I see that SETI@home is concerned about being able to continue its matching funds program from the University of California and is actively soliciting donations. It’s a terrific project, of course, and the numbers are staggering: with early expectations of raising 100,000 participants, SETI@home wound up with 5.4 million volunteers who donated 2.4 million years of processing time. A new data recorder at Arecibo and juiced up operating software make the program more potent than ever, and certainly worthy of support.
Also on the SETI front is the Planetary Society’s dedication of the first telescope exclusively devoted to optical SETI (OSETI). The Harvard-based observatory includes a 72-inch primary mirror that is larger than any U.S. optical telescope east of the Mississippi. Performing one trillion measurements per second and expanding existing optical searches by 100,000-fold, the new installation will search for laser signals that can far outshine the light of a nearby star even with today’s technology.
Here’s more on just how visible such signals might be (via the Princeton Optical SETI project:
Light coming from a star alone filtered to one part in 10,000 amounts to 4 Joules of energy every nanosecond. Therefore, a laser signal coming from near the star must exceed 4 Joules within a nanosecond in order for it to outshine the star. Modern lasers designed for nuclear fusion can exceed this power requirement by some 300,000 times… Even if the exact frequency of transmission is unknown, such a laser would still outshine the sender’s star by 30 times during the nanosecond pulse without any filtering.
All this is exciting stuff, even for those of us whose deep suspicion is that while life is abundant — perhaps ubiquitous — in the universe, technological civilizations are vanishingly rare. For let’s face it, everything we can surmise about extraterrestrial civilizations is based on our own assumptions as a species. We have no idea whether an advanced civilization would attempt to contact other less developed cultures, or for what reason, but we will never be sure that a bright beacon isn’t pumping terabytes of galactic know-how to us every second unless we look.
Optical SETI is particularly intriguing because a laser signal’s high frequencies can carry vast amounts of information. But the history of the concept was low-bandwidth indeed. The first optical SETI proposal I am aware of came from the German mathematician Karl Gauss (1777-1855), who proposed using a system of light and mirrors to send a signal to the Moon (not Mars, as I misstated in my book). Gauss seems to have influenced Joseph von Littrow (1781-1840), director of the Vienna Observatory, who attributed his suggestion of filling ditches with kerosene and lighting them as a celestial beacon to a ‘German geometer’ (I owe this information to Brett Holman at the University of Melbourne, in what turned out to be a very helpful e-mail).
In more recent times, the classic 1959 paper by Giuseppe Cocconi and Philip Morrison discussed using masers for communication, operating with microwaves rather than visible light. It was Charles Townes’ ongoing work on the laser that suggested to him that the optical spectrum be used for the SETI hunt. The variety of OSETI attempts that have followed rely on the key advantages of laser communications, not only the high bandwidth but the fact that interference from natural sources is more of a problem with microwaves than visible frequencies. And as far as we know, nanosecond pulses of light do not occur in nature, making their creation a probable technological event.
The Morrison and Cocconi paper is “Searching for Interstellar Communications” (Nature 184, no. 4690 (September 19, 1959): 844-46. For those of us who collect key scientific papers, this one is still a thing of beauty. Charles Townes’ paper on using visible light was written with R.N. Schwartz; it’s “Interstellar and Interplanetary Communication by Optical Masers,” Nature, 190, no. 4772 (April 15, 1961): 205-208.
SETI@home ramps up to analyze more data in search
of extraterrestrial intelligence
1/2/08 – File #17714
Contact: Robert Sanders
1-510-643-6998
rsanders@berkeley.edu
FOR IMMEDIATE RELEASE
Berkeley — The longest-running search for radio signals from alien
civilizations is getting a burst of new data from an upgraded Arecibo telescope,
which means the SETI@home project needs more desktop computers to help crunch
the data.
Since SETI@home launched eight years ago, the project based at the University of
California, Berkeley’s Space Sciences Laboratory has signed up more than 5
million interested volunteers and boasts the largest community of dedicated
users of any Internet computing project: 170,000 devotees on 320,000 computers.
Yet, new and more sensitive receivers on the world’s largest radio telescope in
Arecibo, Puerto Rico, and better frequency coverage are generating 500 times
more data for the project than before. The SETI@home software has been upgraded
to deal
with this new data as the search for extraterrestrial intelligence (SETI) enters
a new era and offers a new opportunity for those who want to help find other
civilizations in the universe.
