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Does ''light'' give us night vision and allow us to see in the ''dark''?
Quote from: TheBoxDoes ''light'' give us night vision and allow us to see in the ''dark''?Yes.A bit of ''light'' give us night vision and allow us to see in the ''dark''.A lot of ''light'' give us day vision and allow us to see in the ''light''.Too much ''light'' gives us sunburn and (in extreme cases) will blind us so we never see again.
You say a bit of ''light'' gives us night vision
then say a lot of ''light'' gives us day vision
Should it not be that a lot of ''light'' gives us perfect ''night vision''?How can we be sure that day vision is just not perfect night vision?
And what do you mean by ''light''?
we do not see ''light'' in ''empty'' space
How do we know that when we increase the intensity of ''light'' on a thing such as a dimmer switch, that we are not just intensifying our ''night'' vision?
the ''light'' we don't see in space makes space ''gin-clear''
Does anyone disagree with that ''light'' allows us to see in the dark?
[Note that you arn't using opaque in the sense used by most users of English, you clearly have your own definition which doesn't help communication.
opaqueə(ʊ)ˈpeɪk/Submitadjective1.not able to be seen through; not transparent.
I should have added another boundary condition:No ''light'' give us no vision (we are blind).
I would disagree and say that all the space surrounding the laser dot was still ''opaque'', however between our eyes and laser dot the space was ''transparent'' and not opaque.
When I turn out the ''light'' it is dark, relative to me ''dark'' is not ''transparent'' to my sight. ''light'' is needed to make ''dark'' ''transparent''.
I say that all the space surrounding the laser dot was still ''opaque'', however between our eyes and laser dot the space was ''transparent'' and not opaque.
So the question is how do you know you are blind in the dark when the dot suggests there just has to be something to see
It would be quite difficult to ''judge'' the distance the dot was away from you.
Quote from: Thebox on 08/06/2016 17:40:52I would disagree and say that all the space surrounding the laser dot was still ''opaque'', however between our eyes and laser dot the space was ''transparent'' and not opaque. Before we go any further, we need to understand your meaning of opaque. From our dictionary opaque means light will not pass through that area. However, if someone stands to your right or left they will also see the dot so the space cannot be opaque - even by whatever definition you use - because between their eyes and the dot is transparent.
However, if someone stands to your right or left they will also see the dot so the space cannot be opaque - even by whatever definition you use - because between their eyes and the dot is transparent.
My definition variation is - sight will not pass through that area, i.e a rainbow obstructs the vision and is ''opaque'' to sight. Sight will not pass through darkness, the darkness is relatively ''opaque''.
Which shows that we can see in the dark and are not blind there just needs to be light interacting with something that allows us to see that something?
Yes the darkness is transparent and allows light to pass through, even without light the darkness is still transparent , however without light/matter interaction the darkness is ''opaque'', add a little bit of light i.e a dimmer switch, the darkness becomes ''translucent''?
opaque is the closest word I can think of that closely describes what I refer to as ''opaque'
i.e a rainbow obstructs the vision and is ''opaque'' to sight.
This is due to you defining opaque differently to everyone else.We do not consider that sight passes through anything, sight does not move through space, we believe it is light which moves.
In physics, "light" mean electromagnetic waves with wavelengths between 400 and 700 nm, or particles of light (photons).
We do see light passing through empty space, because we see stars, the Sun and the Moon through empty space
My definition variation is - sight will not pass through that area....I do not mean in a sense that there is any travelling involved of/from the eyes.
I must correct you though in that wavelengths between 400-700nm is visible light
wavelengths between 400-700nm is visible light observed as spectral content like the colours of a rainbow
I do not observe visible light between me and the star, I observe invisible light do you disagree with this observation?
So I disagree with your assertion - I see that both visible and invisible light pass freely through empty space (although I need a computer to translate the invisible wavelengths into a wavelength range that my eyes can see).
I have no idea where the rainbow came from - it seems to have come out of thin air. Is it something to do with color vision??But a rainbow does not obstruct light and it is not opaque - it is made of water droplets (transparent) in the air (transparent).
do you or do you not see visible light of 400-700nm passing through space?
would ''you'' then say we was part blind if the dimmer switch was turned down to half of the power giving half the luminosity?
