The Problem of the Invisible Man

Many individuals have speculated that being invisible would provide a lifetime of entertainment and a perfect stealth with which to perform espionage upon others. However, there is one flaw to this entire ideal. Even if one were capable of rendering one's self invisible, one would succeed in crippling one's self equally well. If light is unaffected by a physical body, if no energy is transferred from the electromagnetic wave we know as light to the retina, no image can be seen. Thus, one would be absolutely blind. To understand this fully, one must understand a little physics.

Light is a moniker for a certain, narrow band of frequency in the electromagnetic spectrum. Light travels in packets known as photons. When a photon strikes an electron, it transfers a certain amount of energy dependent on the frequency (which is dependent on the energy) of the electromagnetic wave the packet is a part of to that electron, generally temporarily causing that electron to jump to a higher energy level and perhaps to a higher valence. When the affected electron is a part of a cone or a rod in the retina of the eye, the energy transfer is registered as color. The color depends on the amount of energy transferred and the size of the jump in valence. But, if something is invisible, it implies that light passes through the object without ANY interaction which would change the properties of the light. This means that NO energy can be transferred to any electrons from any photons, and thus, no valence levels are changed and no light is seen.

In Quake, when a player picked up the ring of shadows, they turned invisible, except for their eyes, which of course is why they continued to see.

It was insightful for Carmack to think of this. This greatly improves my opinion on Quakes physics engine...

While Inebriated Poet did a fine job of explaining the physical limitations of being invisible, he skipped some of the more simple, yet often over looked problems. These stem from certain advantages of being visible which are taken for granted by most.

Given that one has some how gained the ability to see, (through the logical method used in Quake, or some more fantastic solution) One would still presumably be invisible to themselves. This would most likely cause some difficulties with depth perception and balance. (Never having been invisible myself I can't swear to it.) Being invisible would also be somewhat dangerous as you would have only yourself to rely on to prevent collisions, from pedestrians, motorists, and what ever other sort of traffic may be present.

Faced with these challenges I would say that if one were to have the ability to become invisible, it would be best to have reliable control of ones visibility. I would also say that I watch too many sci-fi shows involving invisible men... but that's not the issue.

The sci-fi shows in question were, obviously, The Invisible man,as well as The X Files, Ghost in the Shell, and countless others.