Photo: Dr. Seth Shostak, SETI Senior Astronomer.

Ben: Do you believe in extra-terrestrials?
Seth Shostak: "Well, Ben, if I didn't, I wouldn't continue to do this work. It would be very frustrating to think that we're looking for something that doesn't exist."

Duncan: How do you use radios to listen for aliens?
Seth Shostak: "The scheme that we use is to point very large antennas in the directions of sun-like stars, and look for signals that are clearly produced by a transmitter, and not natural cosmic static."

Sara: What type of signals do you expect aliens to make?
Seth Shostak: "Well, Sara, I expect aliens to make all kinds of signals, but the kind that we look for are so-called narrow-band signals. These are at one particular spot on the radio dial. These are the types of signals that would be most easy to detect from great distances."

Vicki: Is there any possible chance we could encounter alien life in our lifetime?
Seth Shostak: "I don't think we're going to encounter it face-to-proboscis. I don't expect them to come here, and we're not going there, but we might find a signal from them in the next several decades."

Martin: Does the SETI dish transmit as well as receive?
Seth Shostak: "The Arecibo antenna does have a powerful transmitter, but we don't use it. We're just trying to eavesdrop."

Mike: Do you think any contact will be understandable to us, will we recognise it?
Seth Shostak: "If they are being altruistic, and trying to educate us, they may make their message simple for us. But personally, I don't expect this. I suspect we'll not understand their message."

Rob Sharp: If we're not alone, why all the sightings and no contact?
Seth Shostak: "Most of the sightings can be explained as natural phenomena or aircraft or balloons or other mundane stuff. I still haven't seen any evidence that any of these sightings involve alien spacecraft. I think the aliens exist - I just don't think they're visiting."

Marcos Scriven: There is a screen saver which uses your PC while you're not using it, to analyse SETI signals. Do you know if anyone has turned up anything interesting using this method?
Seth Shostak: "There has been a lot of processed data, but it will be a few years before they will know if SETI@home has turned up ET's faint whine."

Simon Zerafa: What are the chances that ET might be a machine intelligence rather that biological?
Seth Shostak: "Personally, I think it's quite likely that the bulk of the intelligence in the galaxy is not soft and squishy, but rather, artificial."

Michael Somers: Do you think places like Stonehenge where created by aliens?
Seth Shostak: "That would be a disservice to druid engineers! I'm sure Stonehenge, the pyramids, and the lines in Peru, were all made by clever humans."

Loz Herbert: If aliens were found, would it not be kept quiet due to the potential mass hysteria?
Seth Shostak: "No I don't. The majority of folk believe that the aliens are already here, and I don't see them rioting in the street about that. Any discovery would be made public immediately."

Neil Mackie: Has it been confirmed yet that life did exist on Mars?
Seth Shostak: "Alas, Neil, not yet. There is some very suggestive evidence, but a lot of controversy. We may not know for sure for many years."

Steve: Is there any means for sending messages so that they reach other planets more quickly than they do with radio waves?
Seth Shostak: "As far as we know, nothing can beat radio or light for speed - Albert Einstein told us that, and so far there's no reason to disbelieve him."

Kevin Mckay: Would aliens have to be water or carbon based?
Seth Shostak: "Not necessarily, but carbon is exceptional in its ability to hook up with other atoms and make complex molecules, and life, as you are undoubtedly aware, is mostly about complex molecules."

Tania Jones: What would aliens look like?
Seth Shostak: "I haven't the slightest idea!"

Tony Stone: If the aliens are at a state to receive would they not have been broadcasting themselves?
Seth Shostak: "The problem is, we've only been broadcasting for half a century. So our signals haven't reached many star systems yet."

Will: Do you think aliens are listening for us?
Seth Shostak: "That doesn't sound unreasonable to me, to use a cautionary double negative!"

Vill: Seth, do you think that there is life as we know it?
Seth Shostak: "Yes, in the sense that I think that a lot of extra-terrestrial life will be based on carbon chemistry the way ours is, so in that sense, we know it."

Anthony Crolla: How did you get into this field of astronomy?
Seth Shostak: "I was a radio astronomer, and the techniques I was using to study galaxies are exactly those required to listen for ET."

Unlixes Neilstropp: Why is it so many scientists believe alien life would be carbon based?
Seth Shostak: "Again, carbon is good at making complex chemistry. There is also a lot of carbon around, and in any liquid environment, you can expect it to start doing interesting things."

James Carter: If you were listening to our radio/TV channels, and watching for instance the events of World War 2, would you contact Earth?
Seth Shostak: "I don't think that the aliens will be put off by our petty problems any more than Columbus refused to discover America because the American Indians were occasionally at war with one another."

Bob Davies: Do we have a plan in the case of a 'Contact' scenario?
Seth Shostak: "We do, but it's very simple. It merely states that we should tell all the astronomers, tell the public, and tell the government."

Jill Newcombe: Can you give me some info on clubs and organisations I can join?
Seth Shostak: "There are two possibilities that come to mind. One is the SETI Institute's Team SETI, and the other is the free screensaver - SETI@home. Check the SETI Institute's website: http://www.seti.org for more information."

Jason Timmins: What about the 1976(?) signal?
Seth Shostak: "I think Jason is referring to the so-called 'Wow' signal, (which by the way was 1977), however, every attempt to find that signal again has failed, so we can't assume it was ET."

Phil Elias: How can you be sure that aliens know about radio waves and are able to detect them?
Seth Shostak: "The aliens will have the same physics we do, and they'll surely discover this very efficient way of sending information from one star to another."

