OK, I just finished watching Hollow Man. (Let’s save the remarks about my bad choices in what video to rent later.) Apperantly he had a problem with bright light because his eyelids were invisible, but wouldn’t this be the least of his vision problems?
Ok, his eyelids are invisible, but what about his irises? They wouldn’t be able to cut down on the amount of light his eyes are receiving, so it would be like having your eyes permenantly dialated. Not only that, but would his cornea even be able to focus light on his retina?
It seems to me that we would be effectively blind, anything in normal light would be a big bright blue. Any thoughts?
Good point! Yes, his retinas would be invisible too. It looks like anything in his body takes on the “invisible” property. At one point in the movie he vomits and his vomit is invisible.
On a visible person, do eyelids do anything for bright lights anyway? Obviously you can close your eyes entirely, but do most people do that as a reflex? I think my reflexive action would be to turn my head.
If he’s invisible he must be transparent, too. So that means that any light that hits his head, from any angle, makes it to his retinas. So his retinas are constantly being flooded with unfocused light coming from every direction. Under those circumstances I think it would be impossible for him to see anything at all.
A completely invisible person would be blind, but mostly because their retinas are not absorbing any light at all, so they don’t react at all to light.
Of course, they’d be bathed in light from all directions too, but the subjective experience would be total darkness, not overwhelming brightness.
Nahh, the cloaking device is a energy field that bends light around the ship. I’m guessing that its a one way phenomena, kinda like a two way mirror. Just like the predator suit.
BTW, the light-bending thing isn’t just restricted to Star Trek spacecraft. In H.G. Wells’ Invisible Man, he is not transparent, light simply refracts around him.
Of course, since light refracts around him, there’s no way his eyes could collect any of it, so he’d be blind there too. Same would go for the star trek ships.
When I was a kid, I always assumed that cloaked ships were just invisible to sensors (like space stealth) because you always saw them cloak and decloak on the Enterprise’s viewscreen which was linked to the sensors. Then they put windows on the ship in the Next Generation and you could actually see the ships decloak. Oh well.
Don’t forget about Star Trek IV, when they parked a Klingon Bird of Prey in the middle of a park. Wasn’t there a problmem with joggers running into it?
It all depends on the precise form of invisibility, I think–the common forms under discussion seem to be transparency and light bending. A third form might be “sample and retransmit”, which is probably easiest on the vision problem.
Transparency–You’re blind. Deal with it. Your retinas collect no light; if they did it would be a wash of unfocussed light (the lenses of your eyes don’t work either, or they’d be visible as distortions in the air).
Light bending–You can’t see visible light, or any other band that you’re making yourself invisible in. If you have sensors for other bands, then you should be able to get some kind of picture of the outside world from them. Of course, your enemies might have such sensors, too…
Sample and retransmit, which is how I’ve always thought of the Predator’s outfit, uses arrays of sensors and light sources to scan and reproduce incident light on the opposite side of the object. A simpler version would just alter the colors of the suit/hull to match whatever’s behind it without producing any light. There’s no reason you couldn’t rig this with a visor that provided a clear view of the outside world. Your whole suit is a camera, as well as a display screen–you could even have corners of the display showing what’s behind you. This is probably closest to a real-world application; we might see primitive versions of this in a few years.
Don’t forget magical, like Harry Potter’s invisibility cloak.
Actually, Balance, I think that sample and retransmit may be how ST cloaking devices work as well. I don’t think they’ve ever been entirely adequately explained. The ST Encyclopedia basically says they’re “an energy screen used to make something invisible.”
One thing to note is that a cloaked object, except in STIV, causes refractive distortions around itself. No idea why though.
I consider magical invisibity as a broader type, including as subsets all the categories previously mentioned, as well as psychic invisibility (magically convincing your target that you’re not there). Harry Potter’s cloak would be a light-bend with sensors (limited clairavoyance) device, for example.
I would also classify the ST cloaking devices as light-benders. Note that the “ripple” effect only occurs at the edges of the object as it’s moving. I would expect the ripple to be continuous throughout the cloaked area when a sample-and-retransmit cloak is in motion, due to propagation delays within the equipment. Of course, there’s no reason for any of them to ripple when they’re stationary.
