ABSTRACT
The role of particles in communication has a lot to do with the directionality of information exchange. The development of human and technical communication systems is strongly related to the directionality of information exchange, too. A few examples can illustrate this fact: Oral and written letters have, in general, a sender and one individual or a small group of receivers. The spoken or hand-written message is the typical case for unidirectional communication. Talks and the exchange of letters can be understood as bidirectional communication.
