Weirdest/things that blew your mind when you learned them

[sysprog]

Your post #90 in this thread was in my view an especially nice post @Klystron.

 

[pleeb]

Years ago I bought a book on Lagrangian mechanics specifically because I was interested in wrapping my head around gyroscopes. It didn't necessarily work, but it did get me to appreciate Lagrangian mechanics.

Color doesn't exist. Only the totally color blind see the world as it really exists. Maybe that's why B&W photography is so fascinating.

 

[sysprog]

Years ago I bought a book on Lagrangian mechanics specifically because I was interested in wrapping my head around gyroscopes. It didn't necessarily work, but it did get me to appreciate Lagrangian mechanics.

Color doesn't exist. Only the totally color blind see the world as it really exists. Maybe that's why B&W photography is so fascinating.

In my non-colorblind view, this is nonsense; color is part of the visual information; that's why our retinas have cones, along with all those rods.

The point that @collinsmark raised regarding gyroscopes and Lagrangian mechanics has nothing to do with color or black-and-white vision. It was about the development of his intellectual vision by his being appreciative regarding something newly learned. That seems to me to be on-topic in this thread.

Your preference for 'noir et blanc' may be worthy of expression, but was not responsive to the post that you quoted.

 

[Merlin3189]

I can't remember exactly when I learned about shunt wound motors speeding to destruction when they lost their field current. May not have blown my mind, but I was pretty sceptical and took a lot of convincing.

I'm reminded by it's popping up in a thread today with someone else who can't believe it.

 

[pleeb]

In my non-colorblind view, this is nonsense; color is part of the visual information; that's why our retinas have cones, along with all those rods.

The point that @collinsmark raised regarding gyroscopes and Lagrangian mechanics has nothing to do with color or black-and-white vision. It was about the development of his intellectual vision by his being appreciative regarding something newly learned. That seems to me to be on-topic in this thread.

Your preference for 'noir et blanc' may be worthy of expression, but was not responsive to the post that you quoted.

You're quite correct, we have cones that give us the illusion of color. But nothing is actually colored. We simply interpret shades of gray as color. There is only light and the absence of light to various degrees. Are you a tetrachromat?

 

[BillTre]

You're quite correct, we have cones that give us the illusion of color. But nothing is actually colored. We simply interpret shades of gray as color. There is only light and the absence of light to various degrees.

Well, only grey scales of different frequencies (which are real), which the brain codes as different colors (to represent that reality).
The fact that natural selection has selected for these mechanisms gives credence to that reality as well as its significance to the organism's survival.

 

[sysprog]

You're quite correct, we have cones that give us the illusion of color. But nothing is actually colored. We simply interpret shades of gray as color. There is only light and the absence of light to various degrees. Are you a tetrachromat?

That's just plain wrong. @BillTre beat me to it, but color perception is not just grayscale being interpreted as color. For example, there's a real and measurable difference between infrared and ultraviolet light even though we can't see either of those. I imagine that you don't suppose that the differences between the frequencies of EMR from your lightbulb and those that cook your food in your microwave oven are merely grayscale variation illusions.

 

[Dr_Nate]

I like to show my students a visible spectrum and ask them to point out where the color white is. Then I show them that their minds are tricking themselves(?) by using a handheld spectroscope and looking at the emission lines from white fluorescent lights.

 

[Dr_Nate]

From walking my dog at night, I learned that I can tell from a distance whether the colour from xmas lights are made from two different LEDs or not, or whether a car's brake lights are incandescent or an LED. I think it has to do with persistence of vision and the pulse rate of LEDs.

I just flutter my eyes back and forth. For brake lights, I can see dots for the LEDs and a line of red for the incandescent. I never took apart someone's brake lights to truly confirm it, but I think it's true because I think I tell the difference normally. For the xmas lights I see dots of different colour that when added together would produce the colour I normally see.

 

[Keith_McClary]

I just flutter my eyes back and forth.