Alex Locke: About radio waves - how could aliens hear our radio signals amidst all the noise from the Sun?
Seth Shostak: "Surprisingly, Alex, the Sun actually makes weaker radio signals than the BBC. So they could indeed sort out our transmitters from the Sun's background noise."

Paul Pitchford: Seth, I am very sceptical and struggle to believe that there is intelligent life forms out there. What makes you think there is?
Seth Shostak: "If we are alone then that's extraordinarily remarkable in such a vast universe.Personally, I don't think we're that special."

A Muppet: Have we found *any* planets within the correct distances from their suns to support life?
Seth Shostak: "There are a few, but they are giant planets, not the kind of world ET would like to call 'home'. But we expect that there are also many small planets that we cannot yet find. The limitations of the techniques that we use can only find very large planets."

Stuart Travers: In a "Star Trek" world, all the alien races walk on two legs or something similar, what do you think the chances of real ET's being like us are?
Seth Shostak: "Well, when I go to the local zoo, I find that most of the critters walk on four legs, and most of the critters in my house walk on six legs. So, it's not clear to me that ET will only have two."

Chris Carter: Are you ever worried that programs such as SETI might attract the attention of malevolent aliens?
Seth Shostak: "Well, keep in mind that we don't broadcast - we only listen. So the aliens won't know that we're even doing SETI.I think the likelihood of malevolent aliens existing is as likely as me going into the backyard, rooting out the ants and exterminating them! I don't think we're that interesting."

Marianne Oates: If you discovered life, Seth, what would be the first thing you would do?
Seth Shostak: "Probably lose a lot of sleep! But for the next week we would be busy verifying the signal and collecting as much data as we could."

Anne Marigold: On the basis of 'nothing unites like a common enemy' do you think proof of ETI would unite the people of the world?
Seth Shostak: "It's a nice thought, but I'm somewhat sceptical! I think there would be a lot of contention about who should have access to the big radio telescopes in order to get this new information."

Steve Norton: If a radio signal took fifty years to find a hit, how long would it take us to travel to the destination?
Seth Shostak: "Radio signals travel at the speed of light, which is at least ten thousand times faster than our best rockets.In the future, we might be able to build rockets that could go at ten percent of the speed of light, so it would take five hundred years to get there."

ab3456: Will SETI ever stop?
Seth Shostak: "I certainly hope not. Remember, we're looking for a needle in a haystack, and we've checked out a handful of hay, so it's very early days to think about stopping."

Affro Em: Would mobile phone signals be heard by aliens?
Seth Shostak: "No. They're entirely too weak - in fact, we often don't hear them properly here on Earth!"

Nastar: How far has the original Voyager probe reached and are we still in contact with it?
Seth Shostak: "It's now ten thousand million kilometres from earth, and we still receive signals from these craft."

Paul Smith1: Do you view "first contact" as an essential part of this planet's future survival?
Seth Shostak: "I'm not so sure it's essential for our survival, but I do think it will happen."

Farris Willson: Even if we had a contact how can we confirm it was from ET and not a Pulsar or other different waves?
Seth Shostak: "The characteristics of the signal would betray it as being sent by a transmitter and not by some noisy natural source. For example, pulsars spread their radio energy all over the dial, which is very inefficient. ET wouldn't do that."

Colin Finch: If contact is established, who agrees what we send back?
Seth Shostak: "Good question, Colin. At the moment, there is a proposal to require international agreement on any reply, but frankly, we've been sending television signals into space for 50 years. So our reply is already out there."

Simon Stephens: Seth, do you believe that the American government has covered up alien aircraft discoveries?
Seth Shostak: "No, I don't. No matter what you may think of the American government, they're not that efficient!"

Ayasami Fukuno: Do you think Aliens have any special powers like teleporting and stuff?
Seth Shostak: "Well, I'm sure they're more advanced than we are - the ones we will hear. But they're stuck with the same physics that we are. Teleporting might not be allowed by physics - even for aliens!"

Matt: What do you think the chances are of a real 'Planet of the Apes'?
Seth Shostak: "All I know is that our ancestors managed to wipe out the Neanderthals and the apes are a lot further behind us, in an evolutionary sense, than the Neanderthals were. So I personally am not worried. But I am stocking up on bananas!"

Tricia: Why expend even more dollars on detecting intelligent life in space when the fact of its existence can be of no material benefit to us?  Is it that scientists such as yourself are really philosophers at heart?
Seth Shostak: "I'll take that as a compliment! I think it's mostly curiosity, in the same sense that Galileo did his work on the basis of curiosity. We always want to know what's over the next hill."

James2: Can you give a quick synopsis of what you have discovered so far?
Seth Shostak: "Yes, we can - we have yet to find ET's signal, period! But that may change tomorrow. In terms of the area that we have covered, essentially, all of the sky has been looked at with low sensitivity, but only 500 star systems have been carefully scrutinised."

Vicky Webb: Seth, if a normal person would be scanning through the radio channels could we hear signals from ETs?
Seth Shostak: "Unfortunately, Vicky, unless they've bought the local AM radio station, they won't. You need a much larger antenna than you're likely to have at home."

Paul Calderbank: If it takes 15 billion years to make a sentient life form able to view the universe (i.e. us), how do you expect any one else to be ahead of the game?
Seth Shostak: "Keep in mind that the earth has only been here for four and a half billion years, so there are plenty of older star systems, and consequently, I suspect, plenty of more advanced societies."

Seth Shostak: "I appreciate everyone's interest, and the very good questions, and I hope you'll stay tuned, because we will!"