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Princeton
• Looking for alien light |
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Looking for alien light
Faculty, staff, students volunteers work to
refurbish old telescope for new project
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The old FitzRandolph observatory in the shadow of Princeton Stadium shows its years of neglect.
The locked, chalky steel door hides a water-damaged floor and a telescope that was abandoned more than 30 years ago as development in the Princeton area made the skies too bright for scientific observations.
But a dedicated group of Princeton scientists is working to change that. Every few weeks over the summer the volunteers, from full professors to undergraduates, have given up their Saturday mornings to scrape, paint and otherwise restore the observatory.
Ambitious but low-budget
It's not that the night skies around Princeton have suddenly gotten darker. The group's research plan doesn't require pure darkness. Their goal is to look for strong, short pulses of light that would be telltale signs of intelligent life on other planets. Such flashes would not be too hard to observe, even with the glow of streetlights.
This restoration-and-research project was organized by David Wilkinson, Cyrus Fogg Brackett Professor of Physics. He is working with Harvard physicist Paul Horowitz on part of an ambitious, but low-budget project called the Search for ExtraTerrestrial Intelligence, or SETI.
Most of the SETI project centers around looking for radio signals from extraterrestrial civilizations (as portrayed in the movie Contact) . Scientists have known for a long time, however, that a potentially more effective way to communicate large amounts of information over long distances is to use visible light. Fiber optic cables, for example, are capable of transmitting much more information than conventional electrical wires or radio signals. In the last couple of decades, our ability to perform such communication here on Earth has improved so dramatically that scientists have begun to wonder if optics might be the intergalactic communication system of choice. The search for optical alien signals has been dubbed OSETI.
Freshman seminar
OSETI at Princeton began with a freshman seminar. Wilkinson devotes most of his time measuring cosmic background radiation, the electromagnetic echo of the big bang. But last year he recruited Time magazine science writer Michael Lemonick to help him lead a freshman seminar titled "Searching for Life in the Galaxy." The instinctive appeal of this subject, he reasoned, was a perfect way to introduce nonscientists to basic principles of physics and astronomical observation and to indulge his own longstanding interest in SETI.
One guest speaker in the seminar was Seth Shostak, a staff scientist at the SETI Institute in Mountain View, CA. Shostak, a member of the Class of '65, was Wilkinson's first undergraduate advisee. Talking to the class by telephone link, he mentioned OSETI work being done by Horowitz at Harvard. In another session, Freeman Dyson of the Institute for Advanced Study addressed the class and also mentioned OSETI. These references prompted Wilkinson to call Horowitz, a long-time friend. He found that Horowitz needed a collaborator who could make independent observations, and Wilkinson knew just the place to do that: Fitz-Randolph Observatory.
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FitzRandolph Observatory was built in 1934, and for several years it housed the offices of the American Astronomical Society. In 1965 the University replaced the original refracting telescope with a 36-inch reflecting telescope that used a mirror provided by NASA as part of balloon experiments done by astrophysicist Martin Schwarzschild. That telescope was used for a few years to calibrate scientific instruments and to conduct scientific observations. By the early 1970s, however, the observatory was no longer used. Eventually, the shuttered dome leaked, ruining the floor, and the telescope itself began to rust.
Wilkinson did not have funding for a major renovation, so he began looking for volunteers. They turned out to be plentiful. "I sent out one e-mail and got all the response that I needed to get a crew," Wilkinson said.
Soon he had a working group of 17 people. Physicist Ed Groth joined in, as did chemistry professors Robert Cava and Robert Pascal, both amateur astronomers. Staff members Norman Jarosik, Kirk Alexander and Don Hortenbach also volunteered, as did several graduate and undergraduate students. Melissa Kemp and Brian Bower, both Class of '02, took summer internships in the Physics Department and worked on the renovation. Bower also put together an OSETI website that explains the project in layman's terms (www.physics.princeton.edu/~oseti).
The University has since pledged to fund half the renovation, while the physics and astrophysics departments will cover the rest. The price tag is estimated at $22,500. Already the group has removed the 36-inch mirror and sent it off to Chicago to have a new silvery surface put on. The telescope has been cleaned and lubricated. Building Services crews have fixed the leaky roof and are replacing the floor. Jarosik is creating a digital control system for the telescope that will allow it to be operated from a remote computer and to transmit images via the Internet.
"It will be nice to have it working again," said Groth, who used the telescope for his 1971 doctoral dissertation, in what was one of the few times it was used for serious research observations. He said the telescope will be a valuable teaching tool.
As for the OSETI project itself, Wilkinson hopes the Princeton group will begin observations this winter. He will equip the telescope with a digital device that ignores normal starlight and responds only when it detects a strong, short pulse, something on the order of a nanosecond (or a billionth of a second) in length.
Rare in nature
A key principle that makes OSETI possible is that such pulses of light are thought to be extremely rare in nature. When charged particles from space hit the Earth's atmosphere, they can produce the optical equivalent of a sonic boom, causing a nanosecond flash. Apart from this atmospheric phenomenon, which is thought to be rare, there are no known natural sources of such flashes in the universe. So if a pulse appears, and it comes from outside our atmosphere, it will be of immediate interest.
At Harvard, Horowitz began just such a search about a year ago (see mc.harvard.edu/oseti/index.html). And, amazingly, he has been detecting one or two spikes a night.
That's where Princeton comes in. The collaboration will determine if those spikes really are coming from distant stars or (as is more likely) they are caused by atmospheric interference. The Princeton and Harvard teams plan to look at the same stars at the same time. If only one of the observers sees a spike, it is probably an atmospheric effect. If both see it, then it is likely that it comes from the distant star, because the two observatories will be looking through entirely different slices of Earth's atmosphere.
"If we both see one at the same time -- wow, that will be hard to explain," Wilkinson said.
One star at a time
Wilkinson acknowledges, however, that the chances of success are slim.
"We're looking at one star at a time, and there are 100 billion stars in our galaxy," he said. Scientists have been working to narrow that list down to the most likely candidates for harboring intelligent life, but the criteria are far from clear. Horowitz and Wilkinson plan to look at about 1,000 stars over the next three years.
In addition to the sheer number of stars, there are many other problems. For instance, how do we know the universe is not full of listeners -- like us -- who don't actively send messages out into the heavens? If they are sending signals, are they pointing them at us?
Despite the odds, the possibilities are too tantalizing to ignore.
Pascal compared the SETI search to playing the lottery. "You do it even though it's hopeless -- or nearly hopeless -- because if you won it, it would change your life." Discovering extraterrestrial intelligence would have the same effect for humankind. Or, as Wilkinson says in dry understatement, "That would be a first-rate discovery for our species."