Puzzling things about the Invisible Man

Some of you may have read H. G. Wells’s novel The Invisible Man. There have been several films based on it that I have not seen but as a young boy, I was fascinated by a TV show that was based on the same idea but is set in modern times and is otherwise nothing like the book. In this show, as in the book, a scientific experiment gone wrong makes a man completely invisible, so he goes around wearing clothes, gloves, sunglasses, hat and with his face fully bandaged in order to keep his invisibility secret and make his presence visible and not freak people out.

In the TV series he becomes a secret agent for the British government and has all kinds adventures each week that required him (and this was always the highlight of each episode) to remove the bandages and clothes for some reason and move about invisibly, startling passers by who see any stuff he is carrying floating in the air and seeing a car that he drives (often inexplicably a convertible with the top down) going along the roads with no one at the wheel. With the advent of driverless cars, people now would be less perturbed.

But there are many problems with the concept that Wells necessarily had to skirt over. One is that if the man is invisible because his refractive index for light is exactly one so that light passes straight through, that would also mean that the lenses of his eyes could not cause incoming light to focus on his retina and he would be effectively blind.

This cartoon points out another problem that I don’t recall the TV series addressing and that is what happens when he eats and drinks? At what point does it become invisible too?


  1. OverlappingMagisteria says

    If I remember correctly, the book did address the issue of food. Food would not become invisible and the invisible man would not eat anything for a day or so before he planned to disrobe and be fully invisible. Otherwise you would see floating bits making their way through his digestive system

  2. suttkus says

    Actually, the book made mention of the cat that Griffith experimented on first retained it’s retinas as just visible, presumably to get around the blindness issue. It wouldn’t work, though. Without the iris to control light, the retina would rapidly be burned blind. Now, try thinking about how the invisible lens would work until your brain explodes!

    There are all kinds of problems with this, really. When does “the body” begin and end? Hair and fingernails are dead tissue, they shouldn’t transform because you swallowed a chemical. But then, you could say that about the epidermis as well!

    It would be easier (in the science fictional sense!) to achieve the effect of invisibility by moving the character sideways a little in a fourth spatial dimension, letting him control how he interacts with with the three we normally interact with. This would allow him to wear clothes normally as well, and turn anything he decided to pick up invisible by pulling it sideways with him. He should also be able to walk through walls. Talk about a reign of terror! (For anyone who hasn’t actually read the book, the Invisible Man is NOT the hero, he’s a monster, it’s a horror story. A lot of adaptations skip that bit and turn him into a superhero.)

  3. says

    There was a Chevy Chase movie where he turned invisible and they did show him eating and the food going in, but if I recall correctly it didn’t take hours to become invisible.

    The blindness thing has been annoying me for years when it comes to invisibility. How can an invisible human not be blind? (I’m also annoyed by vampires not showing up in mirrors. If we can see them, they’ll have a reflection! That’s how light works!)

  4. Dauphni says

    The vampires not showing up in mirrors thing is pretty early explained, actually. It’s because when a lot of the classic vampire stories were written, most mirrors were backed with silver to make them reflective. Silver is of course notoriously harmful to vampires, so much so that it will eat the very light that bounces off them. That also explains why they don’t show up in photographs, as the photographic emulsion contains silver. Of course that should leave the image of the vampire as an indistinct blob, not clear see-through, but that doesn’t look as compelling on tv. It also means that vampires should show up on digital cameras and modern aluminium mirrors!

  5. Andrew Dalke says

    suttkus: if a slight movement into another dimension would let someone walk through a wall, then what would prevent that person from sinking into the ground? That was a problem with the so-called “Philadelphia Experiment”, where a supposed invisibility device caused some of the sailors to become embedded in the ship’s structure.

    Another SF handwaving explanation these days might be “metamaterial”.

  6. Dr Sarah says

    Yeah, I was also thinking of the Chevy Chase film. In the book it’s based on, ‘Memoirs of an Invisible Man’, it is specified that once the food has been digested it becomes invisible, so the invisible man has to eat things that are very quickly and easily digested to avoid giving away his whereabouts; if he eats a nut or seed, for example, it can remain visible inside him for days.

  7. derek lactin says

    I remember an episode of Star Trek TNG, in which the inhabitants of a planet were invisible because they were offset in time by a couple of milliseconds. Data announced this as if it were totally unremarkable. That’s all I remember of the episode.

  8. fozollie says

    I recently re-read The Invisible Man and was surprised at how dark it was. The protagonist is miserable, cut off from society he becomes increasingly prone to fits of sudden rage, violence and frustration -- it is quite psychologically intense and has a very different tone to what I expect the TV series has (having not seen it, but it sounds like a fun adventure series).

