[tt] NS: Seth Shostak (interview): The alien hunter

Fri Sep 26 17:59:26 CEST 2008

Seth Shostak (interview): The alien hunter
http://www.newscientist.com/article.ns?id=mg19926741.900&print=true
17 September 2008
Barry DiGregorio

Watch a video about the Allen Telescope Array, the new telescope
being used to hunt aliens

Are we alone in the universe? Astronomer Seth Shostak has dedicated
his career to trying to find out, with the Search for
Extraterrestrial Intelligence project. Shostak talked to Barry
DiGregorio about why he's sure that intelligent aliens exist, the
powerful new telescope that will help in the hunt, and what he would
do if he detected a signal from ET

Why do you think intelligent extraterrestrials exist?

To believe that they don't exist requires positing that what's
happened on Earth is some sort of miracle. I find that premise a
tougher sell than to think that intelligence is a fairly frequent
development in a 14-billion-year-old cosmos.

When did you decide that the search for alien intelligence would be
your career goal?

I have a photo of the moment. In it I am reading a book that had
just come out by I. S. Shklovskii and Carl Sagan called Intelligent
Life In The Universe, while noting down some data on galaxies. That
was in 1967.

Was that a "eureka" moment?

Sort of. At that moment it occurred to me that the radio-telescope
antennas I was using to study galaxies could also be used to see if
we have cosmic company out there. It's hard to think of any project
of greater potential significance. And hey, there have been 10,000
generations of people before me who were interested in intelligent
life in the sky, but who couldn't do an experiment. How nice to be
alive when that's finally possible.

What does searching for alien intelligence involve?

We look for certain types of signals - ones that we can detect with
straightforward equipment here on Earth. That means radio and
visible light. For radio, most of the searches are trying to find
very narrow-band signal components, as these are the hallmarks of
deliberate transmissions. In the optical, we hunt for sudden bursts
of photons from alien lasers.

There are also a few searches for alien artefacts, like interstellar
rockets and Dyson spheres - hypothetical shells built around stars
by advanced civilisations to capture energy - but these efforts have
been limited.

How can you tell you're looking for the right thing?

The only way to be sure that we're using the right strategy is to
find something! But on the basis of the physics we know,
electromagnetic radiation - which is just another way of saying
radio and light - is the fastest and least energetically expensive
way to send information across interstellar distances. So it looks
good, at least on paper.

What do you say to Stephen Wolfram's assertion in New Scientist that
SETI is groping in the dark with no idea what to grope for?

It's easy to suggest that we're doing the wrong thing and, until we
find a signal, there is always the possibility that such a
suggestion has merit. I judge alternative SETI approaches on the
basis of whether they can be tested by experiment, either now or in
the foreseeable future. If a hypothesis is proposed without the
ability to use it to direct a search, then it's like telling
Christopher Columbus that he should swap his ships for jet aircraft.
Not helpful.

We have searched for alien life for 50 years and found nothing.
Isn't that long enough?

It might seem so, but in fact we've only examined fewer than 1000
nearby star systems - at least, over a wide frequency range and with
high sensitivity. That's an insignificant sample of galactic real
estate. Thanks to the march of technology, this fraction will
increase by three orders of magnitude over the next three decades.
At that point, maybe it would make sense to discuss whether we
should throw in the towel, assuming there's still no joy.

How will the new Allen Telescope Array help SETI?

We can use ATA constantly for searching, rather than relying on
someone else's antenna. It also allows scrutiny of more than one
star system at a time and it's designed to be able to keep up with
the feverish advance of digital electronics. When you add these
factors together, you get an instrument that's much faster at
sifting the galaxy for signals. So if there's a broadcast to be
heard, this new telescope may allow us to hear it far sooner than
previous approaches.

If we detect alien intelligence, is there any possibility of then
communicating with it?

There's a possibility, although conversation is going to be poky.
They'll probably be at least hundreds of light years distant, and
the chances that we'll understand anything of their message,
assuming there is one, are slight. That's just my prejudice, of
course. We'll have to wait and see if it's justified.

Couldn't it be dangerous to find, and possibly return,
extraterrestrial messages?

I think this is truly unlikely, given both the physical and cultural
distance that would separate us from them. If I were suddenly in
touch with termites in Nepal, my first thought would not be to go to
that far-off locale and destroy both them and their habitat.

What do you say to people who think that aliens have already reached
us, via UFOs and suchlike?

I say: "Don't tell me about the thousands of sightings every year.
Just tell me what you think is the very best case, the one that will
make it into the refereed journals of astrobiology." I'm still
awaiting a satisfying response to that request.

Why will the ATA focus on our galaxy's central region rather than
globular clusters that contain some of the most ancient stars in our
galaxy?

Globular clusters have their problems. They are very old stars, so
chances are that they don't have many planets - they formed so early
in the history of the universe that there weren't a lot of heavy
elements around to build rocky planets like Earth. And many globular
clusters are really far away, so any signals would be very weak.

The centre of the galaxy is the one unique spot in our galaxy. If
you are going to leave a transmitter beaming out a signal, putting
it at the centre of the galaxy means you can be confident that
everybody in the galaxy will look there sooner or later.

More than 300 planets have been found orbiting in other solar
systems in our galaxy. Wouldn't these exoplanets make good targets
for a SETI search?

We are looking at all the stars that have planets for one of the
first projects with the ATA. Most of the planets found so far are
not appealing as habitats for life. But even if you found 100
Earth-like planets that were thought to have life because oxygen was
detected in their atmospheres, it might not mean anything. Two
billion years ago the Earth had atmospheric oxygen but no
intelligent life to send a signal out. We have only developed the
ability to detect signals within the last 50 years. The point is
that you need lots of Earth-like worlds if you want to find a
signal.

What would you do if, today, you detected a signal which indicated
extraterrestrial intelligence?

Log in to my calendar and delete all meetings and obligations for
the next three months. And I'd probably stock up on Valium.

Astrobiology - Learn more in our out-of-this-world special report.

Profile

Seth Shostak has been interested in aliens since childhood. He holds
a PhD in radio astronomy from the California Institute of Technology
and worked for 10 years at the Kapteyn Astronomical Institute in
Groningen, the Netherlands. For the last 20 years, he has been a
radio astronomer at the Search for Extraterrestrial Intelligence
(SETI) Institute in Mountain View, California. His latest book,
Confessions of an Alien Hunter, is out next year.

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Weblinks

The SETI Institute website
http://www.seti.org/Page.aspx?pid=211
Seth Shostak's web page
http://www.seti.org/Page.aspx?pid=455
The SETI at home website
http://setiathome.berkeley.edu/
The Allen Telescope Array Wikipedia page
http://en.wikipedia.org/wiki/Allen_Telescope_Array