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
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
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
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
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
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
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
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
Anthony Crolla: How did you get into this field of
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
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."
Michael Vigor: What are the future plans of the SETI
Seth Shostak: "The SETI Institute, where I work, is
building a new radio telescope called the Allen
Telescope Array, and this telescope will be 100 times
faster than what we're doing today. We're also
starting experiments to look for flashing laser pulses
from other worlds."
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
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
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
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
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
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
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
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
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
Affro Em: Would mobile phone signals be heard by
Seth Shostak: "No. They're entirely too weak - in
fact, we often don't hear them properly here on
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
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
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
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
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
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."
BBC Host: That is all we have time for. Here is Bob
with a final word....
Seth Shostak: "I appreciate everyone's interest, and
the very good questions, and I hope you'll stay tuned,
because we will!"