Colour is the only vision we have
Do you see the rainbow is different to the space that surrounds the rainbow?
Yes, I see it.
Since you seem to enjoy pseudo-mathematical malarky, I'll try to represent dark and light, transparent & opaque in pseudo-mathematical terms for you.
Lets assume we have a source of light (eg a laser pointer, a torch or the Sun), which can either be ON (1) or OFF (0).
The amount of light L illuminating the scene can be represented as follows:a) Dark + Dark = Dark; L=0+0=0 (ie dark)b) Dark + Light = Light; L=0+1=1 (ie light)c) Light + Dark = Light; L=1+0=1d) Light + Light = Light; L=1+1=2 (ie very light*)
*This ignores the theoretical possibility of local light cancellation by anti-phase light.
They both give the same answer: They both suggest that the area outside a laser spot is dark.
.....describe your observation of ''empty'' space which you claim to see ''light'' that is in the range of 400nm-700nm.
You see the dot through the dark? which is ''opaque''and ''transparent'' ,
Quite clearly the wavelength's of 400nm-700nm are not observed in ''empty space'' unless we see a rainbow.
Do you still claim to see the wavelength of 400nm-700nm passing through space?
Dark + Dark?
Yes it is dark but the dark is also transparent at the same ''time''. You see the dot through the dark? which is ''opaque''and ''transparent''
Empty space is not a dispersive medium, so we see the visible light (400-700nm) from the Sun and other stars travelling through empty space without forming a rainbow.
Something cannot be both opaque and transparent.
you have not considered x-rays or radio waves that pass through opaque things.
how do you see it if it does not form a rainbow?
I am sure you mean detect it?
But this discussion has mostly been about empty space and air, and these are both transparent to visible light, not opaque.So the lesson here is that transparent air is not opaque.
But when I am talking about my eyes, I talk about seeing the light directly (even if I am looking through the eyepiece of my telescope).
I see ''empty'' space and no spectral content in that space.
how do you see [a star] if it does not form a rainbow?
Quote from: TheBoxI see ''empty'' space and no spectral content in that space.This is where the contrast between transparent and opaque becomes significant.In general:- Something that is transparent does not absorb nor emit light (at that wavelength). You can light from objects beyond it.- Something that is opaque both absorbs and emits light (at that wavelength). You can't see light from objects beyond it.So both empty space and clear air are transparent (to visible light)- They do not absorb nor emit light (at visible wavelengths).- You can see the wall beyond the clear air- You can see the glow of the laser pointer beyond the clear air- The clear air does not emit any wavelengths (spectral content) in addition to those emitted by the laser pointer- You can see that the wall is dark outside the dot of the laser pointer- The wall can "see" (be illuminated by) the laser pointer in your hand, beyond the clear air.- You can see the Moon beyond the empty space- The empty space does not emit any wavelengths (spectral content) in addition to those emitted by the Moon- You can see the Moon and the Wall with no extra rainbow colors.Quote from: TheBoxhow do you see [a star] if it does not form a rainbow?If you look at a rainbow, you will see bands of color. These are "pure" colors (Red, Orange, yellow, etc); you will see 6 of them (if you live in the USA) or 7 (if you live in the UK).If you have a look at the star trails, you will see streaks of many different colors. But these streaks of different color don't come from a single star; each trail is a single color and comes from one star. And none of these streaks are the "pure" colors of the rainbow; these are all mixtures of pure colors, with the exact mixture determined by the temperature of the star.So stars come in many colors, but they don't come in rainbow colors.
You seem to understand clear air because the air has a low refractive index and does not ''compress'' the ''light'' to form visible wavelengths.
We have to have a clear line of sight to observe ''things'', I deem if we do not have a clear line of sight in that such as where a rainbow obstructs the line of sight, the once clear air is now ''opaque'' relative to sight where the rainbow occupies. Our line of sight is obstructed which also shows us that ''something'' is obstructing the ''light''. I am not sure if you understand my ''argument'' about opaque or not?
You seem to understand clear air because the air has a low refractive index
air has a low refractive index and does not ''compress'' the ''light'' to form visible wavelengths.