Another part to this is the influence Paul Davies’ book, The Eerie Silence, and the search for Alien Intelligence. Not so much whether we are alone, or there are other beings out there in the vast universe, but more, how might Aliens’ find meaning in our broadcasts even if they were to intercept them.
Hofstadter examines whether meaning can be said to be inherent in a message, or whether meaning is always manufactured by the interaction of a mind or a mechanism with a message. He invites the reader to consider a thin plastic platter with a hole in the middle (we know this to be an old fashioned record containing music) is hurled into deep space. It has lost all context, music, record-player, etc. How much meaning does it carry? If an alien civilization were to encounter it, they would almost certainly be struck by its shape, and would probably be very interested in it. Thus immediately its shape, acting as a trigger, has given them some information: that it is an artifact, perhaps an information-bearing artifact.
We can imagine that if such a record had arrived on Earth in Bach's time (1600’s and 1700’s), no one would have known what to make of it, and very likely it would not have gotten deciphered. If we imagine for a minute that we are bathed by a sea of radio messages from other civilizations, messages which we do not yet know how to decipher – a deep problem is the question, "How will we recognize the fact that there is a message at all? How to identify a frame?"
In these examples of decipherment of out-of-context messages, we can separate out fairly clearly three levels of information: (1) the frame message; (2) the outer message; (3) the inner message. The one we are most familiar with is the inner message. It is, after all, the message which is supposed to be transmitted: the emotional experiences in music, the phenotype in genetics, the royalty and rites of ancient civilizations in tablets, etc. To understand the inner message is to have extracted the meaning intended by the sender. The frame message is the message "I am a message; decode me if you can!".
The three levels are very clear in the case of a message found in a bottle washed up on a beach. The first level, the frame message, is found when one picks up the bottle and sees that it is sealed, and contains a dry piece of paper. Even without seeing writing, one recognizes this type of artifact as an information-bearer. Next, one opens the bottle and examines the marks on the paper. Perhaps, they are in Japanese; this can be discovered without any of the inner message being understood. It merely comes from a recognition of the characters.
It is in the nature of outer messages that they are not conveyed in any explicit language. It is always the listener's burden to understand the outer message and the success of that lets him break through into the inside, at which point the ratio of triggers to explicit meanings shifts drastically towards the latter. This is a bit like recognizing in a sea of radio signals that a particular signal is a frame – a bottle carrying an inner message.