Jocelyn Bell Burnell, who co-discovered the first pulsar PSR B1919+21 in 1967, relates that in the late 1950s a woman viewed the Crab Nebula source at the University of Chicago's telescope, then open to the public, and noted that it appeared to be flashing. The astronomer she spoke to, Elliot Moore, disregarded the effect as scintillation, despite the woman's protestation that as a qualified pilot she understood scintillation and this was something else.

 

[Dr_Nate]

Jocelyn Bell Burnell, who co-discovered the first pulsar PSR B1919+21 in 1967, relates that in the late 1950s a woman viewed the Crab Nebula source at the University of Chicago's telescope, then open to the public, and noted that it appeared to be flashing. The astronomer she spoke to, Elliot Moore, disregarded the effect as scintillation, despite the woman's protestation that as a qualified pilot she understood scintillation and this was something else.
View attachment 260602

Thanks, I had never heard this anecdote before. I'll have to check out the Crab Nebula sometime.

 

[sysprog]

From walking my dog at night, I learned that I can tell from a distance whether the colour from xmas lights are made from two different LEDs or not, or whether a car's brake lights are incandescent or an LED. I think it has to do with persistence of vision and the pulse rate of LEDs.

I just flutter my eyes back and forth. For brake lights, I can see dots for the LEDs and a line of red for the incandescent. I never took apart someone's brake lights to truly confirmed it, but I think it's true because I think I tell the difference normally. For the xmas lights I see dots of different colour that when added together would produce the colour I normally see.

The fastest fast-twitch muscles in the body are those that you use for this purpose: "I just flutter my eyes back and forth" -- such fluttering eyes can move fast enough to cause perturbation from the normal frame rate of visual processing -- that can allow you distinguish visual inputs the differences between which might otherwise be not perceived.

 

[pleeb]

Well, only grey scales of different frequencies (which are real), which the brain codes as different colors (to represent that reality).
The fact that natural selection has selected for these mechanisms gives credence to that reality as well as its significance to the organism's survival.

Agreed; it's how sighted organisms distinguish dangers, poisons, threats, and mates. When I was young I could read only 5 of the 38 Ishihara color plates other than the two neutral standards. Now that I'm in my seventies I can't read any of them. I had no idea I was RG color blind until I was tested when I joined the army, the doctor falsified my record so I could enlist. It was the Vietnam era and they took anybody they could.

 

[Dr_Nate]

Agreed; it's how sighted organisms distinguish dangers, poisons, threats, and mates. When I was young I could read only 5 of the 38 Ishihara color plates other than the two neutral standards. Now that I'm in my seventies I can't read any of them. I had no idea I was RG color blind until I was tested when I joined the army, the doctor falsified my record so I could enlist. It was the Vietnam era and they took anybody they could.

I was told that colour blind snipers are less fooled by camouflage and are thus more valuable.

 

[pleeb]

I like to show my students a visible spectrum and ask them to point out where the color white is. Then I show them that their minds are tricking themselves(?) by using a handheld spectroscope and looking at the emission lines from white fluorescent lights.

But aren't they just seeing frequencies of what we call light? For instance; why is there no magenta in a rainbow? Birds, insects, and fish in the dark zone see in the UV spectrum but they still see colors although sunlight doesn't penetrate the depths. All heating coils produce the same hue of red. I'm no physicist but I can still do research and I've yet to find any claim of innate color on any object. Astrophysicists claim the sun is green, but I've never seen that. I grew up under a yellow sun, millennials have never seen a yellow sun due to the atmospheric changes in gas composition. Superman's powers came from our yellow sun, isn't it odd that his cultural influence waned when the sun turned white? Is our atmosphere filled with kryptonite now? LMAO!

 

[Ibix]

I've yet to find any claim of innate color on any object

The reflectivity of an object as a function of frequency is certainly an objectively measurable thing, as is its emission spectrum. So is the frequency spectrum of the light incident on the object and any filtering between the object and you, although these aren't properties of the object. So the frequency spectrum of light incident on your eyes from an object is a measurable and meaningful thing, over and above the intensity. Neither spectrum nor overall intensity is purely a property of the object, at least in general. I think it's difficult to claim that one is more real than the other.

To me, the only question is whether "green" is only a name for your sensation of your mid-wavelength photoreceptors being stimulated, or also for light that does that stimulating.

