SETI Contact
Could Planet Earth be the only Planet that is Full of Life?

SETI (Search for Extraterrestrial Intelligence) is a scientific area whose goal is to detect intelligent life outside Earth. One approach, known as radio SETI, uses radio telescopes to listen for narrow-bandwidth radio signals from space. Such signals are not known to occur naturally, so a detection would provide evidence of extraterrestrial technology.

Radio telescope signals consist primarily of noise (from celestial sources and the receiver's electronics) and man-made signals such as TV stations, radar, and satellites. Modern radio SETI projects analyze the data digitally.

More computing power enables searches to cover greater frequency ranges with more sensitivity. Radio SETI, therefore, has an insatiable appetite for computing power. Previous radio SETI projects have used special-purpose supercomputers, located at the telescope, to do the bulk of the data analysis.

In 1995, David Gedye proposed doing radio SETI using a virtual supercomputer composed of large numbers of Internet-connected computers, and he organized the SETI@home project to explore this idea. SETI@home was originally launched in May 1999.

The second of these goals is generally considered to have succeeded completely. The current BOINC environment, a development of the original SETI@home, is providing support for many computationally intensive projects in a wide range of disciplines.

The first of these goals has failed to date: no evidence for ETI signals has been shown via SETI@home. However, ongoing continuation is predicated on the assumption that the observational analysis is not an 'ill-posed' one.

SETI@home searches for possible evidence of radio transmissions from extraterrestrial intelligence using observational data from the Arecibo radio telescope.

The data are taken 'piggyback' or 'passively' while the telescope is used for other scientific programs. The data are digitized, stored, and sent to the SETI@home facility. 

The data are then parsed into small chunks in frequency and time, and analyzed, using software, to search for any signals—that is, variations which cannot be ascribed to noise, and contain information.

The crux of SETI@home is to have each chunk of data, from the millions of chunks resulting, analyzed off-site by home computers, and then have the software results reported back.

Thus what appears an onerous problem in data analysis is reduced to a reasonable one by aid from a large, Internet-based community.

The two original goals of SETI@home were:

to do useful scientific work by supporting an observational analysis to detect intelligent life outside Earth, and
to prove the viability and practicality of the 'volunteer computing' concept.

The Search for Life: The Drake Equation
An Equation used to Estimate the Number of Detectable Extraterrestrial Civilizations in the Milky Way Galaxy

In 1960, Frank Drake conducted the first search for radio signals from extraterrestrial civilizations at the National Radio Astronomy Observatory in Green Bank, West Virginia.

Soon thereafter, the National Academy of Sciences asked Drake to convene a meeting on detecting extraterrestrial intelligence.

The meeting was held at the Green Bank facility in 1961.

The equation that bears Drake's name arose out of his preparations for the meeting:

As I planned the meeting, I realized a few days ahead of time we needed an agenda. And so I wrote down all the things you needed to know to predict how hard it's going to be to detect extraterrestrial life. And looking at them it became pretty evident that if you multiplied all these together, you got a number, N, which is the number of detectable civilizations in our galaxy. This, of course, was aimed at the radio search, and not to search for primordial or primitive life forms.
– Frank Drake

This meeting established SETI as a scientific discipline. The meeting's dozen participants — astronomers, physicists, biologists, social scientists, and industry leaders — became known as the "Order of the Dolphin".

The Green Bank meeting has been commemorated by a plaque at the site. The Drake equation is closely related to the Fermi paradox in that Drake suggested that a large number of extraterrestrial civilizations would form, but that the lack of evidence of such civilizations (the Fermi paradox) suggests that technological civilizations tend to disappear rather quickly.

This theory often stimulates an interest in identifying and publicizing ways in which humanity could destroy itself, and then counters with hopes of avoiding such destruction and eventually becoming a space-faring species.

A similar argument is The Great Filter, which notes that since there are no observed extraterrestrial civilizations, despite the vast number of stars, then some step in the process must be acting as a filter to reduce the final value. According to this view, either it is very hard for intelligent life to arise, or the lifetime of such civilizations must be relatively short.

Carl Sagan, a great proponent of SETI, quoted the formula often and as a result the formula is sometimes mislabeled as "The Sagan Equation."

Seth Shostak on SETI
The Search for Extra Terrestrial Intelligence

Seth Shostak (born July 20, 1943) is an American astronomer. He earned his physics degree from Princeton University and a Ph.D. in astronomy from the California Institute of Technology.

