Few endeavors have the potential to achieve a discovery so profound as the existence of intelligent life beyond our own planet. It's certainly an innate human desire to not want to be alone and to search for other beings that might share our thoughts, struggles, ideas, and curiosities. We can imagine that humans have sought out others to communicate with since primitive tribes wandered the continents. Currently, such a search is meticulously being conducted on a grand scale by the SETI Institute. Founded in 1984, the institute operates as a private, nonprofit organization, and uses methodology with a solid technological foundation. Using teams of their own scientists and astronomers - and collaborating with NASA, other government laboratories, and technology companies - they collect electromagnetic energy emitted from beyond earth and analyze it for characteristics that would suggest another "technological civilization".

The project has its critics. To start with there are two major physical laws that work against its success:

Signal attenuation: Even a very strong signal will disperse over a great distance and can become too weak to be detectable by a receiver here.

Speed of electromagnetic transmission: This speed limit is insignificant for most purposes on Earth, but becomes a significant factor when dealing with the vast size of the universe. A signal transmitted from two hundred light-years away would take two hundred years to reach us. Therefore any message we receive from that location would need to have been transmitted two hundred years ago. Even if a life-form there has the technological development to transmit a viable signal now they may not have been at the necessary stage of development that long ago.

In addition to these things, you also have to discount for the probability of life-supporting environments elsewhere in the universe. The limitations of our current instruments and knowledge make this an unknown factor, however. For these reasons, as well as some others, many people feel that "listening" for an intelligent signal is a waste of time.

There are also very valid reasons for optimism, though. Robotic exploration just within our solar system has already revealed the existence of amino acids and other organic compounds beyond Earth. These are important building blocks which make up our own biology. Also, newly implemented instruments are revealing the existence of many other 'exoplanets' elsewhere in the galaxy, and probably throughout the universe, and as these instruments are becoming more sensitive they're detecting more of these planets. On a philosophical level it's hard to imagine that a universe as vast as what we know would exist only to host life on a single planet in a single solar system in a single galaxy.

For these later reasons there are many people who are enthusiastic about the possibility of discovering intelligent life at some point, and feel that this pursuit is important. One of them is Dr. Seth Shostak, senior astronomer with the SETI Institute. He's also a friendly and hard-working spokesperson for the institute, and was happy to answer some random questions when we contacted him:

Us: When did you become interested in the search for extraterrestrial life and how did you get started with the SETI Institute?

Seth: Well, I think I got interested at the age of eight because I got interested in astronomy. Then, by junior high school I was reading books about the possibility that we might be being visited ourselves so it’s a very long-standing interest of mine, but my interest in actually doing SETI work didn’t develop until I did an experiment in Europe using a radio telescope there in 1981, together with Jill Tarter, so I had done quite a bit of reading about it but had never done it myself. However, I was a radio astronomer so I knew how to do the experiments with the radio telescopes that we were using in Holland and I did that experiment with Jill Tarter - she was on a sabbatical at the time. We published that in 1982 and then I moved to California for completely different reasons in 1988, and two years later they called me up and said; "are you interested in a job here". So that’s how it happened.

Us: What about that work has given you the most satisfaction?

Seth: Well I think because it’s a big picture kind of a question. A lot of people have jobs where they worry about next year's taxes or this quarter's bottom line or whatever, and all that is great, but it’s kind of nice to be able to work on a question that’s been asked for a very long time and that would be very, very interesting to answer, so it’s a big picture question. It’s sort of like the difference between being a shoe cobbler in Barcelona or sailing across the Atlantic trying to reach the Indies, the way Chris Columbus did.

Us: Do you subscribe to The Drake equation as far as how it suggests a probability of extraterrestrial life?

