Who is looking for etraterrestrial signals? What can we expect to learn form messages from other civilizations? What informaion are we beaming to distant civilizations?
In the late 50s, the astronomer Frank Drake was one of the pioneers who actively looked for electromagnetric messages from extraterrestrial sources. The task wasn't easy; the electromagnetic spectrum is very vast, which means that a great number of signals can be carried simultaneously and withouth interference. Since it is not known what frequencies extraterrestrial civilizations, if any, would use to send electromagnetic signals to potential listeners, one would need to make some guesses as to the part of the electromagnetic spectrum the extraterrestrials are likely to use.
It is clear that we don't expect to receive a message in English! A far-away civilization will try to establish a contact by broadcasting information that other dwellers of this galaxy might understand. What can this informaion be? As we are well aware here on Earth, civilizations that rose through recorded history developed their own languages and means of communication. Something that is well known to a certain civilization might be completely foreign to another. Communicattions will start when the two sides understand they have something in common. What can civilizations thousands of light years apart can have? It is the laws of physics! We hold that such laws are universal, which means that they hold throughout the Universe. Thus, it is possible, or even likely, that another civilization, in its first effort to make contact, will send us some inofrmation about physics laws. For example, they could....
The Federal government used to support research aimed at listening
to signals from outer space. Funds were cut in the 80s because
Congress deemed this type of research of little value. Private donors
stepped in and the SETI Institute became a private research institute
devoted to the listening of signals coming from space.