Light: visible or invisible?

[Furyan5]

45 minutes ago, StringJunky said:

The impulse created by the photon interacting with a receptor. He could've easily just said 'signal'.  It's not too difficult to work out what he meant.

Apparently not. He seems to think electrochemical impulses are a form of light. 

47 minutes ago, koti said:

Retina contains neuron photoreceptors (rods & cones) which translate light into signals which travel through the neural pathways into the brain. So yes, in short - eyes send light into the brain. It’s not my belief, its well established science.

Photo-electric transduction is exactly that. The conversion of light into electrical impulses. It's the 'electrical impulses' which travel from the eye to the brain. Not light. 

[koti]

27 minutes ago, Furyan5 said:

Apparently not. He seems to think electrochemical impulses are a form of light. 

Photo-electric transduction is exactly that. The conversion of light into electrical impulses. It's the 'electrical impulses' which travel from the eye to the brain. Not light. 

I suggest you read my post more carefuly to deduce what I think. This has been mowed in this thread in countless posts, and no I do not think that there is a fiber optic cable running from the eye to the brain. I also do not think that signals from the retina traveling through retinal neurons to the brain (there are layers of neurons in the retina) are light, that would be ridiculous. Also light does not have to be present in order for the signals to be interpreted by the brain as visual experience (narcotics for example) All this has been already discussed in previous posts, I suggest you read this whole thread thoroughly and come back when you have something useful to add other than nit-picking. I’m sure everyone will be stunned to find out about new aproaches to answering the OP question.

[Furyan5]

5 hours ago, koti said:

I suggest you read my post more carefuly to deduce what I think. This has been mowed in this thread in countless posts, and no I do not think that there is a fiber optic cable running from the eye to the brain. I also do not think that signals from the retina traveling through retinal neurons to the brain (there are layers of neurons in the retina) are light, that would be ridiculous. Also light does not have to be present in order for the signals to be interpreted by the brain as visual experience (narcotics for example) All this has been already discussed in previous posts, I suggest you read this whole thread thoroughly and come back when you have something useful to add other than nit-picking. I’m sure everyone will be stunned to find out about new aproaches to answering the OP question.

No thanks, I'm good. As long as you're not implying that the eyes send actual light to the visual cortex, I don't have a problem. 

[Eise]

20 hours ago, Furyan5 said:

We already have a word for see2. It's called detecting. We detect light. We don't see light. We see objects because our eyes detect light. 

Maybe you are right. But by making artificial new words I tried to keep emotional attachments to meanings of words out. It is a strategy that most of the time works, but not with everybody, not always... 

19 hours ago, Strange said:

When you look at a page of writing, it all appears to be there, fully formed. But that is an illusion created by the brain. They did an experiment where they used eye-tracking so that only the word you are looking at is displayed, the rest of the text is replaced with X's or nonsense.

Yes, that is one form* of 'change blindness'. Daniel Dennett describes his own experience, with him as guinea pig in such an experiment. The eye tracker was attached to his head, and when he felt OK he said 'you can put the system on now'. The answer was: 'it is already on, Dan!'. 

*Another form of change blindness: tell me your experiences. How long before you discovered the change?

The short 'break' between the two pictures is the equivalent of the saccades of the eye

10 hours ago, StringJunky said:

The brain does some serious photoshopping. We have a blind spot in each eye with no receptor cells there and we never notice them normally because our brain photoshops  a continuation of whatever is around the blind spot into it.

Does it? Let's make a (very!) primitive model of the visual cortex. It is like a screen, that assigns an RGB-value to every 'pixel' (nerve cell?) inside the limits of the visual field. Nearby the middle however, the 'pixels' do not get any signal from the eye, because of the blind spot, and 'no signal' of course means 'black'. That black spot has to be photoshopped away.

Now a little less primitive model: there are no nerves from the blind spot (per definition) so there are also no nerve cells in the visual cortex that are eagerly waiting to get input from the eye, from the blind spot. Where is nothing, there is nothing. And where there is nothing, nothing must be photoshopped away.

Being conscious of absence is not the same as absence of consciousness... (That one is not from me of course. Dennett again.)

The same might hold for change blindness.

Edited March 1, 2018 by Eise

[Furyan5]

8 hours ago, koti said:

 

Maybe you are right. But by making artificial new words I tried to keep emotional attachments to meanings of words out. It is a strategy that most of the time works, but not with everybody, not always... 

