Here's what I'm wondering:
If you're in a dark room with a window, your eyes adjust gradually to utilize whatever light is available. But if you're deep underground, far distant and cut off from any light source (I suppose there must still be a few photons bouncing around)-if it's completely dark, do your eyes adjust? Maybe it's a question of degree, but don't you need something to adjust to?
I believe this is correct. You could probably simulate the effect by standing in a walk in closet with the door shut and the floor toweled.
Here's an experience I had, that wasn't underground, but may be of interest (especially if you are cityborn).
I was on a ship in the Mediterranean at night. The captain announced that we were now out of sight of all land and other ships. There was no moon that night. He turned off all the ships lights, plunging us into utter darkness. After a minute or so, when my eyes had adjusted, I was amazed by the amount of light the stars alone produced. Everything was bathed in starlight, even producing highlights and shadow (and, of course, looking up I saw a sky filled with stars, probably more than I had ever seen before or since). I wish I had had a book with me, because I would have sworn I could read by it. (The reflection of light off of water is greater than on land, isn't it?)
Please excuse this if it is too far off to be of interest.
From my experience with complete darkness, my eyes don´t adjust to it. If there is no light source at all, I don´t see a thing. I think that the same is true for all humans (and most higher animals as well). Creatures adjusted to utter darkness have developed other ways to percieve their surroundings - a bats sonar comes to mind.
Stefan
I concur, I've been spelunking (with "professional" guides, mostly in upstate NY) at least a dozen times, if you somehow lose your light, your sunk, you see nothing. It's mandatory to have 3 light sources. People have been known to find their way out of cave systems by the flint in a bic lighter...truly awful, but not as awful as never finding your way out... ;)
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When I was young my boy scout troop took a tour of some old mine shafts in the Black Hills. After we walked down about half a mile we were cut off from all out side light sources and when we got their our guide had all of us turn off our lights. Unlike being out on a overcast moonless night or inside a house with the lights out there isn't any stray light sources for your eyes to ajust to, it was completly black. The strange thing is after about 15 minutes your eyes start fireing off random signals to your brain giving you the illusion that you are seeing sparkles or fireflys in your field of vision.
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-if it's completely dark, do your eyes adjust? Maybe it's a question of degree, but don't you need something to adjust to?
I've been on cave tours at Mammoth Caves National Park in Kentucky probably about a dozen times. One of tour guides' favorite tactics is to take a group down, then turn the lights off (they have electric lights throughout) to show you how dark it is below.
It is frigging dark.
Since there are no light sources whatsoever down there, i can't imagine your eyes would adjust. It's neat, and creepy, how dark it is.
-Skeld
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In a deep tunnel system, there isn't any light for your eyes to adjust to. I've been down deep in a mine, and with the lights off, you can't see anything; you could put your hand an inch from your face and not see it, and it doesn't adjust as time goes on.
It's terrifying that, back in the old days, when miners used to lose their lighting for any reason, they would have to sit down there alone for almost an hour in perfect darkness waiting for someone to come retrieve them. I wouldn't want to be in their shoes, I can tell you that.
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Here's an experience I had, that wasn't underground, but may be of interest (especially if you are cityborn).
I was on a ship in the Mediterranean at night. The captain announced that we were now out of sight of all land and other ships. There was no moon that night. He turned off all the ships lights, plunging us into utter darkness. After a minute or so, when my eyes had adjusted, I was amazed by the amount of light the stars alone produced. Everything was bathed in starlight, even producing highlights and shadow (and, of course, looking up I saw a sky filled with stars, probably more than I had ever seen before or since). I wish I had had a book with me, because I would have sworn I could read by it. (The reflection of light off of water is greater than on land, isn't it?)
Please excuse this if it is too far off to be of interest.
I had the same experience in the desert in Texas (near Big Bend). I was blown away by the sheer volume of stars and how bright (relatively speaking) they were. I really dug the eerie light and shadowplay on the cacti and rocks.
But, yeah, underground? No bueno. You ain't seeing anything. I've been to the Sonora Caverns and the Carlsbad Caverns, and without light, no way.
Thanks for the feedback, gents! Whenever I watch the Blue Planet episode about the creatures of the deep ocean, I feel sorry for them (the creatures). I can't imagine animals living their entire lives in that dark world, with eyes adapted to pick up the tiny amounts of light that filter down, and then a submersible goes down there blazing light. It must be searing agony.
