Posted on 08/18/2004 11:24:47 AM PDT by Joe Hadenuf
SETI Conference:
Planning for a Long Search
August 13, 2004 | Jodie Foster made it look so easy in the 1997 movie Contact. With giant radio telescopes having scrutinized some 800 of the nearest stars for artificial signals, and with a half million home computers churning through radio data from all across the sky, you might think that the search for extraterrestrial intelligence, or SETI, would be well along by now.
Think again. At an August 6th symposium organized by The Planetary Society, leading SETI experts stressed that we've barely scratched the surface. Guillermo Lemarchand (University of Buenos Aires) put a number on our ignorance about alien signals. A couple decades of radio searches, he described, have probed only a hundred-trillionth (0.00000000000001) of the "cosmic haystack" — the radio channels, sky directions, and other parameters that need to be searched for the "needle" of an artificial signal.
How much do we need to search before we can say there are no alien radio signals to be found? Guillermo Lemarchand estimated that we've searched only a hundred-trillionth of the "search space" that needs to be covered.
The symposium, held at Harvard University, was titled The Significance of Negative SETI Results. "There is no news," admitted Bruce M. Murray, a Caltech professor emeritus who's been involved in SETI since the 1970s. Murray chairs the board of directors for the Planetary Society, which has fostered and funded various search efforts. So is the Society's money being spent wisely?
To put the lack of signals in perspective, Murray and colleague Bruce Betts brought together most of the field's top specialists for the day-long brainstorming session. (Two notable absences were Jill Tarter, director of the nonprofit SETI Institute in California, and MIT scientist Philip Morrison, who together with Giuseppe Cocconi first articulated the possibility of interstellar radio communication in 1959.)
Far from being discouraged, the workshop's attendees frequently reminded one another that their work has just begun. "We haven't done very much," admitted Dan Werthimer (University of California, Berkeley), who has spearheaded the wildly successful SETI@home grassroots effort. "Earthlings are just getting into the game — we can't rule out hardly anything."
But Murray repeatedly pressed the panel for specifics of what has been ruled out. Frank Drake, senior scientist at the SETI Institute, responded that no alien civilization appears to be continuously broadcasting a powerful "beacon" signal from a planet circling any of the nearest 1,000 or so Sunlike stars, at least in the frequency bands we've searched. If there were such powerful beacons, they'd have been picked up by Project Phoenix, an ambitious nine-year undertaking that the SETI Institute concluded last March. (The SETI Institute's next big project, the Allen Telescope Array, is now under construction.)
Many people assume that we could eavesdrop on aliens' everyday communications. But this idea has little chance of success, said Drake. He notes that even 10-megawatt broadcasts, the most powerful on Earth, could be picked up only from stars a few light-years away using Earth's largest dish. Meanwhile our own technology is evolving toward more energy-efficient, point-to-point communications, rather than pumping ever more megawatts of radio power into the sky. "A hundred years from now," Drake predicted, "the Earth will disappear as a radio source." By extension, he says, the only aliens we're likely to hear are ones intent on deliberately signaling to emerging civilizations like us.
So how would an eager-to-talk civilization try to catch attention? One option would be to target promising stars — if not the whole Milky Way — with narrowband radio blasts. In that case, our task is to turn a radio ear toward as many stars as possible for as long as possible, listening at as many channels as possible simultaneously. Drake thinks that searching vast numbers of stars for very powerful transmitters, by wide-field sweeping, is a better bet than scrutinizing nearby stars for weaker transmitters by sensitive searches that are narrowly targeted.
Despite the lack of results so far, there's a lot of excitement in the SETI community because search capabilities are increasing by leaps and bounds. SETI capabilities are growing at about the rate of "Moore's Law," which says the amount of computing power you get per dollar doubles every 18 months. Seth Shostak, senior astronomer at the SETI Institute, recently said that if Moore's Law continues to hold true, he thinks that we'll detect an alien communique within the next two decades.
But the workshop participants were less optimistic. "Maybe within 100 or 200 years," suggested Kent Cullers, the Institute's head of research and development. "Twenty years is too soon."
"I agree," put in Werthimer. "I think maybe 50 or 100 years."
Not all SETI efforts are radio-based. Paul Horowitz and Andrew Howard of Harvard are building a 72-inch telescope west of Boston to conduct a wide-sky survey for very brief pulses of light directed Earth's way. The most powerful lasers we have designed so far can blast out a million billion watts of light for a billionth of a second. In that brief instant such a laser, aimed at our solar system through a 10-meter telescope on a distant planet, would far outshine the planet's host star. Detecting such brief pulses of light is technologically easy. The ability to do it will soon be built into high-end amateur CCD cameras.
"If they really want to contact us, they can," Horowitz said.
But, the conference participants stressed, we still don't know if we're watching or listening the right way. For instance, between radio and visible light there's a gigantic unexplored spectrum of infrared and millimeter-waves frequencies. There's reason to think these are the most efficient frequencies for interstellar communication. Perhaps the aliens have decided that anyone smart enough to be interesting will realize this, and are signaling there accordingly. But we can't search these frequencies well until we do can SETI from above Earth's atmosphere.
"Your best guess is your worst enemy," admitted Werthimer. "It's naïve to think that the searches we're doing today are the best ones." Instead, he advises, think serendipity. "We should all be looking for little glitches in our data."
It would be interesting to one day discover that attempts to contact earth have been on going for hundreds or thousands of years, but we were just not using the right mode or criteria to receive it.
This is the article I referred to. Thought you'd like to see it.
We are having a difficult enough time in our search for consistent intelligent life on this planet.
Ain't that the truth..
Maybe that's why they are looking elsewhere.
I'm still hopeful. If it happens in my lifetime it will be like Columbus discovering the new world. I started to say times 10, but that would understate the impact on the 1490's world.
I have made this very assertion here on FR many times. However, if we do move out into the solar system, IMHO, high power radio again will be employed.
Thanks for posting this. :-)
true, true
Put your ear on the railroad track. If your head is big enough use both tracks.
Be sure to look both ways before bending down.
I usually buy a bum homeless person abottle of Ripple wine and he watches for incoming. ;)
Maybe we should be looking for those. Perhaps an advanced civilization could be expected to use them in space for various reasons (not just war), construction projects, etc.
Not far at all.
Oh, rats . . . Scratch that idea, then! :-)
I didn't see where we are trying to contact anyone ourselves. Assuming there are others out there, how do we know they're not just listening, too?
Got proof?
Just as there is only one life form here on earth with creative intelligence (among literally the billions of species of living things on our planet), there is only one life form in the universe with creative intelligence: Human Beings.
In this vast universe, you know for a fact we are the only self aware tool building species?
The real search should be why God planned it that way!
He did? How do you know this? He told you?
(and quit wasting money on SETI)
That is my business what I do with my money as long as it is legal. And as far as I know, SETI is still legal.
Absolutely. Just ask the dolphins before they disappear.
You may be right. But then again, you may be very wrong. It's my opinion that there is life outside of our planet.
Let's say we were interested in faster than light communication. Obviously radio won't cut it. However, if we were to build a "string" between two very far apart points, and apply small pulls to that string, would that allow a transfer of information faster than light? Just for arguments sake, let's assume that the "string" is made of a non-elastic material (carbon nanotube?).
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