengths, and 2) to filter out man-made signals, which theoretically increases the odds of a successful detection event.
But in the forthcoming book “The Eerie Silence” (Houghton Mifflin Harcourt), British-born physicist/cosmologist Paul Davies—director of the Beyond Center for Fundamental Concepts in Science, co-director of the Cosmology Initiative (both at Arizona State University), and chairman of the SETI Post-Detection Taskgroup—argues that SETI scientists ought to broaden their search beyond “traditional SETI” (i.e., radio messages) to include a “search for general signatures of intelligence, wherever they may be imprinted in the physical universe. And that requires the resources of all the sciences, not just radio astronomy,” he writes.
I ventured to the Beyond Center in Tempe, Arizona, to meet with Davies and discuss the themes he explores in “The Eerie Silence.” In the following exchange—the first installment of a two-part Failure Interview—we covered issues like: What has SETI accomplished in 50 years? And what are some of the ways Davies suggests expanding the search?
In the meantime, the folks at the SETI Institute in Mountain View, California, continue to keep champagne on ice round-the-clock, in anticipation of the day scientists discover ET.
Why don’t we start by defining SETI?
Fifty years ago, in a famous pilot experiment [at the U.S. National Radio Astronomy Observatory in Green Bank, West Virginia], Frank Drake first used a radio telescope to see if any messages from an extraterrestrial civilization might be coming our way. Using a radio telescope isn’t the only way one can look for signs of intelligent life elsewhere in the universe, but it’s the most obvious way, because radio telescopes have the power to communicate across interstellar distances. So SETI, as it’s usually interpreted, is this radio telescope search.
What has been accomplished in 50 years?
The title of my book—“An Eerie Silence”—says it all. There has been no definitive message from any civilization or indication of any artificial radio traffic. There have been a few intriguing “don’t knows” [the “Wow” signal, a 72-second pulse detected on August 15, 1977, as well as a half-millisecond blip known as Lorimer’s pulse]—transient events that are difficult to evaluate after-the-fact. But nothing where one can say: If you point your radio telescope to a certain part of the sky you’ll pick up a bleep-bleep from what looks like an artificial source.
However, Drake’s pioneering experiment was done with steam age technology. Since then the computer revolution has enormously increased our ability to search simultaneously over many different wavelengths and to filter out man-made signals. It is no longer necessary for an operator to sit at the controls, steer a dish, and listen on a loudspeaker. It’s all done by computers and astronomers put their feet up.
How do SETI researchers keep from getting discouraged?
They are irrepressible, aren’t they? I think most of them take the point of view that they are doing good astronomy anyway. They are using state-of-the-art equipment and developing algorithms for searching through the signals, which is useful to do anyway. And they can always think that with improvements and more money they eventually will pick something up.
Who pays for SETI research?
It’s almost all paid for by private donations. And the total cost is very modest by the standards of almost any sort of scientific venture. It’s a drop in the ocean compared to what is being spent on other things.
In the book you write about your belief that traditional SETI is stuck in a conceptual rut.
Everyone is still enthralled with Carl Sagan’s vision, his idea being that there is a civilization out there that guesses we’re here, beams a message at us using what in technical jargon is called a narrow-band signal, and all we have to do is tune in and get the message and all sorts of wonderful consequences will ensue. I don’t think that is credible. We need to look for signatures of intelligence wherever we might see them. And when it comes to radio, I think we should refocus to look for beacons, not narrow-band signals. The SETI community is slowly buying into this, but the majority of SETI has been with a narrow-band signal.
How is it that something as bold and visionary as SETI became stuck in a rut?
It is remarkable, isn’t it? But I suppose the difficulty of the task means you have to focus on a particular strategy and then refine it and refine it. There’s always that tendency in science. What you’re good at, what you understand, you do more of the same.
How extensively have SETI researchers searched thus far?
They have looked in a little bubble around our neighborhood, which is why the title of my book irritates the SETI people, who say, “What do you expect? We’ve only been doing it for 50 years.”
But if you’re an optimist and you apply Moore’s Law to this, then within a few decades researchers can probably search the whole galaxy, and then the science will become much more significant. It’s too soon to say it’s a waste of time to carry on with traditional SETI. I think it’s a great thing, but maybe after 50 years the public might be thinking, “Can we try something else?” And I think we should. We should think much more expansively about what a signature of intelligence might be. Forget messages, all we really want to know is: Is anyone out there? Their presence could be betrayed in a large number of ways.
The public seems to assume that alien life, if it exists, would be reminiscent of human life. But biologists have recently discovered microbes living under extreme conditions. What’s to say that intelligent alien life can’t live under extreme conditions?
This is where you’re on a sliding scale of speculation. The first speculation is: Maybe there’s alien life, but it’s life as we know it. Let’s be conservative and assume that life elsewhere would follow the pattern here. It would be carbon-based, require liquid water, would evolve over billions of years, and so on. Then you end up with the familiar features. We could easily speculate about radically different forms of life. Whether radically different forms of life could ever become intelligent is another matter.
And if we encountered alien technology we might not be able to recognize it. There are some who go so far as to say that the entire universe is a product of alien technology, and the reason it all looks so gee-whiz and works so well is because it’s designed to do exactly that. But leaving aside that sort of wild speculation, the difficulty is to know how really advanced technology would manifest itself in a way that would make us sit up and take notice, without us saying, “It’s a miracle!” That’s difficult because it requires us to think way beyond our current level of technology. We somehow have to keep our feet on the ground while staring into the sky.
In the book you discuss how advances in technology have changed our thinking—or should change our thinking—in regards to SETI. Can you elaborate?
