Why is light necessary for vision?
475464
Go into a closet and think about it.
438458
General thought about looking directly at very bright light is correct. The lens of our eyes can project a many fold brighter image on the retina. This can damage the rods and cones in your retina and can even cause permanent damage to your vision.
94315
To Improve Peoples Eye Vision
111323
I see the point in your question.  I think you are asking why  do we not see an aura of light, since light would still be passing around us.\n\nLight is an electromagnetic wave (OK, some might say rightly that this is debatable since it sometimes displays properties more accustomed to matter.  However, this dual nature does not imply that light is not an electromagnetic wave).\n\nThat said, one must understand that the e-m wave in itself is invisible.  It is the retina in our eyes which is sensitive to these rays.  Imagine this example.  Light a torch in a dark and clean room (no dust flying about!).  You would see the paper, but you won't see the light travelling from the torch to paper!  That is unless dust, or humidity, reflect this light and you would see a beam of light.  Similarly if you take a magnifying glass, you can see the image, but can you see the light coming out of that image? No.\n\nSo, though light would be passing around us, since nothing, except of course the Moon, satellites, and planets would be reflecting it, we cannot see it!
322359
Because light is just a wave. It doesn't have any mass. It's an electromagnetic wave, just like radio waves and x-rays.
551674
Short Answer: no need to develop pigments.  \n\nThe explanation: sunlight is harmful (ergo you use sunscreen) because of UV light, and pigments are produced by our skin cells to absorb the force brought on by UV rays, keeping your DNA from absorbing them.  If you're not exposed to sunlight, your skin doesn't need to produce and therefore doesn't produce much pigmentation, if any.  Same happens in animals.  If their permanent condition is as such, they eventually lose all ability to produce pigments simply because they can invest the energy on something that will give them the advantage to survive in their environment.  \n\nAs for blindness, you need light in order to see, and just like we can't see in total darkness, fish can't see in darkness either.  So, animals that live in absolutely dark environments don't need sight, and thus don't have it.  They'd rather spend the energy needed to develop sight (which is useless) in developing other sensory organs that will give them an advantage as hunter, to avoid being something else's lunch or both.\n\nMulti colouration in animals exists for many reasons, the two main ones are \n\n1- as disguise to fool prey (to eat) or to fool predators (to not be eaten)\n\n2- as an attractive feature for sexual selection, so that potential mates identify them clearly and select them for mating.  \n\nIn any case, competition to be the best hunter, the best hiding or the one that attracts more females or males drives selection and thus evolution.  \n\nRemember: if you get eaten, die of starvation or don't reproduce, you don't get to pass on your genes.  As such, any special traits you might have do not get passed on in the gene pool and those traits dissapear with your dead rotting self.  If more humans knew this, we'd be a little more appreciative of our uniqueness (read: selfish) and suicide rate would go way down.  \n\nThat's what evolution is all about, survive until you get laid and knock someone up or to get someone to knock you up.
666930
less light makes it to your eye
12543
From a physics/physiology standpoint, we have color because light waves come in different lengths and our eyes perceive a limited band of thoses lengths with differing responses by light sensors in the eyes.\n\nFrom an evolutionary standpoint, color vision (as opposed to black and white), gives us a great deal more information to process our environment.  For instance, a brightly colored bird might hardly be visible to an animal with only black and white vision, but we see it easily, even against a confusing background.  Color can help us see the difference between animal (browns) and plants (greens), healthy(a child covered in mud) and unhealthy (a child covered in blood), and other differences that are more easily recognized due to the greater information richness available.
1043069
B - the reason you can see an object is because light bounces off of it. if light bounced off of an object evenly, then you would have to be in a specific location to see it (think of a mirror reflecting a laser. you can't see the laser beam in the mirror, ideally, if you are shining it at an angle). if the light is reflected unevenly, then you can see it at pretty much any angle.
