Alien cultures more advanced than our own have spotted us by now, say astronomers. Within 15 years, our own next-generation telescopes will be searching the skies for the tell-tale rainbows from inhabited planets.

?Our own Earth has been putting out a signal for a billion years,? says astronomer Roger Angel of the University of Arizona in Tucson. ?Any civilization slightly more advanced than our own would know there was life on this planet.?

Astronomers expect that planets with life will resemble Earth. ?We have to look for what we understand,? says molecular biologist Norman Pace of the University of Colorado. The spectrum of wavelengths in light sent out from a distant planet should reveal signs of life. Bright blue suggests an Earth-like atmosphere of gases, while green plants reflect red light. Life-supporting gases such as oxygen and nitrogen absorb certain infrared wavelengths.

The overall color to look for is purplish, says Wesley Traub of the Harvard Smithsonian Center for Astrophysics. ?We?d feel fairly convinced there?s something going on there,? he says.

We don?t yet have telescopes that can pick up these giveaway beams, since the faint light reflected by planets is drowned out by their bright suns. But powerful future devices that can pick up these indicators are already being planned. Huge arrays of telescopes called interferometers will function like a giant mirror. By focusing faint light, they should be able to distinguish planet light from the light of a nearby star.

NASA?s four-telescope Terrestrial Planet Finder is scheduled for launch by 2013, and the European Space Agency?s six-telescope Darwin interferometer will be launched in 2015.

But even if we find a planet with life, it will be too far away for us to travel there, although we may be able to send messages back and forth.

For more information,click here.

Astronomer Frank Drake, the Father of SETI, believes that extraterrestrials will be altruistic, rather than malevolent. Drake reasons that if they were hostile, their civilizations wouldn?t have lasted long enough for them to develop the technology to make contact with us. Only extraterrestrials with a long-lasting, stable society will be around long enough to be detected by our SETI programs.

SETI wants to figure out how our view of ourselves affects our beliefs about extraterrestrials. Using the responses to their internet survey, and analyzing these data with some basic statistics, they learned that there is a significant correlation between these two attitudes. The more anthropocentric (human-centered) a person is, the less likely they are to believe that life exists beyond Earth. In other words, if we see everything in the world around us (and in other worlds) in terms of what we, as human beings, think and feel?and if what we think and feel is sometimes pretty negative?then we?re likely to think that any aliens who have arrived are evil.

They also found a very strong connection between people?s beliefs about extraterrestrials and their feelings about how meaningful life is. When someone is confronted with ambiguous information, what he or she makes of the information can sometimes say a lot about the person. It?s what psychologists call ?projection??when you project your own thoughts and feelings onto others and decide that?s the way they think and feel.

If our telescopes ever do pick up signs of intelligent life beyond Earth, it will take time to understand what these extraterrestrials are trying to say. Thus, it?s likely that we?ll know that ETs exist long before we know what they might be trying to tell us.

In the face of missing information, people have a tendency to fill in the blanks. They tend to form opinions based on their own ways of seeing life. In their internet survey, SETI tested the hypothesis that if people feel like the world is cold and cruel, they?re more likely than other people to imagine extraterrestrials as being cold and cruel as well. They set up the survey to measure two things. First, to what extent do people feel ?alienated,? and second, how hostile do these people imagine extraterrestrials would be?

They reviewed the research literature in psychology and sociology to find an existing method to assess how alienated people feel. The Margins of Society Alienation Scale was described by Robert Travis in the journal Social Indicators Research in 1993. This scale measures people?s feelings of alienation by asking them to respond to the following statements:

– I feel all alone these days.- My whole world feels like it?s falling apart.- I wish I were somebody important.- It?s hard for me to tell just what is right and wrong these days.- I don?t like to live by society?s rules.- I often feel discriminated against.- I?ll never find the right person to care enough about me.

SETI asked each participant in the survey to indicate how strongly they agreed or disagreed with each statement, which gave them a way to identify people who were feeling very alienated, those who didn?t feel alienated at all, and those who fell somewhere between those extremes. While no single statement can capture a person?s overall feelings of alienation, as a group, these statements reveal a lot.

To assess people?s beliefs about how hostile aliens are likely to be, SETI used a set of statements that psychologist Yuh-shiow Lee developed. They asked people who completed the survey to imagine that we had received a radio signal with a message from intelligent life in outer space. They were then asked to rate how strongly they agreed or disagreed with each of the following statements on a six point scale. If they agreed completely, it was a ?1,? if they disagreed totally, it was a ?6.? If they were somewhere in between, they were to choose an appropriate number. Here are the statements:

– ETs are probably looking for planets they can take over for themselves.- We should not reply to the message from ETs because they might be hostile.- ETs would probably look at humans like we are nothing more than animals that belong in their zoos.- Humans would probably not be able to understand the message from ETs because humans and ETs are just too different.- If we reply to the message from ETs, they might come to Earth and take over our world.- We should not believe what the message says, because the ETs may be lying.- ETs would probably want to make humans their slaves.- The message from ETs may contain a hidden message that could be harmful to humans.

SETI added up people?s total scores for all the items in the scale, then calculated their average score for the scale. People with average ratings near 6 thought extraterrestrials would be very hostile. People with ratings near 1 were not concerned at all about ETs being evil.

If some day SETI succeeds in detecting a signal from extraterrestrials, it will be necessary to understand how our own biases could distort our interpretation of the data, so we will be able to remain as objective as possible. Humankind will face many important decisions upon detecting ETs, such as whether or not we should reply. It would be unfortunate if those decisions were based on personal prejudice instead of well-reasoned analysis.

To learn more about the SETI survey,click here.

Sgt. Clifford Stone will be on Dreamland February 23. To learn about his contact experiences,click here.

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