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The Search for Extra-Terrestrial Intelligence
Are we alone? It's a question that's become almost a cliché. In a universe the size of ours, it might be better to ask "How could we possibly be alone?"
TOPICS:
- Background
- How SETI Searches for Life
- SETI Organizations and Projects
- SETI@home
- What Happens If We Make Contact?
- Suggested Reading: SETI-Related Links
- How SETI Searches for Life
- BACKGROUND
- Throughout the course of human history, there has been a desire by humans of all cultures to
seek out others like us somewhere "out there." Most of this searching took the form of mythology and
even religion; witness the gods of ancient Greece and Rome, and the mythology of Egypt and South
America. As far back as Socrates and Plato, though, there have been questions about worlds like
ours in the sky, and whether those worlds might be populated by creatures similar to us. This basic
quest for that kinship is the basic drive of the Search for Extra-Terrestrial Intelligence (SETI).
It should be made clear from the very beginning that SETI should never, ever be confused with the UFO phenomenon or the culture that has sprung up around it. The SETI project is a scientific quest, and the scientists and volunteers at its core are mostly physicists, chemists and electronics engineers. These people, on the whole, are skeptical—even contemptuous—of those who would assert that little green (or grey) men in flying saucers have ever visited our planet. To be blunt, it doesn't work. At the fastest speeds our current space probes move, it would take approximately 82,000 years to reach the nearest star. Granted, this is with current technology and any space-faring civilization would by necessity have better technology, but the physics simply make such long journeys highly improbable. Only energy travels at the speeds necessary for intragalactic travel, and even at the speed of light (the fastest speed possible in conventional physics) travel between stars would still be impractical. Physicists, on the whole, are also skeptical of New Age concepts like "interdimensional beings" and "astral projection." Regardless of how "scientific" the proponents of these ideas like to say they are, these are not scientific concepts. (They could be lumped into "philosophy" if you wanted to be charitable, but they more appropriately belong in the category of mythology.) In short, the SETI project is a project run by credible, hard-core scientists using applicable technologies to conduct a scientific search for an answer to the ultimate question: is there anyone else out there?
The obvious questions that come to mind are, "Why search? And if we are going to search for life, why not search for simple life—like bacteria—rather than intelligent life, which (if it exists) is much more rare?"
The first question is the most difficult question to answer. Perhaps the best answer is, "Because it's our nature as human beings." Beyond the obvious technological advances we could achieve through interaction with another intelligent species—divergent evolutions resulting in divergent theories and technologies—there's a deeper desire within the human species to reach out and find kinship from someplace beyond our own world. Such a discovery would shake the foundations of our religions, our philosophies, our cultures and quite possibly our lives as individuals.
The second question is much easier to answer because it's a nuts-and-bolts question that involves practical issues. Yes, we suspect there may be other life in the universe, although we haven't proven it yet. And, yes, most of that life will probably be in the form of simple bacteria-like organisms. (We should be very careful not to list any extraterrestrial life under terrestrial taxonomy.) We might even find life that would be like plants or animals. Some of it might even resemble (in some ways) more complex forms of life found on Earth: fish, insects, etc. Intelligent life—defined for our purposes as living creatures capable of manipulating their environments and creating artificial structures and devices—would be rare, indeed (or so we believe). But these forms of life would still be easier to find than the less complex life out there. In order to find non-sentient life beyond the Earth, we would have to travel to whatever world it calls its home. Intelligent life, on the other hand, would most likely develop technologies similar to our own for communication. This means that they will eventually start broadcasting radio waves into space where they can be detected. In other words, sentient life would (intentionally or not) come to us. Therefore, the search for extraterrestrial intelligence may actually yield evidence of life on other worlds before any other search. And what a coup! To discover not only life, but intelligent life, all at once! How incredible!
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- HOW SETI SEARCHES FOR LIFE
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Because we currently believe that the best means of detecting intelligent life is through listening,
the SETI project searches through the use of radio telescopes to scan the skies for artificial signals.
(Just like in the movie
Contact.)
How do we know if these signals are artificial? There are two ways to tell.
The first way to tell is by looking at the bandwidth in which you find the signal. The universe is a very noisy place in terms of radioactivity. Every single star and every single reaction that takes place in space generates radio waves (which is why sunspots can cause problems for wireless communication at times). There is a small window of frequencies (between 1,000 to 100,000 mHz) where very little natural background noise is present. It is in this band—the microwave band—that we send out wireless signals for broadcast and communication. It is quite logical, then, to assume that because this is the "quiet" portion of the spectrum, that (1) extraterrestrial technologies would broadcast in this band, and (2) that any signal detected in this band that is significantly stronger than the background radiation is likely artificial in nature. So, if we detect a signal in that bandwidth and it's determined not to be from a terrestrial source, we have our first clue that this might be a signal produced by extraterrestrial intelligence.