209308
if we need light to see, what does light use to see? How does light illuminate itself. The answer is that light is light already, you are the one who needs it to see. You cannot fathom the mystery of God but God is existence itself and it is impossible for such not to actually exist
1164989
The energy from the light is absorbed into the walls, etc.  If you could create a room that had everything in it 100% reflective, then the light would continue to exist.  But, you wouldn't know this, because you are not 100% reflective, and you would absorb the light.
318462
The sun shines for the same reason a fire radiate light.\nAnd we need the sun because without it it would be freezing cold outside. In fact the Earth and all the solar system wouldnt exist if the sun wasnt there because there wouldn't the gravitational field the sun provides to gather elements and form planets.
942592
The size of the eye is only important because larger eyes mean that more light can enter the eye.  That is one of several adaptations that nocturnal animals have to increase their vision at night.  To understand why this is important, you have to understand how vision works.  Basically, most animals have both rods and cones.  Cones are responsible for clear vision during the day, while rods are responsible for vision in low light and for peripheral vision.  Having large eyes is good, because it allows more light to pass into the eye, but that's not good enough to have clear vision at night.  Most of the light that passes into the eye does not hit a rod in the retina - instead it just passes through.  This light is essentially wasted.  In humans, for instance, only about 10% of the light that enters the eye falls on a photosensitive part of the retina, which accounts for our poor night vision.  Many nocturnal animals have a layer behind the retina called the tapetum lucidum.  At night, light enters the eye and hits the retina.  Some of the light hits rods, but a lot of it doesn't, and this light passes through the retina, hits the tapetum lucidum, and is reflected back into the eye, where some of it hits rods.  This increases the clarity of the animal's vision at night, and causes the eyeshine that you see in cats, dogs, deer, and other animals at night.  \n\nHope that helps answer your question.  Here are a few interesting websites that have more info:\n\nhttp://en.wikipedia.org/wiki/Tapetum_lucidum\n\nhttp://en.wikipedia.org/wiki/Night_vision\n\nhttp://www.owls.org/Information/eyesight.htm
918278
Without light you cannot see anything.\n\nWhy?\nBecause the light (which is consist of the colors (V I B G Y O R)\nstrikes an object. Depending upon the object, the light may or may not reflect some of the colors.\n\nWhen an object reflects some light, the object will then have a color.\nFor example, if the object absorbs all the color from the light except red, the red will be reflected to your eyes. This will make you see the color red.\nThat is, a red rose is color red because it reflects rhe color and it goes to your eyes. So you see color red.\n\nWhen an object reflects all light ( none of the color was absorb), then the object will appear white (that is the combinatio of all the colors).\n\nWhen an object reflect only green and blue, the object will appear to your eyes as cyan (correct me if I'm wrong, coz if I'm not mistaken, the combination of green and blue is cyan).\n\nThose object which absorbs all the color that composed the light appears black.\nBecause no light is bouncing back and go to your eyes.\nAnd we all know that black is the absence of any color.
134682
Light is both a wave and a particle at the same time.\n\nLight is a form of energy, and depending on how you observe it, it exibits both properties of an electromagnetic wave or a particle (photon).\n\nElectromagnetic waves do not require a medium in which to propigate, they are a self propigating electric and magnetic field, allowing it to travel through a vacuum.\nEvidence of this can been seen in diffraction patterns, such as when you look at the rainbow effect on a CD.\n\nPhotons are a "quantized" amount of light.  These light partciles are absorbed or given off by atoms in something called the "photoelectric effect" (which Einstien received a nobel prize for).\nEvidence for this can be seen in things like LEDs or when you study the structure of the atom.
551197
Not  necessary. When the thickness is high ordinary ray of light is absorbed by the crystal and only the extra-ordinary light comes out.\n\nIf  cut we can  identify the position of crystal to produce the polaraised light.
546907
sunlight has full spectrum whereas artificial light is limited depending on what kind of bulb you use.