Seth: Do I subscribe to The Drake Equation? I get it every month. It’s delivered to my front door and I figure the subscription price is low. :-) Actually, I think The Drake Equation is a great way to consider the source of things that we need to know. It was originally intended as an agenda for a meeting and I think it’s actually still very, very useful. There are still some things that are not encompassed by The Drake Equation; for example if you have colonization or if you had life able to spread from one solar system to another then The Drake Equation is missing perhaps some important terms there, and tends to under estimate the number of civilizations that you could find, but on the other hand I have to say in general I find it still very, very useful. It’s a great way to decide what you don’t know.

Us: What portions of the electromagnetic spectrum do you monitor?

Seth: Well, traditionally we have typically monitored frequencies near the hydrogen line, the 21-centimeter line, but our big observing project, Project Phoenix, looked at frequencies from about 1,500 megahertz to 3,000 megahertz. No that’s not right, it’s more like 1,200 megahertz to 3,000 megahertz, because the 21-centimeter line is at 1,420, and we were way below that. So it was almost three, well two gigahertz of the radio spectrum and that’s what we did a few years ago where the Allen Telescope Array will actually be able to choose from actually less than one gigahertz up to eleven gigahertz so that’s an enormously wider range.

Us: Ok, that was going to be my next question, what signal sources do you use to gather that information?

Seth: The instruments we use, I don’t know if they are signal sources, they better not be signal sources actually. :-) We have used in the past very large radio telescopes, from the Parkes telescope in Australia to the Arecibo telescope in Puerto Rico to telescopes in West Virginia, but in the future we will be using, for our radio searches, the Allen Telescope Array which is in Northern California in The Cascades and it’s an instrument that’s actually designed to be very efficient at doing radio SETI work, so I look forward to that.

Us: So that’s going to be your principal instrument and that’s going to give you more capability than you've had in the past?

Seth: Much more capability.

Us: The SETI@home program that people run on their computers, what does that actually do with the data that gets downloaded to their computer? How does that help your program?

Seth: It doesn’t help ours at all because of course it’s not our project, that’s a project of The University of California in Berkeley, not the SETI Institute. The data from their '@home' processing are sent back to the Berkeley SETI group and they use that to decide which candidates they're going to look at more intently. It’s a very, very good program, essentially the biggest computer in the world.

Us: But it’s an independent project from your institute?

Seth: Yes, it’s a completely different project.

Us: So far you have not found anything that would indicate intelligent life and some people have the opinion that nothing has been accomplished therefore. But there’s definitely been spin-off benefits in the meantime, kind of like when NASA flew to the moon and people said all we did is bring some rocks back, but they ignore the technological advances that were brought about by that. What would you say has been some of the spin off benefits of your project?

Seth: The spin off benefits actually from SETI I think are mostly in the development of radio frequency technologies. In other words, radio technology, new kinds of amplifiers, new kinds of digital receivers, algorithms for searching for signals. All of that might have practical benefit actually in all sorts of areas ranging from telecommunications to defense. I’m sure all of that will be used in those areas for sure, but that’s not why we do it. We don’t do it for the spin-off. It’s like saying, "Well Chris, you’ve found this new continent but what’s the spin off? You’ve traveled half way around the Atlantic. Well you really haven’t done anything so far, so is this really worthwhile?" And you might have said, half-way across the Atlantic, that this wasn’t really worth while, but that might have been a very myopic point of view.

Us: You have some large companies, such as Sun Micro Systems and Hewlett-Packard, that are contributors to your program. What would be the symbiotic relationship there? What are they looking to get out of it, or are they just as interested as you are in finding life?

Seth: As far as giving us money, Hewlett and Packard themselves actually did. They found it personally interesting. Hewlett-Packard has given us some equipment, it is true, but that was in the days when Hewlett and Packard were giving us personal money. Sun Micro Systems, of course their chief technology officer has been a long time member of our board of directors, and they just find it an interesting thing to do. So they help us out with various contributions of hardware and things like that. But the big money donors have been Paul Allen, at least these days, and of course the thousands of other people who simply send us money because they find it an interesting thing to do. I don’t think they're looking to make a profit.