The other way to determine if the signal is of artificial origin is to look for the presence of a carrier wave. This is where it all gets technical, but essentially you have to find a frequency that is transmitting information, not just random static. Such information would likely create a pattern of some sort. This is the part where distinguishing a natural signal from an artificial signal gets tricky. It was a SETI project, in fact, that led to the discovery of pulsars.
Pulsars are very dense, very old stars that have collapsed in on themselves. They spin at an extremely high rate of speed, and spew forth large amounts of radio waves from specific locations on their surface. Because they are rotating at a very precise rate, these radio emissions come in very regular bursts. Astronomers at Cambridge University detected these radio bursts in 1967, and at first assumed them to be of terrestrial origin because of their strength and the precise pattern of the bursts. When it was confirmed that the energy was coming from a non-terrestrial source, there began a buzz that evidence of extraterrestrial life had been found. This was, of course, proven not to be the case. (More information on pulsars can be found on the Princeton Physics Department website and at the University of Cambridge.)
It does serve to highlight the technical dilemma in distinguishing natural signals from artificial signals. The signal should be regular, but not so regular as to indicate that it is originating from a pulsar or pulsar-like body. It should be significantly stronger than the background noise of the universe. It should also appear to at least have the capacity for conveying some kind of information. These are all very tricky, very "fuzzy" kinds of criteria, and it takes significant computing power to find likely candidates. There have been very few detections that have met all these criteria, and nearly all have been determined to have come from terrestrial radio sources or from orbiting satellites (including spy satellites that the Air Force thought were undetectable). The most famous possible "hit" came from the Big Ear Radio Observatory (Ohio State University) in 1977. The "WOW! signal" made headlines when it inexplicably created a spike in the observatory's readings. The signal has been confirmed to have been genuine, and not simply an atmospheric trick or an instrument malfunction. However, it is still possible that the WOW! signal could have resulted from a terrestrial broadcast reflecting from a piece of space debris or a malfunctioning satellite.
So, then, we are searching the universe for radio signals with radio telescopes. Unlike optical telescopes, which allow the human eye to see objects very far away, radio telescopes detect radio frequency (RF) radiation. The most famous of these radio telescopes is the gigantic observatory in Arecibo, Puerto Rico. Unlike Arecibo's giant dish, however, most radio telescopes are actually assemblies of dishes, all synchronized to magnify the signals coming from a particular point in the sky. The radio telescope listens to the "noise" in the particular band it is monitoring (the exact amount of bandwidth covered varies from observatory to observatory) and then analyzes it, looking for signals that stick out against the background and match the criteria for an artificial, extraterrestrial signal.
Seems easy enough. Problem is, the universe is huge. And there's a lot of bandwidth to cover in the relatively narrow microwave range. According to H. Paul Shuch, Executive Director of the SETI League, the typical research grade radio telescope covers only one one-millionth of the sky at any given time. This means that even if a radio telescope was monitoring the sky at exactly the right time on exactly the right frequency when an extraterrestrial signal came in, there would be a 99.9999% chance that the telescope would not pick it up (see also "How Many Dishes?" by H. Paul Shuch). Bear in mind that these telescopes are not dedicated solely to SETI research. In fact, SETI projects actually beg for time between other important research projects into pulsars, black holes, novae and other astronomical phenomenon. It is a daunting task, but one that (with new technologies and new strategies) should prove worthwhile.
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- SETI ORGANIZATIONS AND PROJECTS
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The SETI Project is actually a collection of projects, each run independently by separate
organizations. SETI is a worldwide endeavour, with observatories on every continent except
Antarctica. There are also thousands of amateur radio astronomers involved in the SETI project
in one way or another. While these projects sometimes differ in their approaches and methods,
they are all guided by the same principle: a dedication to finding credible, scientific evidence
of life in the universe. Since the equipment used in this search is so specialized and observatory
time is always a premium, it is not unusual for two or more independent organizations to work
together on a project, or in validating data. Some of the more prominent SETI organizations and
projects include:
• BETA Project (Harvard University)
• The Planetary Society
• The SETI League, Inc.
• Project Argus
• The SETI Institute
• Project Phoenix (The SETI Institute)
• Project SERENDIP (U.C. Berkeley)
• Project BAMBI (Amateur SETI Project)
• The Contact Project (Lunar Institute of Technology)
• SETI Systems Laboratory
• Project Argus
• SETI Australia Centre (University of Western Sydney Macarthur)
• The Columbus Optical SETI Observatory
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- SETI@home
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Radio telescopes obtain a tremendous amount of data with each sweep of the sky. Analyzing this data
takes computing power—a lot of computing power. This eats up valuable (and expensive!)
computer time, and it makes analyzing data cumbersome and difficult. Project SERENDIP,
one of the largest SETI projects currently underway, is expecting to generate a massive amount of data—one megabyte every four minutes—for analysis.