Obviously it won't always work. From a neuroscience perspective the word 'see' has a very distinct definition, whereas in physics, it has a very generic definition. 

In physics, to see means, to detect with the eyes. The 'visible light spectrum' is the light we can 'see'. Objects make light visible. Unfortunately, the conclusion of this way of thinking is that this makes objects 'invisible' as all we ever 'see' is light. We infer objects.

In neuroscience, to see means to consciously perceive. The 'visible light spectrum' is the range of light 'by which we see'. Light makes objects visible. Objects are visible and we infer light. 

The question "Can we see light" doesn't belong in the physics section. Sight is a neurological process. You can't answer it without touching on neuroscience and if you DO, you get banned. But neuroscience isn't philosophy. It's science, just not physics. 

[koti]

24 minutes ago, Furyan5 said:

The question "Can we see light" doesn't belong in the physics section. Sight is a neurological process. You can't answer it without touching on neuroscience and if you DO, you get banned. But neuroscience isn't philosophy. It's science, just not physics. 

You're welcome to report this thread to the mods if you feel it is in the wrong section.

[Furyan5]

7 minutes ago, koti said:

You're welcome to report this thread to the mods if you feel it is in the wrong section.

Why on earth would I do that? 

[koti]

5 minutes ago, Furyan5 said:

Why on earth would I do that? 

 

41 minutes ago, Furyan5 said:

The question "Can we see light" doesn't belong in the physics section.

 

[Eise]

37 minutes ago, Furyan5 said:

You can't answer it without touching on neuroscience and if you DO, you get banned.

No, no, I am sure that was not the reason. Just stay on topic, polite and friendly, and you will have no problem being banned. Let's test if I get banned:

As most people here say that it is a semantics question, so not an empirical one, it is not a scientific question at all. It is a philosophical question.

Seems we plead that the question belongs to our domain of expertise: one says it belongs to physics (where we still are), you say it belongs to neuroscience, and I think it belongs to philosophy. Can't we all drink a beer together? (Ups, Cape town is far away...)

[Furyan5]

19 minutes ago, Eise said:

No, no, I am sure that was not the reason. Just stay on topic, polite and friendly, and you will have no problem being banned. Let's test if I get banned:

As most people here say that it is a semantics question, so not an empirical one, it is not a scientific question at all. It is a philosophical question.

Seems we plead that the question belongs to our domain of expertise: one says it belongs to physics (where we still are), you say it belongs to neuroscience, and I think it belongs to philosophy. Can't we all drink a beer together? (Ups, Cape town is far away...)

Lol plus you need water to make beer. We're running a bit low on water atm. 

Well philosophy is a broad field. You're allowed to discuss physics and neuroscience, under philosophy. I don't have a problem with that. 

29 minutes ago, koti said:

 

 

My opinion. Unlike others, I don't force my opinion on others. 

[koti]

2 hours ago, Eise said:

Can't we all drink a beer together?

I don’t know Eise, if you promise to keep the lights on? I got a family you know  

[Furyan5]

On 02/02/2018 at 2:22 PM, studiot said:

 

Yes I agree that the OP restricted his discussion to light which enters the eye.

Since that is the only light he discusses, that must be the light he states quite clearly, although you did not underline it, that we never see.

So the issue arise of does the light that enters the eye and forms some sort of image on the retinal constitute seeing or was he intending the creation of a mental model to be included.

He was not clear and may even have meant something else entirely that neither you nor I have thought of.

I have already demonstrated the some complications with the mental model interpretation the most important being the colour blindness tests where the hidden symbol is there and seen at the retinal stage but invisible in the mental model.

 

As a matter of interest, yes this is an old thread and the correct proceedure would have been for the hijacker to have started a new thread, perhaps stating that it was inspired by this one.

By coincidence I was asked another technical question in another old thread last night and I am collecting information to do just this and start a new thread in answer.

I did actually try starting a new thread, saying just that. Unfortunately I wasn't allowed to post it. Thanks Swan

On 16/02/2018 at 10:16 PM, koti said:

Why would you want to define seeing as seeing the reflected light when we see by perceiving both reflected and emitted light straight at its source? Its like saying that the number 24 is a 2 from now on and start to draw conclusions from this. 

For one simple reason. Light has no color. Therefore it's impossible to see red light from an Apple. We see a red apple because our eyes detect 700nm light. 

You* are right Area54, I do tend to be emotional and Im sure it does constrain my comprehension skills at times... it enables me at times as well.