Aside: some of the old Star Trek novels had Klingons having vision in the yellow-to-near-ultraviolet range. Thus they see Starfleet's redshirts as clad head-to-toe in black...

 

[pleeb]

I was told that colour blind snipers are less fooled by camouflage and are thus more valuable.

I'd do a fact check on that. In fact, I did and it's not true. 20/20 vision or better is what you'd need. That, and good peripheral vision. And night vision. Colorblind people are more sensitive to bright light and even a rifle flash can produce black or purple spots in their eyes. Artillery flashes can temporarily blind them. If the sun is rising behind their target, forget it. In my day the military wouldn't take you if you're colorblind.

 

[Dr_Nate]

To me, the only question is whether "green" is only a name for your sensation of your mid-wavelength photoreceptors being stimulated, or also for light that does that stimulating.

To expand on @Ibix 's good answer: your brain can be stimulated to perceive green by having photons of around 440 nm be absorbed by your cones, or have only two wavelengths corresponding to red and blue photons be absorbed in the right ratio on the same area of your retina.

 

[Jarvis323]

Maybe the existence of tree Kangaroos; why has nobody told me about this until now?

 

[Ibix]

To expand on @Ibix 's good answer: your brain can be stimulated to perceive green by having photons of around 440 nm be absorbed by your cones, or have only two wavelengths corresponding to red and blue photons be absorbed in the right ratio on the same area of your retina.

Fair enough - I was just meaning to distinguish between colour being a word that labels a sensation versus being one that labels the stimulus (or stimuli, as you note) that causes the sensation. It seems to me to be a matter of semantics, at least if one is claiming that an object is or is not "really" a particular colour. If the colour only labels the sensation then the light isn't green, it just has a spectrum that causes you to perceive green. If the colour also labels the light and/or an object that sends that light to you then the light and the object are green.

 

[Jarvis323]

Also, that animals seem to use quantum entanglement for sense of smell, and to sense magnetic fields.

And also that humans, apparently, are also "selectively processing directional input from magnetic field receptors,”

https://www.popularmechanics.com/science/a31755545/humans-detect-earth-magnetic-field/

 

[sysprog]

The so-called 'wholphin' (I generally dislike portmanteau words) who is a fertile offspring of 2 closely related species, the so-called 'false killer whale' and a dolphin, has 66 teeth -- the arithmetic mean average between the 88 teeth of her dolphin father and the 44 teeth of her false-killer-whale mother.

I was trying to discuss this remarkable macro-emergence from a micro-(DNA-level)-fact with a Chinese woman who was a comp-sci PhD candidate, and I said that I thought that it was interesting that the 2 species were far enough apart that their offspring were usually infertile, but yet they were close enough that in this rare instance, the offspring was fertile.

To clarify the point to the nice gal, I said that this was unlike a horse and a donkey, who are close enough to have offspring together, but not close enough to have fertile offspring.

She said, "well, horse, he have a bad eye, so he don't know that's not a horse".

That was pretty much the entirety of her response.

 

[sysprog]

I'd do a fact check on that. In fact, I did and it's not true. 20/20 vision or better is what you'd need. That, and good peripheral vision. And night vision. Colorblind people are more sensitive to bright light and even a rifle flash can produce black or purple spots in their eyes. Artillery flashes can temporarily blind them. If the sun is rising behind their target, forget it. In my day the military wouldn't take you if you're colorblind.

I was completely colorblind for about a month or so 'way back in the day'. Then I began to see red clearly. Shortly thereafter I was able to experience the full range of colors.

Spoiler: early

Neonates are colorblind. Red comes first. Then the other colors arrive in all their splendor.

 

[Dr_Nate]

For instance; why is there no magenta in a rainbow?

I don't know how to describe magenta, but if we pick brown instead we might be able to just call it dark orange. Perception is a tricky thing.

 

[sysprog]

I don't know how to describe magenta, but if we pick brown instead we might be able to just call it dark orange. Perception is a tricky thing.

Conventionally, you can specify ordinary 'magenta' or 'fuchsia' with 24 bits of RGB accuracy as #FF00FF (max red, no green, max blue).

