The London Times
Source: The Times [of London]
Monday, August 31 1998
Features: Mind And Matter
Scientists have a new way of contacting extraterrestrials, says Nicholas Booth
The light way to track an alien
If ET is trying to contact us, he won't be phoning - he will use the powerful
flashlights that are lasers to draw our attention. Like lighthouses on the
unexplored seas of space, these unique flashes of laser light, which astronomers can
detect with simple equipment, will soon tell us whether any stars are harbouring advanced
That is the startling claim of the American inventor of the laser, Charles
Townes, who has long urged his colleagues to look for such tell-tale signs of alien
intelligence. All scientific searches to date have involved listening for radio signals
from alien civilizations; now a team from the University of California at Berkeley will
use a simple, antiquated telescope to try to spot the laser flashes.
At 83, Professor Townes, a Nobel prizewinner, is delighted to be vindicated. "I
proposed this idea in the Sixties," he says. "Now a group of astronomers will
start to make a search this autumn. I am very pleased."
This attempt is the start of a new era of astronomy. The method is, according to the
astronomer in charge, "embarrassingly simple". Embarrassing because it could
have been undertaken at any time in the past four decades, but Professor Townes's notion
of looking, rather than listening, was largely ignored.
"If there are aliens sending us messages by laser, we will see them," says Dan
Werthimer, the director of Berkeley's Search for Extraterrestrial Intelligence (SETI)
Unlike the aliens in movies, who frequently speak English, the real ones would probably
not use Morse code. "They would send very short, powerful pulses of laser light that
would be unmistakable. It doesn't require that much energy to do," Dr. Werthimer
Later this autumn, he and his colleagues will use a 30in telescope - modest by
professional standards - at Mount Leuschner, about 20 miles east of Berkeley, to look for
laser flashes. Light captured by the telescope will be split into two and fall on to
photo-multiplier tubes, which will amplify the signal. If both see unusual flashes at
specific wavelengths -lasting perhaps a few billionths of a second, with a power output
greater than that of the stars they are looking at - they will have hit the jackpot.
Seeing signals in the two separate halves of the beam means that they could not be
artifacts of the detection process.
Lasers are the only way that bursts of light could be sufficiently concentrated. As with
the powerful search beams of a lighthouse, they could be directed to specific stars such
as our Sun. Lasers work by exciting gas atoms and forcing them to give up their energy in
the form of an intense flash of light.
"We could easily send a message into space to other civilizations," Professor
Townes says. His Berkeley colleagues agree. According to Dr. Werthimer, you could attach a
simple laser to an optical telescope and direct it to nearby stars and send messages.
"You could do that with a laser that transmits one megawatt," Dr. Werthimer
says. "That's about the same power as a television station."
But that is far into the future. For the moment, the Berkeley team is starting its own
modest search; improbably, this optical work will cost just $20,000 (#11,400) a year, a
sign of the times for SETI research. Searching for aliens has been criticized by some as a
kind of wishful thinking, a subject without a science. And American legislators certainly
agree: NASA's ambitious program of SETI research using radio telescopes was canceled in
However, with private funding from supporters such as the science fiction author Arthur C.
Clarke and the film director Steven Spielberg, SETI struggles on.
Others have said that finding evidence for alien civilization will be impossible. A
similar thing was said to Professor Townes during the late 1940s after he proposed the
forerunner of the laser, the maser (which produces microwave radiation rather than light).
As a researcher at Bell Labs in New Jersey, he was a world expert on microwave
spectroscopy, the probing of gases using radio waves. He realized that by using molecules
to amplify signals, he could generate a powerful source of radiation. After he discussed
the method in a scientific journal 50 years ago, "more than one Nobel laureate said
it would never work. It was viewed as a crazy, cute idea and there wasn't much to
Early one spring morning in 1951, while sitting on a park bench in Washington, Professor
Townes had what he calls "divine inspiration" of how to make a maser work and
its possible applications. "I recognized that it could be a sensitive amplifier or
atomic clock," he says.
Throughout the 1950s, the wavelengths used to probe gases were made progressively shorter
- so much so that he could get down to optical wavelengths. Together with his
brother-in-law, Arthur Schawlow, he developed the laser. Accordingly, Townes won the Nobel
Prize in 1964 (along with two Russians who had independently come across the same
principle). Lasers can now be found everywhere, from supermarkets to home CD players to
"It comes home to me when I hear of friends who have had their sight restored,"
Professor Townes says. "To me, it was clear that the most important uses would come
from connecting up optics and electronics."
Proof positive comes from the telescope now being used by Dr. Werthimer's team (it is
normally used to train Berkeley undergraduates). In 1959 - the same year in which a
workable maser was developed - two radio astronomers declared that detecting radio signals
would be the only way to find aliens. As a result, the scientific community tended to
dismiss any other wavelengths that could be used to send messages.
By the mid-1960s, Professor Townes had moved to Berkeley and was working at the Space
Science lab. By then, his idea was bolstered by the discovery of naturally existing masers
in space. There are vast clouds of gas between the stars which can act as masers. Their
constituent molecules are naturally excited to such an extent that they amplify microwaves
across the vast firmament of the heavens.
Any sufficiently advanced alien civilization would be well aware of that and could emulate
the process. Professor Townes points out that these clouds have been emitting intense
radiation in all directions, but it was only recently that humanity has acknowledged their
"If we'd have found them earlier, then we could have developed the laser
sooner," Professor Townes says. "We didn't look. Other civilizations might have
taken their cue from natural masers in
This autumn, the Berkeley group will systematically look at 2,500 nearby stars. The
criterion is fairly simple: they will be Sun-like stars, around which planets like ours -
and corresponding civilizations - could have evolved.
All involved agree that the search is a long shot, with truly astronomical odds against
But the final word goes to Professor Townes, who insists that, as with the invention of
the laser, the discovery of life in space is simply a matter of looking hard enough.
"We don't know what we will find, so we must keep looking."
Copyright ©, 1998, The London Times