Question: If extraterrestrial aliens searched the heavens looking for beings like us, could they find us? Wouldn't it be like locating a needle in a haystack?

Answer: Imagine a civilization somewhere in our Milky Way galaxy being told to look in the direction of our Sun out of the 400 billion or so stars in the galaxy, to try to pick up signs of intelligent life, poses Case Western Reserve University's Lawrence Krauss in "The Physics of Star Trek."

Knowing where to look would be quite a clue. Would it be enough? Life has existed on Earth for much of its 4.5 billion year history, but only in the last 50 years have humans been transmitting telltale signals into space, and only in the last 25 years have our radiotelescopes beamed out sufficiently powerful signals to beacon our presence.

"Assuming an alien civilization chose to make its observation at some random time during Earth's history, the possibility of discovering us would be about 1 in 100 million. And that's if they knew exactly where to look!"

Our own searches face similar obstacles. So far, our radio probes have scrutinized fewer than a thousand stellar habitats, says Seth Shostak of the SETI Institute - "Search for Extraterrestrial Intelligence." Larger sweeps of the sky may lack sufficient sensitivity to pick up signals.

It's also possible we're not listening at the right frequencies or at the right time. "But the real bottom line is that SETI is still a small effort,

http://www.pasadenastarnews.com/ci_12764909

merci a grandpas

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