Light: visible or invisible?

[Rob McEachern]

34 minutes ago, studiot said:

did you not want to discuss the mechanism of the effect

It is based upon a form of FM demodulation, that involves pairs of bandpass receptors (like cone cells) that measure intensity only. Due to the non-flat frequency versus intensity response of the receptors, it is possible to precisely (not accurately!) infer (not measure!) a single input frequency from any ratio of intensities. However, any spectrum of inputs will be "transduced" into a single output inferred frequency. Since red and green of equal intensity yield the same intensity ratio as a single frequency between them, they all are perceived as being yellow. In the case of receptors with Gaussian intensity vs. frequency distributions, it is easy to show that the resulting frequency estimate is exact, when no noise is present.

Edited March 12, 2018 by Rob McEachern
fix typo

[studiot]

2 minutes ago, Rob McEachern said:

It is based upon a form of FM demodulation, that involves pairs of bandpass receptors (like cone cells) that measure intensity only. Due to the non-flat frequency versus intensity response of the receptors, it is possible to precisely (not accurately!) infer (not measure!) a single input frequency from any ratio of intensities. However, any spectrum of inputs will be "transduced" into a single output inferred frequency. Since red and yellow of equal intensity yield the same intensity ratio as a single frequency between them, they all are perceived as being yellow. In the case of receptors with Gaussian intnsity vs. frequency distributions, it is easy to show that the resulting frequency estimate is exact, when no noise is present.

 

So you are saying that the system in the human eye can distinguish between two waves one of 540 nm and one of 541nm ?

[Furyan5]

So, since we all agree that light has no color, how can we see it?

1 minute ago, studiot said:

 

So you are saying that the system in the human eye can distinguish between two waves one of 540 nm and one of 541nm ?

540nm is the wavelength, not the amplitude.

[studiot]

2 minutes ago, Furyan5 said:

So, since we all agree that light has no color, how can we see it?

 

I think you are the only person who agrees this.

 

 

[Rob McEachern]

8 minutes ago, studiot said:

So you are saying that the system in the human eye can distinguish between two waves one of 540 nm and one of 541nm ?

According to the wiki entry for Color vision:

"the just-noticeable difference in wavelength varies from about 1 nm in the blue-green and yellow wavelengths, to 10 nm and more in the longer red and shorter blue wavelengths."

[beecee]

32 minutes ago, Furyan5 said:

That's your opinion. Nothing more, nothing less. 

As is your rather pedant philosophical take just your opinion.

 

30 minutes ago, StringJunky said:

Or: Orange is a result of the reflective selective properties of the object

AGREED. 

[studiot]

1 minute ago, Rob McEachern said:

According to the wiki entry for Color vision:

"the just-noticeable difference in wavelength varies from about 1 nm in the blue-green and yellow wavelengths, to 10 nm and more in the longer red and shorter blue wavelengths."

So how does this help our discussion?

 

[Furyan5]

11 minutes ago, studiot said:

 

I think you are the only person who agrees this.

 

 

Actually, you're the only one who disagrees and thereby, holding everyone back.

You're excused!

[Rob McEachern]

1 minute ago, studiot said:

So how does this help our discussion?

It answered your question. In some parts of the spectrum, human eyes can indeed distinguish wavelength changes as small as 1 nm. In others, they cannot.

[koti]

The only reason that the human eye can see the visible spectrum is because specific wavelengths of light stimulate the retina in the human eye. The rest is overthinking or nonsense. 

[Furyan5]

13 minutes ago, beecee said:

As is your rather pedant philosophical take just your opinion.

 

AGREED. 

Agreed, but my opinion doesn't contradict itself. My opinion doesn't claim we can see size-less, colourless and incredibly fast EMR.

1 minute ago, koti said:

The only reason that the human eye can see the visible spectrum is because specific wavelengths of light stimulate the retina in the human eye. The rest is overthinking or nonsense. 

Opinion. Again.

[studiot]

2 minutes ago, Rob McEachern said:

It answered your question. In some parts of the spectrum, human eyes can indeed distinguish wavelength changes as small as 1 nm. In others, they cannot.

