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No Intelligent Aliens -- Yet
Really. Where are all the aliens? We should have been probed, exterminated, assimilated, infected, invaded or abducted by now, shouldn't we?
The Fermi Paradox ponders the lack of evidence of another transmitting intelligent civilization -- of all the stars and all the galaxies in the universe, you'd think one intelligent alien race would have bothered to call by now? Either we're on the interstellar "do not call" list, or we're the most advanced life form out here (scary thought), or (even scarier) we're the only life form out here.
The search for any extraterrestrial life is one of the most profound things we, as a species, can do. But as any other life beyond Earth's shores has yet to be discovered, the search for extraterrestrial intelligence (SETI) can be a hard-sell. Still, the search continues and scientists are thinking up more and more extreme ways to fine-tune our high-tech array of astronomical instruments to detect intelligence in the stars.
Here are the weird and wonderful ways scientists hope to snare an intelligent alien.
Kepler's SETI CandidatesSlide 2 of 27
Kepler's SETI Candidates
The main assumption we have to make is that our hypothetical alien neighbors have evolved in a similar way to us. Because there's a lack of other examples in the cosmos (so far) it's a pretty good place to start and a logical assumption to make -- even though it might be wildly improbable. I'm skeptical that any other galactic race evolved through the "reality TV phase."
One phase of development we assume is that an intelligent race of aliens will have worked out how to transmit radio waves. We've been "radio loud" for nearly 120 years (although, with the advent of digital, our easily detectable analog signal will soon go silent) -- so should any eavesdropping aliens be within 120 light-years from Earth, they may have detected us.
But that's just accidental radio leakage -- what if we could turn our radio antennae to the stars and "listen" for ET's deliberate attempt to send a radio signal? Since the 1960's SETI programs have hunted for alien radio signals, but only recently, with the help of NASA's Kepler space telescope, have we been able to carry out directed searches on star systems that are known to contain exoplanets that could play host to an alien civilization. Although this directed SETI hasn't turned up a signal yet, there's potentially millions more "habitable" worlds out there -- we've only just begun.Slide 3 of 27
Running InterferenceSlide 4 of 27
There have been a few false alarms when listening out for a SETI signal. As we're looking for a specific, narrow-band radio signal (something that could only be generated by a form of technology), terrestrial interference can show up in SETI searches. Fortunately, astronomers are a savvy bunch and usually know the difference between aliens and Aunt Sally gossiping on her cellphone.Slide 5 of 27
Alien Footprints ... on the Moon?Slide 6 of 27
Alien Footprints ... on the Moon?
This is true -- though mainstream SETI searches focus on looking for suspect radio signals in deep space, it's worth keeping in mind that the moon is a pretty good rest-stop for any visiting aliens to the Earth-moon system. Looking for the equivalent of alien footprints on the lunar surface isn't so silly when considering NASA's Lunar Reconnaissance Orbiter -- that's currently in moon orbit -- can pick out Neil Armstrong's bootprints from 1969.Slide 7 of 27
ET LitterbugsSlide 8 of 27