First was the laser, most significantly. I think people [now] feel that ET would probably use laser signaling rather than radio signaling. More recently people have suggested more exotic types of signaling—neutrinos being one possibility. I still feel that radio is probably best. But we might find evidence of alien activity that’s not a message, but a footprint they’ve left.
There is another scenario, one which has nothing to do with electromagnetic or neutrino signaling, which is that ET might use biological organisms as a means of sending information. Genomes are packed full of information. If you could get a message into a cell somehow it would just replicate and replicate. If you could do that in a way that doesn’t compromise the biological functionality of the host then you’ve got something that could endure for millions and millions of years. So rather than sending radio messages, I would be in favor of, for example, dispatching viruses—retroviruses—that would insert DNA into any DNA-based organisms. It costs nothing to search the genome, because people are sequencing genomes anyway. So why don’t we search as many genomes as we can get our hands on, not just human—just to see. It’s a crazy idea, but then all of SETI is slightly crazy. I believe we should do what we can do easily and cheaply even if the chances of success are exceedingly small.
What about the idea that aliens might be post-biological in nature?
I believe that biological intelligence is a very transitory phase in the evolution of intelligence. If we, for example, get through the next few decades—the bottleneck we’re facing now in terms of energy and environment—we will see more and more a transition to transhumans and to human machine systems and ultimately to all-machine-type systems. The smartest entities on the planet will not be flesh and blood. I’m sure that would be true of an advanced civilization anywhere else.
We should get away from this Hollywood image [of alien life]. I went to see Avatar, which is spectacular for its 3D wonderworks but pathetic for its storyline. It commits all the usual sort of fallacies.
Explain the implications of the speed of light on SETI, which seems an oft-overlooked factor.
Yes, it has been brushed aside, and many science fiction fans overlook the speed of light. But if you believe the theory of relativity—which almost all scientists do—then this is the fastest speed in the universe. Any type of physical interaction is limited to the speed of light. And though it’s fast by everyday standards, it’s slow by astronomical standards. It takes light about eight-and-a-half minutes to reach us from the sun; it takes over four years to reach us from the nearest star; it would take a hundred thousand years to reach us from the other side of the galaxy. The relevance here is that even in principle, our existence cannot be known beyond a certain distance. For example, a hundred light years away, an observer would see earth as it was a hundred years ago. So the existence of a technological community on Earth—at the very least having radio capability—could not, even in principle, be known beyond a few dozen light years from Earth. If there was an advanced civilization within that distance, it’s not inconceivable that they have picked up our first radio messages and beamed something our way. But even SETI optimists don’t think there’s likely to be a civilization that close. I like to take a thousand light years as a good sort of guesstimate.
When you put this to people who do SETI they reel around a bit, and say we could be dealing with a civilization that is so altruistic that it is prepared to beam messages to Earth based on a mere expectation that there might be [intelligent life here] in a few centuries or few millennia. It would make much more sense for them to wait for our first signals. They might as well just monitor us passively and then start beaming messages. I think the best we can hope for is to pick up a beacon that is broadcast to no one in particular—or stumble across somebody else’s messages going back and forth, much like eavesdropping on a telephone line. You have to be jolly lucky to be in the way, of course.
Is SETI science or pseudoscience?
When it began I think a lot of people felt it was pseudoscience; one might as well have expressed a belief in fairies, to be perfectly honest. But over the years it has become more respectable, and the SETI Institute now has a lot of joint projects with NASA, and many of these are astrobiology [as opposed to SETI]. So I think it qualifies for being a science, but ultimately we must have the usual standards of verification, and it’s obviously very speculative. It’s speculative even by the standards of modern physics, which has a lot of weird and wacky stuff swirling around.
So I would like to distinguish between the practice of SETI and the conceptual basis of SETI. The practice of SETI is thoroughly scientific. When you talk to the astronomers concerned, these are professional scientists, and their day-to-day work is of the highest standard. There isn’t any doubt that they are going about their work in a scientific way. But the agenda itself is marginal. It’s very much on the fringes of what can be considered scientifically respectable.
What makes it acceptable to look for aliens, but not ghosts?
This is very subtle but it has to do with the conceptual framework in which you fit it. Physics provides the best example. When physicists go looking for the Higgs boson—as they are at the moment at the Large Hadron Collider—there’s a good body of theoretical work that has gone into that expectation, with precise predictions, even though it may not be there. The same is true for the neutrino, the famous ghostly particle that was postulated in the 1930s but wasn’t definitively identified until the mid 1950s. Why did people spend time looking for this ghostly entity? It’s because it had a well-defined place in physical theory.
So when it comes to looking for aliens we have to convince ourselves that it’s a rational thing to look for. Some people might take the view that it’s a crazy and pointless exercise, but at least in the case of extraterrestrial life we know the sort of thing it is and can understand how it would evolve. When it comes to ghosts, to take your example, there is no credible theory. We can make no realistic predictions of where to look or how to look. We can’t fit it in to a large body of scientific knowledge. That doesn’t mean there are no ghosts. When it comes down to this shot in the dark, if you look for something that connects to an enormous body of well-defined, believable theory and experiments, it’s very different from plucking something that doesn’t belong to science and saying, “We’ll look for that too.”
It’s clear you feel that SETI—including traditional SETI—is still worth pursuing, even though the odds of success are long.
While the chances of success are very small, the consequences would be enormous. If they [SETI scientists] succeed, it will probably be the most momentous scientific discovery in history. So to allocate some small fraction of the world’s resources to addressing such a very deep question is certainly justified. And even if SETI fails, it’s very healthy that we address issues like: What is nature? What is humanity? What is our destiny? What do we mean by life? What do we mean by intelligence? What is our place in the universe? These are all good things to think about, even if we never pick up a signal.
Part 2 of this interview