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Here I was looking to learn some new art technique through various mediums in the 19th century.
Is there a youtube channel that reviews rare books
Several, I have enjoyed the content from https://www.youtube.com/@tomwayling
Great Thank you
This article gets the colours wrong. Do the red figure example for yourself. If you do it correctly you will clearly see cyan, which is the opposite of red in RGB . It has nothing to do with the "primary colours" of blue and yellow mixing. Basic science facepalm from Smithsonian it seems.
I think there is more to it than a simple "facepalm". In the modern RGB model, green and blue are primary colors, and mixed together, you get cyan, the opposite of red. So the explanation is generally correct, the only thing wrong is that yellow is considered a primary color instead of green.
But look here, and remember the book was published in 1864: https://en.wikipedia.org/wiki/Complementary_colors
Look at the color wheels of that period and earlier, especially this one: https://commons.wikimedia.org/wiki/File:Color_star-en_(terti...
.svg){kind=link}
And you see that red is the opposite of green. Why not cyan? I don't know. I guess cyan simply wasn't a well recognized color back then, maybe cyan was called green (a blueish green). Maybe our perception changed with the availability of modern pigments and screens.
As for the color you see when trying the illusion, it is even more interesting because it is actually an impossible color! [1] It doesn't correspond to a wavelength of light or a combination thereof, you can only perceive it through an illusion like this one. If we follow the Wikipedia article, and considering that the afterimage appears on a dark background that would be "stygian cyan". Spooky! Again, the theory was probably unknown in 1864.
> Why not cyan? I don't know.
Because tradition, and the pigments they used. Red, yellow, blue worked great.
It's a common mistake thanks to people learning in school that the "primary colors" are red, yellow and blue but the explanation is mostly right otherwise: you see cyan because it's a mix of blue and green, i.e. what you get when you subtract red from white light.
Of course human visual perception is a bit more complex than that but the primary mistake here is mixing up RGB and RYB. Quirks of color perception then result in referring to the resulting color as "green" when it clearly contains blue.
Also, the whole idea that "green" and "blue" are different things is culturally determined -- many languages either use one word that contains the shades English speakers call "blue" and "green" or did so historically before introducing separate words after they were influenced by English or other languages that make the distinction.
https://en.wikipedia.org/wiki/Blue%E2%80%93green_distinction...
Doesn't the eye have distinct perceptors for green and blue, or am I missing something?
No. There are three types of cone cells (S, M, and L) that are most responsive to various wavelengths of light, but as the picture shows, most "colors" are within the high and low ranges of more than one type of cone.
For those who downvoted this, did you read the wikipedia entry? Seriously, the idea that many languages don't make a blue/green distinction is a fact.
The classic example is Homer's "Wine-dark sea", but it gets a lot more complicated than that https://en.wikipedia.org/wiki/Linguistic_relativity_and_the_...
The title is also wrong. It's more "... to show that mediums could fool you easily."
> Prove That Ghosts Were Simply an Illusion
This is false. The only thing it proves is that ghosts CAN BE an illusion. Failure to recognize the difference between the two is why such books haven't stopped people believing in ghosts.
>> Prove That Ghosts Were Simply an Illusion
> This is false.
It's not false, that's just the headline.
The book targeted a very specific illusion that con artists would use to scam people. That did prove the ghosts being presented as real were in fact illusions.
> It's not false, that's just the headline
It is false, and it's also not just the headline.
> That did prove the ghosts being presented as real were on fact illusions.
Again, this is false. It proved only that illusory facsimiles of ghosts are possible. You cannot prove that someone didn't see a ghost just because there are non-ghost mechanisms for people to think they're seeing ghosts. That's not how proving things works.
Wouldn't the failure to recognize be more like the cause of why so many people believe that it is a knowable fact that there are no ghosts (and various other "supernatural" phenomena)?
Are any facts knowable? Besides the fact that something exists, in some shape or form, at this particular moment, that allows the thought about this to happen.
Also that, yes. But I do see a space where the authors (and subsequent article writers) recognizing and acknowledging the limitations of proof would help them frame their arguments in such a way that they ultimately convince more people of not having seen actual ghosts.
It's knowable in a sense that hallucination/scam is vastly more probable than an actual ghost (or any other supernatural phenomena).
If there is a mistake in common knowledge, it's the belief that hallucinations/delusions happen only to mentally ill people or on drugs.
You are missing a critical point. Before this, there was likely no proof that people could share or rely on to question if _any_ ghost could be an illusion.
This is very important to future critical thinking because this gave people evidence to back up being skeptical for future illusions that they can't immediately explain.
I agree that it's important to advance knowledge of what's possible, but that is very different from proving a negative.
When I see a card magic trick, for all intents and purposes it "appears" magic. Once I learn _one_ card trick, I start to realize it's not magic. Regardless if I can prove anything or not.
This same applies here with ghosts. People needed to know they _could_ be fooled, how it was done doesn't matter, because people were being scammed and were afraid of things that weren't ghosts.
Proving something is a ghost has never been done, so ghost scams is a good thing to educate people on.
Do you ever notice how in Internet arguments people switch between logic and rhetoric seamlessly to support their argument?
In a very real sense, it is a lot like watching children (with their intelligence limits) arguing, thinking what they say makes sound sense.
This phenomenon is everywhere, including the most powerful places, and it is essentially not even on humanities radar.
I've never seen of a convincing proof that anything exists nor that anything does not exist.
'prove' simply needs not to be taken literally in this context. You can replace it here by 'make a suggestion that'
Many of life's problems can be avoided by using the words that actually mean the thing you're trying to say rather than the ones that don't.
You'll create plenty of new problems in life, too, if you are so committed to being rigid at all times.
Yes, well, some of us are cursed with hearing the words you say and not hallucinating different imaginary ones. I'll leave it to you to decide for yourself whose fault it is that not everyone pretends to be psychic.