He is the Senior Astronomer at the SETI Institute in Mountain View, California, and the 2004 winner of the Klumpke-Roberts Award awarded by the Astronomical Society of the Pacific in recognition of his outstanding contributions to the public understanding and appreciation of astronomy.

Before his involvement with SETI research, he used radio telescopes in the USA and the Netherlands, searching for clues to the ultimate fate of the universe by analyzing galaxy motion.

While working at the University of Groningen, the Netherlands, in his spare time he also founded and ran a computer animation company called DIGIMA.

He hosts the SETI Institute's radio program 'Are We Alone?'. Each week, Shostak interviews guests about the latest scientific research on a variety of topics: cosmology, physics, genetics, paleontology, evolutionary biology and astrobiology, and once a month hosts "Skeptic Check", a show focused on debunking pseudo-science, U.F.O.s and practices such as astrology and dowsing.

Are We Alone? is available for download at the SETI Institute's website and through podcasts.

His hobbies include photography, filmmaking, and electronics.Shostak presented twelve 30-minute lectures on audio-tape and video titled "The Search for Intelligent Life in Space" for the Teaching Company in 1999.

He has been an observer for Project Phoenix (SETI) as well as an active participant in various international forums for SETI research.

He is also Chair of the International Academy of Astronautics SETI Permanent Study Group. Dr. Shostak has been nominated by the SETI Institute to be one of the USA Science and Engineering Festival's Nifty Fifty Speakers who will speak about his work and career to middle and high school students in October 2010.

The Search for Extraterrestrial Intelligence at Home
Discover ET Using Your Home Computer

SETI@home ("SETI at home") is an internet-based public volunteer computing project employing the BOINC software platform, hosted by the Space Sciences Laboratory, at the University of California, Berkeley, in the United States.

SETI is an acronym for the Search for Extra-Terrestrial Intelligence. Its purpose is to analyze radio signals, searching for signs of extra terrestrial intelligence, and is one of many activities undertaken as part of SETI.

SETI@home was released to the public on May 17th, 1999, making it the second large-scale use of distributed computing over the Internet for research purposes, as was launched in 1997.

Along with Milkyway@home and Einstein@home, it is the third major computing project of this type that has the investigation of phenomena in interstellar space as its primary purpose.

The software searches for four types of signals that distinguish them from noise:

  • Spikes in power spectra
  • Gaussian rises and falls in transmission power, possibly representing the telescope beam's main lobe passing over a radio source
  • Triplets — three power spikes in a row
  • Pulsing signals that possibly represent a narrowband digital-style transmission

There are many variations on how an ETI signal may be affected by the interstellar medium, and by relative motion of its origin compared to Earth. The potential 'signal' is thus processed in a number of ways (although not testing all detection methods nor scenarios) to ensure the highest likelihood of distinguishing it from the scintillating noise already present in all directions of outer space.

For instance, another planet is very likely to be moving at a speed and acceleration with respect to Earth, and that will shift the frequency, over time, of the potential 'signal'. Checking for this through processing is done, to an extent, in the SETI@home software.

The process is somewhat like tuning a radio to various channels, and looking at the signal strength meter. If the strength of the signal goes up, that gets attention. More technically, it involves a lot of digital signal processing, mostly discrete Fourier transforms at various chirp rates and durations.

Search for Extra-Terrestrial Intelligence
Movie - Contact

- Our airwaves are sending out signals throughout the galaxy. During the early years many scientists thought that these airwaves would travel beyond our known universe preserved in perfect condition but now many scientists feel that they will be distorted due to many factors.

Either way, we are still sending out signals from our airwaves to other points throughout the galaxy. Maybe one day we will get a reply from an alien race. Some people feel we already have but our governments will not disclose such information to the mass public in fears of social and economic collapses.

Some individuals and groups believe that the Wow! signal was such a
response from an unknown species.

The Wow! signal was a strong narrowband  radio signal detected by Dr. Jerry R. Ehman on August 15, 1977, while working on a SETI project at The Big Ear radio telescope of Ohio State University.

The signal bore expected hallmarks of potential non-terrestrial and non-solar system origin. It lasted for a total of 72 seconds, the full duration Big Ear observed it, but has not been detected again. Much attention has been focused on it in the media when talking about SETI results.

Amazed at how closely the signal matched the expected signature of an interstellar signal in the antenna used, Ehman circled the signal on the computer printout and wrote the comment "Wow!" on its side. This comment became the name of the signal.