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Thanks for the feedback, gents! Whenever I watch the Blue Planet episode about the creatures of the deep ocean, I feel sorry for them (the creatures). I can't imagine animals living their entire lives in that dark world, with eyes adapted to pick up the tiny amounts of light that filter down, and then a submersible goes down there blazing light. It must be searing agony.
Most of the deep sea animals, especaily the ones living at the bottom, are blind so you could set up a 10,000 watt arc lamp next to them and they wouldn't see it. The ones that can see their eyes are attuned to blue light waves and miss most of the light given off by camera lighting.
Now everybody take their experiences with being in the dark, and put yourself in your character's shoes.
In the Darklands.
Somewhere in that darkness, something exhales with fetid breath, and the senses you have remaining pick up the scent of humid, acidic spit, the feel of rough stone underfoot, and the sound of something moving towards you.
Pray for darkvision, but just outside of that ability's limit is still utter darkness.
RPG Superstar 2010 Top 16
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They've gotta have some light down there, Lilith. Othrewise, how would the drow be able to read anything? Or, for that matter, color-coordinate.
I can just see it now: centuries ago, the first surface dwellers showed up with these novelty light sources, and the drow suddenly realized that they were wearing pink and light teal equipment. It must have been mortifying.
No wonder the drow are so evil.
Luminescent lichen is your friend.
Ok So I have spent may years Spelunking in some great depths and have been a Certified Cave Rescue Technician and I can tell you all from experience that the statement about there not being any light is totally false. Everything gives off some form of light it is just a matter of the type of light. Our eyes have the tools required to, in some form, allow us to 'see; many types of light with time.
To give you all some perspective; when I was heavily Spelunking I would spend no less then three days at a depth of 1-3 miles below the surface of the earth. The standard rule I have heard and lived by is: However long it takes your eyes to adjust from a lighted room to moonless night darkness you need to add 8 hours for a depth of a mile down. So if you go from a well lit house to a moonless night and it takes you 25 minutes to adjust you need to get ready for total darkness for 8+ hours to the adjustment time.
Now before anyone gets weird on me let me say this. It will not be the same type of vision we as above ground dwellers are used to. It will be more of a grey scale with general shapes defined but it will be enough. This of course is dependant of geology and what life is down at depth. I have SEEN some extremely beautiful sights at depths of 3 miles where the light being issued forth from the rocks and the life forms was so colorful it brought tears of wonderment to my eyes.
However; and this is the most important part of the process; the return to the surface is more time consuming and more dangerous...That's right Dangerous. The longer you spend in "relative darkness' the longer it takes your eyes to properly adjust to light. The rule we used was once you started getting the slightest hint of light you should give yourself 2 hours of adjustment before going any further and when you move it should only be 5-15 feet depending on light levels per feet. I have seen people go blind from not following this rule.
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captramses wrote: *stuff*
Is this just your experience or is there any documented evidence. I only ask this because I have never heard of any geologist or mineralogist saying that rocks give off light. Maybe in natural caves with colonies of glow worms or some kind of bio-luminescent fungus you might get some light. but most cave systems that I know of don't have anything like that at all.
Ok ...
I know a spelunker who also told me there are bioluminescent light sources down there (EDIT: in/near water), but then he also said you don't find them everywhere, and that you can't really see anything but blobs. Something about cones and rods... and you can't see anything if you look right at it. (EDIT: Now that I think about it he did smoke an awful lot of marijuana.)
The 8 hour adjust I don't know... but he slept with the lights off and when he woke up he used to spend some time in the dark.
But it's dangerous to move around in the dark and any spelunker with a wit of intelligence won't do it for long.
As far as going blind... well... that's pretty over the top and sounds like my mom telling me carrots grow hair on my teeth because these dudes sleep all night with the lights off and their eyes closed and then fire up their Xenon lamps and nobody screams out and goes blind... and that's some bright shit.
Someone is pulling our little legs.
Apparently there are caves in New Zealand with all kinds of freaky glowing stuff.
<reaches out of the darkness with a zippo aimed at yer eyes....>
SNARK!!!! You're now BLIND!!! SNARK!!!
Apparently there are caves in New Zealand with all kinds of freaky glowing stuff.
It's the whacky-weed the locals are smokin, I tells ya!!!
But watch out for them Grue!
And those mushrooms are all aboveground Ubermench. They're still cool though.
Plus they need AAA batteries.