Us: You work closely with the NASA Ames Research Center. What’s the nature of that cooperation and in what way do you help each other?

Seth: NASA Ames is where NASA's SETI program was headquartered, and when I came to work at the SETI Institute, in fact, it was a NASA program and it was run out of Ames, so we have historical ties to Ames and we continue to work with them in all sorts of areas. Many of our astrobiology researchers have their offices at Ames. Remember the Institute has far more astrobiologists than SETI scientists and we also do educational projects for NASA, in fact my weekly science radio show is partly sponsored by NASA. We have lots of projects with NASA Ames, and in fact it’s not at all clear that SETI itself might not be part of NASA again. In fact it was killed in 1993, but only for one year, and there’s no reason in principle why it couldn’t be reinstated, at least part of it as a NASA project, so that might happen too. But in the meantime we have a lot of overlap with NASA Ames. Probably a good percentage of our astrobiology researchers are actually headquartered over at Ames. That’s where they have their offices even though they’re SETI Institute employees.

Us: If you do find some signal from intelligent life - a lot of people have used the example of the "I Love Lucy" TV show traveling out into the universe - and somebody picked that up, they would need to understand our raster-scanning system to know how to make an image of it that made sense. If you received some sort of signal do you have a system in place to try to decode it, or at this point are you just looking for a signal that you might think is from intelligent life?

Seth: In fact we do not look for actual signals now - we don’t look for the modulation - we integrate the signals, it’s like making time exposures, so that means all the modulation has gone away. So there’s no point in having software or decoders or anything else sitting around trying to figure out what the message means. That would be a subsequent step, but it would take a far larger instrument to pick up the rapid changes in any signal that would tell you these are the bits, this is the information and this is what you ought to decode. Our primary job is to find out they are on the air and after that I think you could find the money to build a much larger instrument that would be necessary to pick up the modulation, the message.

Us: If you did find a signal that you felt was from intelligent life, is it true that the speed of light would prohibit a two-way conversation if they were very far away?

Seth: Well, obviously if they are very far away then sure. If they were a thousand light years away then a conversation would be very tedious! :-) So I’m not counting on two-way conversations, then again I’m not counting on a two-way conversation with ancient Greeks either, but one-way conversations are still of interest.

Us: I’ve noticed that some of NASA's projects have discovered amino acid-like compounds. Do you find this exciting or do you think it increases the probability of finding what you’re looking for?

Seth: Where specifically?

Us: Recently there was a probe that gathered some ejection material from one of Saturn’s moons.

Seth: You may be talking about the moon Enceladus. You can make amino acids very easily it turns out. There have been amino acids found in the Murchison meteorite and I think it fell in the 1960’s. There’s organic material in almost everything we look at from space, and that doesn’t mean that life is very easy to get started but it does mean the building blocks of life are very commonplace and that of course is a very encouraging sign because it means that every solar system will probably have these molecular building blocks. But it’s a long way from an amino acid to a protein, of course, and that shouldn’t be underestimated.

Us: So the recent discovery I mentioned would be really nothing new then?

Seth: Well it would be interesting in terms if it was Enceladus, if that’s what you’re talking about, because that’s a big iceball, so that would be interesting to know if there was more to it than just water and ice - if there are actually some organics in there - because there could indeed be life down at the bottom of that blowhole on Enceladus. It’s a long shot but it is certainly possible.

Us: What developments does the SETI Institute have planned as part of its future mission?

Seth: We will continue to press the search with new technologies. Something that the public tends to overlook is the fact that modular technology allows this experiment to get faster all the time and in fact to follow Moore’s Law pretty much - double in speed every 18 months. Whatever SETI experiment we are doing five or ten years from now will be literally hundreds of times faster than what we are doing today and I think that’s the path we will follow, and look forward to success...

Learn more about SETI and the Allen Telescope Array