*I used the word „You” to refer to the person called Area54 on this forum.

 

[koti]

@Furyan5 You inserted your own statement into between what I said and quoted me on it making it look like I said it.  This is unnacceptable, I’ve reported this to the moderators and I’m refraining from commenting for the sake of the thread untill mods take care of this.

[Furyan5]

1 minute ago, koti said:

@Furyan5 You inserted your own statement into between what I said and quoted me on it making it look like I said it.  This is unnacceptable, I’ve reported this to the moderators and I’m refraining from commenting for the sake of the thread untill mods take care of this.

Sorry. I just posted my answer under the relevant point. I'm using a phone, so I'm still getting used to how this site works. 

On 15/02/2018 at 1:36 PM, Eise said:

Yes, you did: See1 = See2. 

I think the only argument against my distinction is that it is practically useless. That's fine. But it does not really help to answer the OP.

Do you think we disagree on semantics or on physical processes? When it is semantics, how would you flesh out these semantic differences? 

 

The problem, as I see it, is a lack of understanding how vision works. People wrongly assume we see 'an external' reality. Based on this belief, see1 and see2 have no difference. Comprehending that the 'reality' we perceive is 'an internal representation' of 'outside reality' is key to understanding the difference between see1 and see2. When our eyes 'detect' (see1) light, our brain creates images of the objects 'from which the light originates. We perceive (see2) these representations. We don't consciously see1. What we can see2,  is brightness and colors, which are both visual sensations created by our brain. Not actual light, but representations of light. 

[Butch]

Gee whiz... Photons are messengers carrying information in the form of waves, our eyes detect the photons that strike our retinas, our nervous system carries this information to our brains where we distinguish color and direction vector of the photon. Interestingly we can be easily fooled... frequency and direction can be distorted even to the point where we have no comprehension of the information.

[beecee]

In the first instant, we see because of the EMS of the EMR that enters the eye. Whatever information the nervous system takes to our brain, eg colour, depends on the exact type of EMR that has entered the eye. eg: Q;  What colour is an Orange in the dark? A: It is black and lacks any colour. From that simple reasoning I can deduce that [1] part of the EMR that has entered the eye, is visible, and [2] the exact colour depends on the exact wavelength of the EMS that has entered the eye.

Whatever perceptions/signals etc that the eye and its nerves send to the brain, is dependent on those points.

[Butch]

5 minutes ago, beecee said:

In the first instant, we see because of the EMS of the EMR that enters the eye. Whatever information the nervous system takes to our brain, eg colour, depends on the exact type of EMR that has entered the eye. eg: Q;  What colour is an Orange in the dark? A: It is black and lacks any colour. From that simple reasoning I can deduce that [1] part of the EMR that has entered the eye, is visible, and [2] the exact colour depends on the exact wavelength of the EMS that has entered the eye.

Whatever perceptions/signals etc that the eye and its nerves send to the brain, is dependent on those points.

The orange is orange, even in the dark because it has the property of reflecting orange light. Just because we cannot see it does not change its properties... Unless we are talking about a cat in a box.

[beecee]

20 hours ago, Butch said:

The orange is orange, even in the dark because it has the property of reflecting orange light. Just because we cannot see it does not change its properties... Unless we are talking about a cat in a box.

Sure it has the property of reflecting the orange part of the EMS, but if the EMS is absent, it reflects nothing and is black: Black of course being the absence of colour. Again, in the first instant, the colour of any object depends on what part of the spectrum is falling on it.

[John Cuthber]

10 minutes ago, beecee said:

in the first instant,

When was that, or do you mean the first instance?

[beecee]

26 minutes ago, John Cuthber said:

When was that, or do you mean the first instance?

I stand corrected....first instance it is. 

38 minutes ago, beecee said:

Sure it has the property of reflecting the orange part of the EMS, but if the EMS is absent, it reflects nothing and is black: Black of course being the absence of colour. Again, in the first instant, the colour of any object depends on what part of the spectrum is falling on it.

Just found an interesting and apt description of light and colour here....

http://www.physicsclassroom.com/class/light/Lesson-2/Visible-Light-and-the-Eye-s-Response

excerpt from link.......