  9. says

    The obvious way to allow your character to see would be to render them invisible only to wavelengths that an unaided human can see, and them have them see in either infrared or ultraviolet light. That’s how the protagonist did it in the Sc-Fi Channel series “The Invisible Man”. In fact, at times he would use his invisibility power specifically FOR the infrared vision aspects.

  10. suttkus says

    Dalke: It’s hard to understand how adding the ability to move through a fourth spatial dimension works, but as a metaphor, imagine encountering a two dimensional world. (I am assured that the math works out the same way.)

    So, you’re walking along, and suddenly you realize that you can see before you, stretched out about chest height, a series of two dimensional beings. They all occupy a single plane that, to them, seems to be the entirety of the universe, despite being only one small plane in the larger three dimensional universe that we know. Their bodies are shapes like squares, or circles, with flat internal organs (don’t think TOO hard about how that would work). They move around in their singular plane. Being two dimensional, they don’t have mass, and are unaffected by gravity from our planet, which they cannot perceive because it is below their plane.

    If you reach a finger into the plane, they will perceive only the cross-section of your finger. Put all five fingers in, and they’ll perceive five roughly circular shapes. Push further and your hand goes in, they perceive the five separate shapes somehow fusing into one! Push further and your arm starts to go in, and if your arm is like mine, they’ll start perceiving that the circle of your arm is surrounded by weird dots that appear, at random and then merge into the body of the circle, or vice versa. That would be the arm hairs.

    Of course, you can perceive the entire interior of the shape-creatures in this plane. You can EVEN REACH INSIDE THEM and poke their internal organs, something that their two-dimensional brains would have trouble conceiving. They can’t hide behind barriers, because you can just reach inside those as well! You are a monster who can ignore walls!

    A being with four spatial dimensions would be a lot like that compared to you and me. He wouldn’t “fall” through the earth, but he’d presumably be standing on some existing four-dimensional construct we can’t perceive, or can perceive only a part of. He would be capable of ignoring the surface of the earth, but that wouldn’t constitute falling. (Presuming that the Earth is a three dimensional world. It could be a limited perception of a four-dimensional thing itself, of course.)

  11. johnhodges says

    The original novel points out many practical difficulties that an invisible man would face. Walking significant distances in bare feet over less-than-ideal ground, carrying anything (keys, money, weapons), eating in public places (have to remove face covering to eat), mud or dirt adhering to skin, dogs alerting to the sound or scent of your passage, wet weather, cold weather, catching the common cold so you sneeze at awkward times… We politely ignore blindness and basic impossibility for the sake of the story.

  12. brucegee1962 says

    The novel Memoirs of an Invisible Man probably goes the farthest in exploring all the implications. That guy spends most of the book on the run from Sinister Government Agents who want to experiment on him or something.

    Of course, while reading the book, I had to put some thought into what I’d do if put in a similar situation. I think the best option would be to apply for a job at the CIA. “I’ll learn Russian, I’ll go on spying missions for you, I’ll be your top agent — but good luck getting any cooperation from me if you try to double cross me. All I want in exchange is a cushy luxury apartment, a juicy salary, and unlimited internet access when I’m not on a mission.”

  13. Onamission5 says

    @suttkus #2: Seems one would have the same problems with microbes; they aren’t fully part of the body, although they can assist in or detract from function, and we’re covered with them inside and out. Would the trillions of constantly reproducing/replicating microbes we carry around with us also be invisible due to having possibly come into contact with the ‘invisibility chemicals’ or would an invisible person retain a sort of vague and blurry form because invisibility isn’t transferrable from the initial microbes to its replications?

  14. Jenora Feuer says

    @Dr. Sarah #6:
    Of course, that gets used against him. The government agents after him already know about how the digestion works (he wasn’t the only person affected; an entire building was turned invisible) and once they find reports of missing food that matches the sort of food an invisible person would want to eat to stay invisible as long as possible, they lay a trap with the perfect food being set out somewhere he can get at them, but laced with tranquilizers.

    @brucegee1962 #12:
    And that approach is pretty much what the main character did in the novel of Jumper, though in his case it was teleportation rather than invisibility. Set himself up as an agent because he realized that eventually a lot of people were likely to be after him and it was best to find a patron.

  15. says


    I remember reading a science fiction story (by William Tenn?) of some astronauts who ran into fourth dimensional creatures. They could just pop up anywhere. They would appear as a small sphere and then expand.

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