 

Only in very specific lighting and observation conditions.

Equally it can be done only in some parts of the spectrum, but to follow string junky's line in others they cannot.

Orange in particular lies in this zone.

 

This discussion has become polarised into two camps.

Those who insist that the retinal image is not seeing but the brain model is, and those who hold the reverse.

 

I really can't see why we can't all agree that seeing is a general term that can be and is widely used to denote either or both of these.

From this the logical action is to use new terms, (detect and perceive are as good as any) when we need to make the distinction clear.

However I have also just shown where see has yet another meaning (understand).

Perhaps there are more still?

[Rob McEachern]

1 minute ago, koti said:

The only reason that the human eye can see the visible spectrum is because specific wavelengths of light stimulate the retina in the human eye. The rest is overthinking or nonsense.

Then why do you suppose that you cannot see the visible solar spectrum, like the absorption lines in the sun's visible spectrum? More specifically, taking into account my previous post that in some parts of the spectrum, you can just barely distinguish wavelength shifts as small as 1 nm, why can't you perceive spectral lines of that width? The answer is well known to others, but apparently not to you; it is the difference between how frequency spectrum analyzers work and how frequency demodulators (like FM radio receivers) work.

[studiot]

24 minutes ago, Furyan5 said:

Actually, you're the only one who disagrees and thereby, holding everyone back.

You're excused!

 

I'm sorry someone was not impressed with this post so let's lay the underlying misconception to rest.

 

You can no more say that light has no colour than you can say that a bowl of water has no temperature.

 

In each case a part of your body can be used to estimate the physical quantities we use to measure these properties and in each case these days we have more accurate and sensitive machines to also perform this task.

Edited March 12, 2018 by studiot

[Rob McEachern]

28 minutes ago, studiot said:

You can no more say that light has no colour than you can say that a bowl of water has no temperature.

That is not true. Color is entirely constructed, within your brain, from measurements of intensities. In other words, it is constructed from counting the number of photons received in three different frequency bands (in normal humans). And these photon counts are modified (such as via white balance in a digital camera) to make the color of every perceived object, depend not just on the properties of the object in question, but on all the surrounding objects as well (in an attempt to account for the spectrum of the illuminators). This last point was the reason for my first post above ; if you prevent the visual system from "seeing" the surrounding scene, it may dramatically change the color the brain assigns to an object within the scene.

Edited March 12, 2018 by Rob McEachern
clarification

[koti]

26 minutes ago, koti said:

The only reason that the human eye can see the visible spectrum is because specific wavelengths of light stimulate the retina in the human eye. The rest is overthinking or nonsense. 

 

15 minutes ago, Rob McEachern said:

Then why do you suppose that you cannot see the visible solar spectrum, like the absorption lines in the sun's visible spectrum? More specifically, taking into account my previous post that in some parts of the spectrum, you can just barely distinguish wavelength shifts as small as 1 nm, why can't you perceive spectral lines of that width? The answer is well known to others, but apparently not to you; it is the difference between how frequency spectrum analyzers work and how frequency demodulators (like FM radio receivers) work.

I have used spectrophotometers in my work and I’m fairly versed on how they function. How did you come to a conclusion that I need to know the difference between a frequency spectrum analyzer and a radio eludes me. Its nice to know that you know things though, congratulations.  Now if you would like a second try to comment on my above post you’re welcome to do so, maybe this time your comment will correlate with my statmement. 

26 minutes ago, Rob McEachern said:

That is not true. Color is entirely constructed, within your brain, from measurements of intensities. In other words, it is constructed from counting the number of photons received in three different frequency bands (in normal humans). And these photon counts are modified (such as via white balance in a digital camera) to make the color of every perceived object, depend not just on the properties of the object in question, but on all the surrounding objects as well (in an attempt to account for the spectrum of the illuminators). This last point was the reason for my first post above ; if you prevent the visual system from "seeing" the surrounding scene, it may dramatically change the color the brain assigns to an object within the scene.

