Lately I have been exploring the idea of invisible, intangible interactive systems and how they would be experienced. So much of everyday interaction deals with sight and touch. We rely on visual and tactile feedback to manipulate and understand physical systems. How difficult is it to understand and know a system when these two components are removed leaving only sound? Everyone has had the experience of stumbling through a dark house at night to get a glass of water, but relied primarily on the sense of touch to get by. What happens when Newton’s 3rd law no longer guides us and the glass we grasp doesn’t press back on our hand? The closest experience I can think of is the theremin, although the underlying system is limited in potential complexity.

The first piece I have made to explore this concept features invisible wind chimes. When a person walks through the space occupied by the virtual chimes, they begin to ring. Should the actor stop to explore the source of the sound, he will uncover a fine-grained, predictable, knowable system. Using computer vision techniques to detect movement in a space, real, physical objects are able to interact with virtual, “physical” ones. Although not concrete, they are still physical because a physics simulation ensures the individual chimes still hang behave in ways we know and expect. They hang from the ceiling by strings, collide with each other (causing them to ring), swing and respond to gravity by eventually settling back to rest, and respond to touch by a soft body (muting any ringing).

Invisible Chimes is an intangible, interactive system that prompts us to consider how we acquire knowledge of complex systems from limited experiential data. The chimes, though installed in a space, cannot be seen, and while they can be touched, they cannot be felt. The only indication of their presence is the sound they make. Nevertheless, the system is still very much a “physical” one, in that the chimes are governed by the laws of physics. Although they can be appreciated by simply walking through them, further interaction reveals that the individual chimes can be separated, muted, and lifted, and that they behave in a predictable, understandable way. The inset video reveals the physical model the custom software uses to create the interactive system.