PRESENCE:: the sense of believability of inaccessible worlds

With the development of new instruments as telecommunication, teleoperation, computer representation tools, human beings are commonly in situation to perceive and act on spaces that are more and more distant or different from our physical world. These new tools raise nowadays the question of Presence of these distant spaces with a growing intensity. This question crosses disciplines as different as computer arts or nanosciences. Through two experimental situations in each of these fields, (1) the playing of a musical virtual instrument and (2) the manipulation of nano-objects, the paper analyses the minimal conditions that the computer models and the human-computer interactions have to satisfy to trigger the sense of presence of distant inaccessible objects, whatever they are. After examining the evolution of instrumental tools, machines and concepts from real means to televirtual ones via the teleoperation and telecommunication chains and via experiments for the investigated fields, the paper shows that the primary condition able to generate ab initio the sense of presence, should be the instillation of a minimal physical coherence in the representation of distant worlds, and the introduction of the "evoked matter" concept as a central paradigm for the Presence issue. (C) 2004 Elsevier Ltd. All rights reserved.