In two earlier posts I mentioned how some alien races may communicate via light instead of by sound (Music and
Alien Technology - 1. Biology/Physiology - Part II). This may not be so far-fetched. On Earth there are creatures that are capable of communication via light.
In the June 2009 issue of Scientific American is an interesting news article about the possible ability that some single-celled organisms communicate via electromagnetic radiation. Dr. Daniel Fels of the Swiss Tropical Institute in Basel ran a series of experiments involving paramecium. Paramecium populations will slow their growth rates when other near-by paramecium populations are detected. He found that when groups of paramecium were separated by glass that allowed UV to pass through, their growth rates slowed. But when groups of paramecium were separated by UV blocking glass, their growth rates increased.
...To Lightening Bugs...
... And Lightening Little Green Men?
Some in the SETI field feel that some alien civilizations may actually communicate by laser light rather than radio signals. For an alien race that communicates personally via light, it may be more natural for them to use light for space communication. Instead of a radio signal, our first contact from space may not be flashes of light.
Choi, Charles Q. "Electromagnetic Chatter." News Scan. Scientific American. June 2009. 32.
"Optical SETI - OSETI." Life in the Universe. 8 August 2001. 13 January 2008. <http://www.lifeinuniverse.org/noflash/OpticalSETI-07-01-03.html>