Even with the SERENDIP IV system, essentially a 200 billion-instructions-per-second supercomputer, this data takes a great
amount of time to analyze. To get around this, Project SERENDIP is initiating a "distributed computing" project called
SETI@home.
The "distributed computing" model works on the principle that a thousand small computers working simultaneously can do the work of one gigantic computer in less time. Small packets of data are fed to each computer. These packets are analyzed and the results sent back to the hub, where a new batch of raw data is downloaded and so on.
SETI@home uses this principle as a means of analyzing the vast amounts of data Project SERENDIP receives from its observations at Arecibo Observatory. Volunteers download a simple screen saver from the SETI@home site and install it on their home computers. When the computer is idle and the screen saver is activated, it begins analyzing data from Project SERENDIP in the background. Then, when the analysis is complete, the results are packaged for uploading. Upon the next internet connection, SETI@home uploads the processed data to the SERENDIP mainframe and downloads the next packet of raw data. Since the program only runs when the screen saver activates, the user doesn't even notice it's there. This is a brilliant way to not only do valuable work, but to also allow SETI enthusiasts who might not otherwise be capable of involvement in the search a means to contribute in a meaningful way.
For more information on SETI@home, see the MSNBC report on SETI@home.
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- WHAT HAPPENS IF WE MAKE CONTACT?
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The goal of the SETI project is to find intelligent life on other planets, of course. Assuming
that such life is found (and nobody really expects this to happen within our lifetimes), what happens?
Do we keep it a secret to avoid public panic? Under whose jurisdiction does this information fall?
And do we respond? If we respond, how do we respond? Do we try to intimidate our neighbors
into leaving us alone, or do we invite them to come to our planet for a nice spot of tea?
These are legitimate questions, and they have been addressed by organizations participating in the SETI project. The Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence describes in exact detail the steps that an astronomer should take if (s)he detects an extraterresrial signal. First, the information is reported to the Central Bureau for Astronomical Telegrams of the International Astronomical Union so that other astronomers can verify the signal. The information is also presented to the Secretary General of the United Nations in accordance with Article XI of the "Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Bodies." The discoverer has to share any and all information about the signal with the scientific community to validate the claim, and then the discoverer gets the extreme privilege of addressing the media to make the most important announcement in human history: that we are not alone. There is life out there.
A separate document, entitled IAA Position Paper: A Decision Process for Examining the Possibility of Sending Communications to Extraterrestrial Civilizations addresses the issue of sending a reply to any messages we receive. As the report says, "the issues involved in sending messages to extraterrestrial civilizations raise profound philosophical and political questions. These questions are of such weight for the future of our own civilization as to merit extensive discussion, perhaps over a period of many years." Indeed. What if the aliens are hostile? What if they are on a religious quest to convert us? Will their morality and our morality conflict, leading to unpleasantness and war? Human history is awash in examples of relatively primitive cultures meeting with more advanced cultures, and the end result is almost always the destruction of the more primitive culture. What if our entire planet is the more primitive culture?
While the IAA Position Paper does not lay out the steps for a process, it does lay the groundwork, putting forth three principles that must be observed when creating this process:
1.The decision on whether or not to send a message to extraterrestrial intelligence should be made by an appropriate international body, broadly representative of Humankind.
2.If a decision is made to send a message to extraterrestrial intelligence, it should be sent on behalf of all Humankind, rather than from individual States or groups.
3.The content of such a message should be developed through an appropriate international process, reflecting a broad consensus.
Based on these three principals, the "Draft Declaration of Principles Concerning Sending Communications with Extraterrestrial Intelligence" is currently being written. It will be interesting to see the final results. What are your thoughts on this subject? It is a topic which interests me greatly, and I would love to hear from you on this via email.
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- SUGGESTED READING: SETI-RELATED LINKS
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The following links offer just a glimpse of the SETI-related
references available on the internet. I have found each to be informative and useful. If you find
any links worthy of addition to this list, please email them to me.
The SETI League, Inc.
Project Argus
The SETI Institute
Project Phoenix (The SETI Institute)
The Drake Equation (calculates the odds of intelligent life)
SETI Institute FAQ
General SETI Information (The SETI Institute)
SETI Institue: Science Behind Contact
The Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence
IAA Position Paper: A Decision Process for Examining the Possibility of Sending Communications to Extraterrestrial Civilizations
Project SERENDIP (U.C. Berkeley)
SETI@home
MSNBC report on SETI@home
SETI Australia Centre (University of Western Sydney Macarthur)
Big Ear Radio Observatory
Beginner's Guide to Radio Telescopes and SETI (Excellent!)
The Big Ear "WOW!" Signal
Big Ear's Information on SETI (Excellent!)
BETA Project (Harvard University)
The Planetary Society
Project BAMBI (Amateur SETI Project)
The Contact Project (Lunar Institute of Technology)
SETI Systems Laboratory
The Columbus Optical SETI Observatory
Princeton Physics Department
University of Cambridge (U.K.)
Paddy Carroll's SETI Information
