Geoff Marcy has spent the better part of his career peering into the depths of space in the search for exoplanets and brown dwarfs. His pioneering work has resulted in the discovery of over 110 planets outside of our own solar system - including the first system of planets orbiting a distant star. But now, Marcy has decided to shift his focus and direct his efforts at detecting something just a bit more elusive: extraterrestrial intelligence.
Marcy was recently appointed the new Watson and Marilyn Alberts Chair for SETI at the University of California at Berkeley where he hopes to leverage his expertise as an astronomer. We spoke with Marcy about his work as a planet hunter and his new role with SETI.
Looking back at the tremendous progress being made by planet hunters these days, what can you say about the field right now and where it's headed?
The most compelling question is how common Earth-like planets are. We still don't know if planets that have both liquid water and dry continents are common or rare in the Milky Way Galaxy. It remains possible that most Earth-size planets are either water-worlds or desert worlds. Technological life is most possible on a planet that has both water and land. Perhaps such planets are rare, no more than one in ten thousand planets in the habitable zone.
What is it about SETI that attracted you to the endeavour and the position?
I would love to know if other intelligent beings exist elsewhere, and if so, is our nearest neighbor a few light years away or thousands of light years away. The typical distance between intelligent civilizations will determine if interstellar travel is cost-effective or too expensive, time-consuming, and daunting. Everyone would love to know if our Galaxy is teeming with life, as science fiction suggests, or instead is mostly empty with a few lonely civilizations scattered far and wide from each other.
How will your previous work as an astronomer inform the various strategies that SETI can employ in their search for intelligent life?
The search for signals from intelligent species will involve analyzing the light from other civilizations. I am fortunate to have some experience with analyzing the spectrum and the intensity of light from astronomical objects. That experience will help me design new observational techniques that might reveal the faint signal from another civilization. For example, if alien life relies on lasers to communicate, I hope to use my knowledge of spectroscopy to detect the light at one wavelength that comes from lasers. I will also use the world's best telescopes and their detectors to detect signals from advanced life. My past experience may help me use that equipment.
As the new SETI chair, what are some of your short-term and medium-term goals? What is SETI's biggest challenge right now?
Sadly, I have a short term goal which is to simply finish all of the exciting exoplanet projects I'm working on. The NASA Kepler mission is so exciting, and I want to continue working with the Kepler team. But I must finish some analyses of those data, before I can turn my attention to SETI. That will take 6 months. But then, I want to look for laser lines and Dyson Spheres.
Traditional SETI involves the search for radio transmissions, but some experts believe that incidental electromagnetic radiation of this sort could never reach Earth. What are you thoughts on this, and what are some other ways that SETI can look for intelligent life?
It is still very important to search for radio transmissions. The search for signals at different radio frequencies, with more powerful radio telescopes, is still extremely important and viable. The signals from the aliens might be hitting Earth right now! We just need to tune our receivers to those frequencies and build big telescopes to detect them. However, SETI must also search for signals in infrared and optical light that the advanced civilizations may be broadcasting at. We must look for laser transmissions, just as modern satellite communication uses.
It's been over 50 years since the advent of SETI and we have yet to detect any signs of extraterrestrial life. What is your take on the so-called Great Silence?
I believe we must take the Great Silence seriously. It suggests that advanced life is rare in the Milky Galaxy. If it were teeming with life, we would have already picked up some signals from them, and indeed they would have sent robotic probes to Earth to examine us. The lack of signals from ET suggests that advanced, technological life is rare. Perhaps our Galaxy has only a few such civilizations, separated by thousands of light years, too far apart to communicate. If so, we humans are existentially isolated from our Galactic friends.
Still, we must search for the text messages of our extraterrestrial friends, so that we can text back.
It's thought by some futurists that advanced extraterrestrials will have migrated from the biological to the postbiological realm, living a kind of digital existence. Has SETI considered the challenges of searching for machine-based civilizations?
We humans will, during the upcoming century, replace our bodies with mechanical, and perhaps computational, parts. I doubt we will replace our brains any time soon. I would love to hear some ideas about how we might search more efficiently for such robotic species. My guess is that they will be limited to transmissions among their Galactic colonies by the same electromagnetic waves that we organic folks are restricted to. But the robots may be able to travel among the stars, taking centuries, as they would have no deteriorating DNA telemeres to cause aging. We should be trying to detect the robot-to-robot transmissions at optical, IR, UV, or radio wavelengths from the multitude of such replicating machines.
Listening for signals from space is one thing, but transmitting messages in hopes of attracting the attention of extraterrestrials is quite another. Does SETI have any plans to engage in what is called Active SETI or METI - sending messages to extraterrestrial intelligences?
No one wants to flash a Galactic marquee: "Come to Earth! All You Can Eat: Tasty Organic Meat!" But we are announcing our existence in many ways unwittingly. The "I Love Lucy" episodes are 50 light years from Earth, and there is no getting Lucy back. Our military lasers are shooting from ground-to-satellite, beaming their secret messages to the stars. Even we astronomers are using "Laser-Guide-Star Adaptive Optics", pointing the lasers directly and specifically at all sorts of astronomical objects where the aliens may reside. The Earthling marquee is bright and flashing.
SETI's Jill Tarter of the SETI Institute in Mountain View recently spoke out and criticized the abundance of negative portrayals of extraterrestrials in science fiction films these days. Do you agree with Jill that ET will almost certainly be friendly?
Jill is right. We are painting an unfair picture of the aliens. If they overcame their competitive Darwinian roots, they are much, much more empathic and diplomatic than we humans have proven to be when we encounter other "civilizations".
Some skeptics argue that SETI is unscientific and predicated on nothing more than wishful thinking. What do you say to those critics?
SETI is not unscientific. When we detect a signal, the most important next step is verification and confirmation by other scientists who have no stake in the answer. Such validation of a signal is the hallmark of science. Any SETI signal must be reproducibly detected by anyone.
However, I am disturbed by those SETI practitioners who are "wishful". Scientists should suppress any "wish" they have for a particular answer. Instead we should keep any open mind, answering the dry, cold, and frightening question, "Are we alone?". An answer either way, yes or no, will be shocking for we Homo sapiens.
Image via NASA / Media Telecon.