In the novel 'The Invisible Man', H. G. Wells demonstrated with wit and logic that an invisible man acquires an almost unlimited amount of power. He is able to enter any place unnoticed and steal anything with impunity. Elusive, thanks to invisibility, he successfully fights a whole crowd of armed people.
Threatening to smite all those who are visible, the invisible man subjugated the population an entire town. Elusive and Invulnerable, The Invisible Man strikes down all their opponents despite their every precaution. The invisible man is thus able to issue to the terrified population of his home town an order.
"I am Invisible Man the First. To begin with, the rule will be easy. The first day there will be one execution for the sake of example―a man named Kemp. Death starts for him today. He may lock himself away, hide himself away, get guards about him, put on Armour if he likes―Death, the unseen Death, is coming."
At the outset, the invisible man triumphs. Only with the greatest of difficulty do the terrorized townsfolk rid themselves of their invisible foe who dreamed of becoming their all-powerful master.
Are the physical theses on which this science fiction novel is based right? Undoubtedly yes. In a transparent medium every transparent object becomes invisible when the difference between refractive indices is less than 0.05.
Ten years after H. G. Wells' 'The Invisible Man' was published, a German anatomist, Prof. W. Spalteholtz, put the writer's idea into practice―not on living organisms but in the preparation of dead specimens.
Such transparent preparations of organs and even whole animals may be seen today in museums. The transparent preparations method evolved by Prof. Spalteholtz in 1911 is briefly as follows. After treatment―bleaching and washing―the prepared specimen is soaked in methylsalicylate, a colorless liquid with a bug refractive index.
Specimens of rats and fish, or various human organs thus prepared, are placed in jars containing the same liquid. However, full transparency is not sought as this would cause the specimens to become absolutely invisible and consequently, useless for the anatomist. We could achieve full transparency if necessary though.
This is naturally far from Wells' dream of a live man so transparent as to be absolutely invisible. Firstly, because we must know how to treat living tissue with this transparency liquid without violating organic functions.
Secondly, because Prof. Spalteholtz's preparations are transparent but not invisible. They are invisible only while immersed in a liquid of corresponding refractivity. They will be invisible in air, only when their refractive index is the same as that of air, which is something we are still unable to achieve.
However, let us imagine for a moment that with time we shall be able to do this and consequently realize the British novelist's dream. H. G. Wells was so thorough, that one can't help believing him and his thesis that an invisible must indeed be the most powerful of all mortals. This is not at all so. There was one point that the author overlooked.
Can an invisible man see? Had Wells ever stopped to ask himself this question before he embarked on his novel, we would never have had the pleasure of reading his gripping narrative. This upsets the entire apple cart because the invisible man must be...blind.
Why couldn't the invisible man see? Because every part of his body, including his eyes, was rendered transparent, and possessed a refractive index identical to that of air. Let us now recall the eyes function. Its crystalline lens, vitreous humor, and other elements refract light so as to produce a retinal image of surrounding objects.
When the refractivity of the eye and that of air are equal, the sole cause of refraction is removed. Passing from one medium to another, of the same refractivity, light will not change its direction and, consequently, its rays will be unable to concentrate in one point.
Light will pass through the eye of an invisible man without hindrance; its rays will neither be refracted nor retarded―since there is no pigment. To induce a sensation in animals, rays of light must bring about some changes even of the most insignificant nature; or in other words, perform certain functions in the eye.
Consequently, at least part of the rays must be retarded. An absolute transparent eye will naturally be unable to check rays, otherwise it wouldn't be transparent. All creatures drawing upon transparency for protection have eyes that not completely transparent, provided they have eyes.
'Immediately below the surface', the well-known oceanographer Murray writes, 'most animals are transparent and colorless. When taken from the tow nets they are often distinguishable only by their black little eyes, their blood being devoid of hemoglobin and the entire body perfectly transparent―and consequently will fail to produce any mental image."
To Sum Up
An invisible man sees nothing. He will derive no benefit from all his advantages. This formidable claimant of power would have to grope in the darkness begging for alms which nobody will be able to give, as the applicant would be invisible. Instead of the most powerful of mortals we would have before us a helpless cripple doomed to a miserable existence.
In other words, if we desired the cap of invisibility, it would be futile for us to copy Wells. Even a successful result would be a sorry one.