This thread is not about color perception.

[Rob McEachern]

6 minutes ago, koti said:

Now if you would like a second try to comment on my above post you’re welcome to do so, maybe this time your comment will correlate with my statmement. 

Try "over thinking" about my question about why you cannot resolve spectral lines even though you can perceive shifts in wavelength comparable to line-widths. There is more to seeing than what meets the eye.

[koti]

1 minute ago, Rob McEachern said:

Try "over thinking" about my question about why you cannot resolve spectral lines even though you can perceive shifts in wavelength comparable to line-widths. There is more to seeing than what meets the eye.

No thank you. I’m just fine with perceiving shifts in wavelenghts and I’ll stick to that. 

[Rob McEachern]

1 minute ago, koti said:

No thank you. I’m just fine with perceiving shifts in wavelenghts and I’ll stick to that.

To each his own.

[beecee]

1 hour ago, Furyan5 said:

Agreed, but my opinion doesn't contradict itself. My opinion doesn't claim we can see size-less, colourless and incredibly fast EMR.

Opinion. Again.

Of course it does! And not only contradicting, but resorting to unnecessary and irrelevant pedant and philosophy, and at the same time discriminating between word definitions like perceived, see, and interpret. Our eyes see...period: Unless of course in the first instance, no part of the visible spectrum falls on the eye, thereby giving us a perception of colour. And those facts lead us to the logical conclusion, that an Orange in the dark, has no colour.

[beecee]

2 hours ago, beecee said:

 Our eyes see...period: Unless of course in the first instance, no part of the visible spectrum falls on the eye, thereby giving us a perception of colour. And those facts lead us to the logical conclusion, that an Orange in the dark, has no colour.

Very badly worded! Can I have another go?  Our eyes see...period: Unless of course in the first instance, no part of the visible spectrum falls on the eye, thereby giving us a perception of a lack of colour, or black. And those facts lead us to the logical conclusion, that an Orange in the dark, has no colour. 

[koti]

2 hours ago, beecee said:

Very badly worded! Can I have another go?  Our eyes see...period: Unless of course in the first instance, no part of the visible spectrum falls on the eye, thereby giving us a perception of a lack of colour, or black. And those facts lead us to the logical conclusion, that an Orange in the dark, has no colour. 

I think both of your statements are clear and ofcourse correct. I wonder how many more times this can be repeated then misinterpreted, rephrased and repeated over and over again in a loop of insanity. 

[Furyan5]

I will say this only once. You're confusing the Orange you see (which is the mind model) with the Orange (outside our bodies) which reflects light. The mind only creates the mind model if our eyes detect (not see) light coming from the 'outside' orange. 

If, as you claim, we see light, then we don't see objects. Only light is visible and objects are invisible. According to your claim, oranges are invisi ble. 

This is the contradiction 

[koti]

15 minutes ago, Furyan5 said:

 

If, as you claim, we see light, then we don't see objects. Only light is visible and objects are invisible. According to your claim, oranges are invisi ble. 

This is the contradiction 

Its exactly that, there is no contradiction. How much longer will it take you to understand that when we see an object, we only see light. We see objects only by perceiving light which bounces off of them or is being emitted by them. Oranges are invisible without light, you actually wrote something which makes sense, too bad you think its incorrect. 

Edited March 12, 2018 by koti

[Furyan5]

9 minutes ago, koti said:

Its exactly that, there is no contradiction. How much longer will it take you to understand that when we see an object, we only see light. We see objects only by perceiving light which bounces off of them or is being emitted by them. Oranges are invisible without light, you actually wrote something which makes sense, too bad you think its incorrect. 

How much longer will it take you to realize the we 'see' objects, when our eyes 'detect' light. We perceive the object, we infer the light. 

Detecting light is part of the visual process but the purpose of vision is to allow us to see things. Seeing things gives us an evolutionary advantage. 

Our retina detects light that strikes it. Seeing is the ability to perceive an object without making physical contact with the object. If light must 'strike' our eyes to be detected, that is not seeing. That's feeling. 

We detect light. We see objects.