"If the appearance of yellow is perceived of an object when it activates the red and the green cones simultaneously, then what appearance would result if two overlapping red and green spotlights entered our eye? Using the same three-cone theory, we could make some predictions of the result. Red light entering our eye would mostly activate the red color cone; and green light entering our eye would mostly activate the green color cone. Each cone would send their usual electrical messages to the brain. If the brain has been psychologically trained to interpret these two signals to mean "yellow", then the brain would perceive the overlapping red and green spotlights to appear as yellow. To the eye-brain system, there is no difference in the physiological and psychological response to yellow light and a mixing of red and green light. The brain has no means of distinguishing between the two physical situations.

 

In a technical sense, it is really not appropriate to refer to light as being colored. Light is simply a wave with a specific wavelength or a mixture of wavelengths; it has no color in and of itself. An object that is emitting or reflecting light to our eye appears to have a specific color as the result of the eye-brain response to the wavelength. So technically, there is really no such thing as yellow light. Rather, there is light with a wavelength of about 590 nm that appears yellow. And there is also light with a mixture of wavelengths of about 700 nm and 530 nm that together appears yellow. The yellow appearance of these two clearly different light sources can be traced to the physiological and psychological response of the eye-brain system, and not to the light itself. So to be technically appropriate, a person would refer to "yellow light" as "light that creates a yellow appearance." Yet, to maintain a larger collection of friendships, a person would refer to "yellow light" as "yellow light."

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Edited March 10, 2018 by beecee

[Butch]

3 hours ago, beecee said:

Black of course being the absence of colour. Again, in the first instant, the colour of any object depends on what part of the spectrum is falling on it.

Black being the absence of any reflective properties (reference black bodies).

[beecee]

3 hours ago, Butch said:

Black being the absence of any reflective properties (reference black bodies).

Or simply an Orange in a room with no  EMS to reflect.

[Furyan5]

On 3/10/2018 at 1:07 AM, beecee said:

In the first instant, we see because of the EMS of the EMR that enters the eye. Whatever information the nervous system takes to our brain, eg colour, depends on the exact type of EMR that has entered the eye. eg: Q;  What colour is an Orange in the dark? A: It is black and lacks any colour. From that simple reasoning I can deduce that [1] part of the EMR that has entered the eye, is visible, and [2] the exact colour depends on the exact wavelength of the EMS that has entered the eye.

Whatever perceptions/signals etc that the eye and its nerves send to the brain, is dependent on those points.

Black isn't a color and neither is orange. They are both hues. Color is a property of an object, which causes it to absorb or reflect certain wavelengths of light. Properties don't change. An orange in a dark room is orange in color and has a black hue. Hue is a visual sensation created by our brain in response to the wavelength of light our eyes do or do not detect. 

[beecee]

1 hour ago, Furyan5 said:

Black isn't a color and neither is orange. They are both hues. Color is a property of an object, which causes it to absorb or reflect certain wavelengths of light. Properties don't change. An orange in a dark room is orange in color and has a black hue. Hue is a visual sensation created by our brain in response to the wavelength of light our eyes do or do not detect. 

Black is the absence of colour.....Orange is a result of the reflective properties of the object, both of course depending on what part of the EMS, or lack thereof, that is falling on that object. The orange in the dark room [ or where there is no visible part of the EMS] therefor has no colour or is black, and its properties to absorb and/or reflect are not in question, and are simply  "inoperable" [for want of a better word] in such circumstances.

 

 

Edited March 11, 2018 by beecee

[John Cuthber]

20 hours ago, Butch said:

Black being the absence of any reflective properties (reference black bodies).

The Sun is a pretty good approximation to a black body.

This is also true of Rigel- which is blue, and Betelgeuse- which is red.

23 hours ago, beecee said:

.

"If the appearance of yellow is perceived of an object when it activates the red and the green cones simultaneously, then what appearance would result if two overlapping red and green spotlights entered our eye? Using the same three-cone theory, we could make some predictions of the result. Red light entering our eye would mostly activate the red color cone; and green light entering our eye would mostly activate the green color cone. Each cone would send their usual electrical messages to the brain. If the brain has been psychologically trained to interpret these two signals to mean "yellow", then the brain would perceive the overlapping red and green spotlights to appear as yellow. To the eye-brain system, there is no difference in the physiological and psychological response to yellow light and a mixing of red and green light. The brain has no means of distinguishing between the two physical situations.

 

 

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It gets more complicated if someone gets a white spotlight and sets it up to shine a ring of white light round the yellow spot.

The yellow spot looks brown.

Of course, none of this matters because (at last according to some people), we can't see light.