 

[Klystron]

In my experience the military thoroughly checks recruit's vision including color perception in order to match people with appropriate occupations. The USAF and USN required electronic technicians with excellent color discretion in order to distinguish markings on resistors and the oft-dramatized 'red and green wires'.

I trained and worked with an excellent but partially color-blind tech who had methods to overcome this slight disability. He was originally trained and operated as a photographic analyst with success. Apparently good color vision was not required to distinguish rocket launchers from steam pipes in high speed fly-over photos. His ability to recognize distant aircraft through telescope images was amazing, along with selecting targets from 'grass' (noise) in raw radar returns.

The color blind PF member's insistence that color remains an illusion corresponds to comments from other people who see the world in shades of grey. One color blind brother-in-law, a successful city editor at large newspapers, understood the majority fascination with color but with an amused skepticism similar to discussing an obscure philosophy or belief system. He conceded that other people valued color but dismissed the concept with a sports analogy. A talented quarterback can distinguish movement and angles on the playing field and throw a pass (or kick a soccer ball) down field far better than he; but he still enjoys watching the game.

 

[sysprog]

@Klystron In HS electronics the prof, who had a PhD in propulsion systems, taught us a somewhat awful mnemonic for the BBROYGBVGW resistor color codes -- I think I shouldn't repeat it here.

 

[Merlin3189]

... your brain can be stimulated to perceive green by having photons of around 440 nm be absorbed by your cones, or have only two wavelengths corresponding to red and blue photons be absorbed in the right ratio on the same area of your retina.

A mixture of red and blue light (yes pleeb, light is coloured!) will give the sensation of a shade of magenta. A redish colour like orange and a bluish colour like cyan might give a very desaturated greenish white.
Some saturated greens can be approximated only by mixtures of greens which are already very close to that green.

What may be confusing, is that colour names are very broad categories. Many colours which we would call "green" are easily discriminable. We can tell they are different, but call them all green.

... we have cones that give us the illusion of color. But nothing is actually colored.

I would suggest the opposite: most macroscopic objects are coloured. You don't even need colour vision to see this. A red object and a green object which looked similar to a monochrome camera when illuminated with a white light, would look very different when illuminated with red or green light. That is due to the properties of the object, not the camera.

If you want an interesting account of colour properties of objects, Why Things Are Coloured is a comprehensive and very understandable site.

We simply interpret shades of gray as color. There is only light and the absence of light to various degrees. ...

There is the prescence to various degrees of lights of different colours.
Your view seems rather like trying to do chemistry while believing that all atoms are equal. Water is 3 atoms, methane is 5 atoms,: their differences are due to the presence or absence of atoms to various degrees, ignoring the differences between atoms.

... All heating coils produce the same hue of red. ...I've yet to find any claim of innate color on any object. ...

Depends on the temperature. Hot objects have a broad spectrum, whose peak moves as the temperature rises. The subjective hue also shifts with temperature.

Look at the Why Things Are Coloured site, if you want to find a claim of innate colour of objects.

To be fair to you, the colour of an object that we see, is also dependent on the illumination, but that doesn't mean it isn't determined by properties of the object. We usually think of objects in terms of their colour in broad spectrum daylight, but are aware that this can be changed say under narrow band low pressure sodium street lights, where everything is a shade of yellow. This is all predictable from the properties of the object.

What is less predictable is how humans see colour in context. This could be regarded as a deficiency of our vision. I think we could build robots who were not fooled by context and saw light objectively.

 

[BillTre]

the colour of an object that we see, is also dependent on the illumination, but that doesn't mean it isn't determined by properties of the object.

It has occurred to me that objects with the color most tied to their composition are fluorescent.
Although fluorescence depends upon an exciting illumination in order to fluoresce, but the single wavelength they emit is a function of their emitting molecules which do not change much (unless they are over-illuminated and get oxidized or otherwise chemically modified).
They can however, be quenched by neighboring molecules that can absorb their emitted wavelength.

 

[sysprog]

Well, as long as we're being specific, aren't the stimulated emitters more precisely the atoms rather than more coarsely the molecules?