“The next generation SETI@home is 500 times more powerful then anything anyone
has done before,” said project chief scientist Dan Werthimer. “That means we are
500 times more likely to find ET than with the original SETI@home.”
According to project scientist Eric Korpela, the new data amounts to 300
gigabytes per day, or 100 terabytes (100,000 gigabytes) per year, about the
amount of data stored in the U.S. Library of Congress. “That’s why we need all
the volunteers,” he said. “Everyone has a chance to be part of the largest
public participation science project in history.”
The 1,000-foot diameter Arecibo dish, which fills a valley in Puerto Rico, is
part of the National Astronomy and Ionosphere Center operated by Cornell
University with funds from the National Science Foundation. Since 1992,
Werthimer and his
team have piggybacked on radio astronomy observations at Arecibo to record
signals from space and analyze them for patterns that could indicate they were
transmitted by an intelligent civilization.
When the team’s incoming data overwhelmed its ability to analyze it, the
scientists conceived a distributed computing project to harness many computers
into one big supercomputer to do the analysis. Since SETI@home was launched,
other distributed computing projects have arisen, from folding@home to predict
the three-dimensional tangle of a protein to the newly-launched cosmology@home
to model possible universes. Most are now on a platform called BOINC (Berkeley
Open Infrastructure for Network Computing), which was developed by SETI@home’s
director David Anderson so that the various projects could share resources.
“There are now 42 projects on BOINC, and, until now, there has been enough
computing power to go around,” Werthimer said.
What triggered the new flow of data was the addition of seven new receivers at
Arecibo, which now allow the telescope to record radio signals from seven
regions of the sky simultaneously instead of just one. With greater sensitivity
and the ability to detect the polarization of the radio signals, plus 40 times
more frequency coverage, Arecibo is set to survey the sky for new radio sources.
These improvements also prime the telescope for an improved search for
intelligent signals from space.
“The multiple receivers help us weed out interference better and make us less
susceptible to thinking that things terrestrial are extraterrestrial,” Werthimer
said.
Werthimer noted that, despite the fact that UC Berkeley has been analyzing radio
signals from space since 1978 on various telescopes, no telltale signals from an
intelligent civilization have yet been found.
“Earthlings are just getting started looking at the frequencies in the sky;
we’re looking only at the cosmically brightest sources, hoping we are scanning
the right radio channels,” he said. “The good news is, we’re
entering an era when we will be able to scan billions of channels. Arecibo is
now optimized for this kind of search, so if there are signals out there, we or
our volunteers will find them.”
SETI@home has been funded by various organizations over the years, including the
Planetary Society and Sun Microsystems, and continues to be supported by
individual donations from its volunteers.
###
NOTE: Dan Werthimer can be reached at 1-510-642-6997 or danw@ssl.berkeley.edu.
Eric Korpela is at 1-510-643-6538 or korpela@ssl.berkeley.edu. David Anderson is
at 1-510-642-4921 or davea@ssl.berkeley.edu.
Giuseppe Cocconi, who co-wrote the paper that is considered the start
of the modern SETI era, died on November 9 (Carl Sagan’s birthday,
ironically enough) at age 94.
His bio from CERN is here:
http://cdsweb.cern.ch/record/1142555
In 1959, Cocconi along with Philip Morrison (who narrated the short film
The Powers of Ten among other things) wrote a paper for Nature on
searching for radio signals from alien intelligences, especially along the
hydrogen line (1420 megahertz) region of the radio spectrum, where it
is relatively quiet. Since it was assumed anyone with enough knowledge
about astronomy and the right technology would know this universal
fact as well, the “Water Hole” as it was called could be a good place to
make such a signal obvious anywhere in the galaxy.
You can see and read the original paper here:
http://www.coseti.org/morris_0.htm
According to this history, Cocconi first came to Morrison with the idea
that ETI might use gamma rays to signal others across space:
http://www.planetary.org/explore/topics/seti/seti_history_02.html
The final quote in their Nature paper still says it best about SETI:
“The reader may seek to consign these speculations wholly to the domain of science-fiction. We submit, rather, that the foregoing line of argument demonstrates that the presence of interstellar signals is entirely consistent with all we now know, and that if signals are present the means of detecting them is now at hand. Few will deny the profound importance, practical and philosophical, which the detection of interstellar communications would have. We therefore feel that a discriminating search for signals deserves a considerable effort. The probability of success is difficult to estimate; but if we never search the chance of success is zero.”