E.T., phone earth - and provide a translation.

If E.T. phones Earth, will we understand what he is saying? Many scientists involved in the Search for Extra Terrestrial Intelligence (SETI) project assume that, if they detect signals from intelligent aliens, it will be only a matter of time before the messages are decoded.

That assumption is overly optimistic, given what researchers know about the nature of communication and language, according to Neil Tennant of Ohio State University's Center for Cognitive Science. He maintains that the work of the best cryptographers and supercomputers probably will fail to translate the signals of extraterrestrials into messages humans can understand. "I think some of the SETI proponents are really exaggerating the possibilities of meaningful communication. The public may be misled about the prospects of receiving understandable messages from extraterrestrials."

One of the major problems with decoding alien signals is that Earth most likely will receive nothing but a series of electromagnetic "bleeps" from outer space. Modern philosophers and linguists believe that language is meaningful only when it can be observed and understood in the context in which it is spoken. it is necessary to see speakers in their natural environment, interacting with things around them.

For instance, most people believe they get more meaning out of a conversation when they...