[Eric A. Taylor (OP)]

To become invisible you need to have light move around you then continue to the eye of an observer or have the light photons pass through you without interacting with the matter making up your body. If the photons are going around you, you won't have any entering your eye. If the photon go through your body (including your eyes) they will not interact with your retina. You may avoid this problem but you need to allow the photons to interact with your entire eye (lens, vitrines fluid and retina) and if you do that your eyes will be visible to others, and that would give you away.

Am I off base...Sorry George, but I think you messed up on this one....good book though.

This brings up another issue. All my life the backs of my eye have faced the inside of my head. If light enters the back of the eye and shines on the wrong side of the retina, what would one see?

[Madidus_Scientia]

Indeed, although if you had that kind of technology you could probably develop something so that you could see as well, ie via infrared, ultravoilet, or even echolocation or something.

All my life the backs of my eye have faced the inside of my head. If light enters the back of the eye and shines on the wrong side of the retina, what would one see?

Actually, our retinas already are backwards. The nerve fibres that go from the retina to the brain actually pass infront of the light detecting cells! How's that for intelligent design. A bit like draping all the cables for your tv over the screen. Anyway, the cells wouldn't know which direction the light came from.

[imatfaal]

Am I off base...Sorry George, but I think you messed up on this one....good book though.

who is George?

The cells of the retina would only need to be non-invisible to the extent that they must absorb some light.  How much light does the retina absorb in normal circumstances?  On dark nights we can tell that cats and dogs (who have better nightsight than humans) reflect a fair portion of light straight back out again. On the other hand you need flash photography to get any refelction out in day light.  I doubt it could be answered and I am sure it is impossible; but I guess that the light absorbed by retinal cells would not be enough to render them visible in the invisible man. 

Okay - what about his sweat? When does that become visible?

Matthew

[Bored chemist]

Off topic but whenever people are fighting invisible monsters in TV shows, how come the monsters don't show up when they get covered in dust during the fight?

[Geezer]

Am I off base...Sorry George, but I think you messed up on this one....good book though.

who is George?

That could be Herbert George Wells.

I wonder if he would have sold so many books if he had gone by Herbie?

[imatfaal]

He was known as Bertie - and I am not sure that would have gone down well either

[Eric A. Taylor (OP)]

Am I off base...Sorry George, but I think you messed up on this one....good book though.

who is George?

The great English Sci-Fi writer Herbert George Welles Auther of The Invisible Man (among other great works) I had a bet with a friend that someone would ask "George who?" (I won)

[Eric A. Taylor (OP)]

Off topic but whenever people are fighting invisible monsters in TV shows, how come the monsters don't show up when they get covered in dust during the fight?

In the film Forbidden Planet the Id monster was visible when trapped in the energy fence. The FX in that film were hand painted by they way. Not a Leslie Nelson film role you'd expect if you grew up in the "Airplane" generation.

[Eric A. Taylor (OP)]

Am I off base...Sorry George, but I think you messed up on this one....good book though.

who is George?

That could be Herbert George Wells.

I wonder if he would have sold so many books if he had gone by Herbie?

I always thought "H.G." was very proper for a Victorian English writer.

[imatfaal]

That's a very strange bet - the man's name was Herbert... 
"if I get an author attribution wrong I bet someone will notice"

[Eric A. Taylor (OP)]

His first name Herbert, but he went by his middle name.

[Travelguy1234]

We depend on the shape of our eye to bend and focus light into the darkness within our eye in order to see.

If the shape of a lens or eye could no longer bend or focus light and instead allowed light to pass through normally, it would distort or blur our vision.

We depend on our pupils to open and close to regulate the amount of light into our eye. If too much is allowed in, we would be blinded like stepping out of a dark room into a sunny day. When the inside of an eye is not dark it would not be able to differentiate the light coming in vs the light already there. Like trying to use a flashlight in the day vs at night. Eventually the receptors would stop functioning like if you stare at the sun for too long.

If someone was invisible, their pupils would constantly be trying to close and their receptors would be overloaded with light that could not be focused on. This person would only be able to survive in the dark or after the eyes stopped functioning or were removed.

[alysdexia]

A fòtomultiplier should solve that.

[Colin2B]

A fòtomultiplier should solve that.

But could you make an invisible photomultiplier?  []

[alysdexia]

A fòtomultiplier should solve that.

But could you make an invisible photomultiplier?  []

https://en.wikipedia.org/wiki/Quantum_dot + https://en.wikipedia.org/wiki/Superatom

[Colin2B]

Interesting idea, no secondary radiation.