Total immersion in an alternate reality is as old as the human race. Quite possibly they are even older than that. Dream realities, fantasies, campsite stories, the world of a good book. All stem from the desire to experience an alternative life, a different lifestyle, to be something different, or to escape what you are.

Total immersion in virtual reality itself, is also older than most bystanders would believe. From the original sensorium, created in 1962, by Dr. Morton Heilig, to the Sword of Damocles

In 1962, Heilig presented the multi-sensorial Sensorama which combined film, audio effects, vibrations, air movements, and scents. The Sensorama's technology may have been primitive, but in concept, it draws peer to peer with the most powerful modern systems.

Heilig believed that by expanding cinema to involve not only sight and sound, but also taste, touch, and smell, the traditional fourth wall of film and theatre would dissolve, transporting the audience into a habitable, virtual world.

Professor Ivan Sutherland's display "Sword of Damocles", built in 1968, was the first, crude demonstration of a system that might one day make virtual, indistinguishable from "real".

It consisted of a headband with a pair of small CRTs attached to the end of a large instrumented mechanical arm through which head position and orientation were determined. Hand position was sensed via a hand-held grip suspended at the end of three fishing lines whose lengths were determined by the number of rotations sensed on each of the reels.

It was, in short, the first Binocular Omni-Orientation Monitor, or BOOM display, and is generally regarded as the first VR hardware in existence, despite the prior existence of the sensorium.

The Elements of the Ultimate Interface

To begin with, VR worlds used two senses only. They were audio and visual, sight and sound. The ears and eyes being the easiest senses to swiftly replicate, and all we require for storytelling and simple interaction.

As time progressed, various types of of haptic and tactile interfaces became available. Haptic devices adding pressure whilst tactile devices added texture. Neither aspect of the sense of touch has yet to become as advanced as sight and sound in the virtual, but progress is being made at a steady rate.

In comparison, sound has been simulated thanks to techniques like binaural sound, almost as closely as it occurs naturally; the only remaining difference being in restoring a damaged sense of hearing to full fidelity.

Sight lags a little behind sound, and we still lack displays that can project the same arc minute density as the human eye can perceive. However, stereoscopic displays can deliver images as the brain expects, and the quality is again improving swiftly.

However, the problem comes when we reach the next two senses, olfaction and gustation or smell and taste. Neither has been simulated particularly well to date, with smell receiving the most attention, and taste, only as yet one device.

There are other senses to consider, of course. Proprioception is a mix of balance and intuition, coupled with other internal senses forms a greater whole: the sense of the relative position of neighbouring parts of the body.

We are unlikely to master proprioception until we have brain-machine interfaces supplying virtual bodies, which will not be for some time yet. However, with the other senses conquered, we will have most of the ultimate interface, a VR interface that makes use of full of five senses, feeding back to the brain as well as the natural body might, and immersing us in the sensorium of the virtual world. As the late Morton Heilig put it, "experience theatre".