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Check itBut does it grow in a dry cave?Man, there's water around every corner once you get down into the deep. Not always enough to drink, but you know those pointy things on the ceiling? Made by dripping water.
Dry caves have water too but they have been lifted by geologic forces and the rock formations no longer grow (a dead cave). Other cave systems formed by lava flows have water in them but have none of the regular rock formations found in water or tectonic formed cave systems.
<-----mistook for a spelunker or geologist.
I trade only on hearsay and talk only in sweeping generalism. Don't parse with me brother.
;p
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Dry caves have water too ...
snicker...
All in fun.
Off to work for me. HAHahHAHHahAHhahHAHHA!
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I'm bored today. And this has really piqued my curiosity because I have never heard this before and it's completely outside my experience. Turns out, the National Speleological Society's main office is here in Huntsville, Alabama. So I called them.
Again: I'm bored and curious. I asked them if your eyes would adjust. First they laughed. Then they told me that, no, your eyes don't adjust. Otherwise, cave fishes' eyes would have adjusted. Instead, they went blind because their eyes are useless from the lack of light.
Given this new information, I call shenanigans.
-Skeld
Shenanigans? It sounded to me like all the testimony agreed. Nice info, actually--thanks for sharing.
Shenanigans? It sounded to me like all the testimony agreed. Nice info, actually--thanks for sharing.I think captramses was having his eyes play tricks on him.
Or doing some really cool shrooms...
I'm a geologist. Yes, some minerals give off light under proper conditions. No, "everything" doesn't "give off some kind of light." The best you'll get is an emission of heat from warmer objects/patches, which nothing short of IR goggles will let you see.
I used to study computational theories of vision in college, and as a lark, once spent 45 minutes in a sensory deprivation room. The room had zero sound reflectance (if you were to stand back to back with some in the room, you could not hear anything they said) and was 100% lightless.
What happens is, as your eyes try to adjust to the low- or no light conditions, the rods and cones in your eyes continue to fire. This creates a mild visual hallucination (basically, like colored white noise on a tv screen, but much subtler). After a while, the receptors completely reset, and you see nothing. At this point, I stopped mentally taking notes, because the sounds of my blood flowing through my head beat were becoming very unnerving.
Upon returning to a lighted area, colors will be quite skewed. Initially, incandescent sources of light will appear very orange, greens will be more green, etc. This lasts for a couple of minutes, until the cones that are sensitive to higher band spectrum being to tire and desensitize.
In a low-light area, you would see more grays.
Fun fact, most mammals do see color, just muted shades of color, as they have more rods than cones in their eyes. This gives them better lowlight and night vision, as well as better detection of motion, at the expense of accuracy.
If you are interested in the science behind vision, you can't go wrong reading some of the works by the late Dr. David Maar (wikipedia
Shenanigans? It sounded to me like all the testimony agreed. Nice info, actually--thanks for sharing.I think captramses was having his eyes play tricks on him.
Maybe he was stoking up with my buddy down there in Virginia.
... Although to my friend's credit it sounds now like he was talking pretty straight about it.
Given this new information, I call shenanigans.
-Skeld
And thanks for the scoop. And we're glad to have livened up your day!
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What happens is, as your eyes try to adjust to the low- or no light conditions, the rods and cones in your eyes continue to fire. This creates a mild visual hallucination (basically, like colored white noise on a tv screen, but much subtler).
Sensor noise. Noise equivalent irradiance (NEI). There are a couple of other names for it too.
-Skeld
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But if you're deep underground, far distant and cut off from any light source (I suppose there must still be a few photons bouncing around)-if it's completely dark, do your eyes adjust?
Been in several caves. When they douse the lights, it is dark.
It is a darkness you have NEVER experienced before. There is NO light whatsoever. You do not see, or even think you see, silhouettes, shapes or anything. Darkness fills every corner. You can literally hold your hand to your face and you cannot see ANYTHING about it at all. Some people even have a bout of vertigo because they've lost all reference to up and down and their mind takes off with it.
In the Infantry we've always taught it takes around 9 minutes for the rods and cones to adjust to the change in light (don't ask me to quote a reference because I cannot - just one of those pseudo-science things that seems to get passed on.) I can say with some certainty that, while I have never measured it, this is not too far from accurate regarding my own physiology.
When I was in one cave we kept the lights off a good while. My eyes NEVER adjusted. I have never been in a cave for much longer than a couple of hours so I cannot confirm or deny the 8hr + 25 min presented before.