***** The civilized world disagrees with you. en.wikipedia.org/wiki/Bacon The USDA defines bacon as "the cured belly of a swine carcass" And you pretending tofu can be sort of made to resemble bacon doesn't make it bacon. If your religion says you can't eat bacon, why on earth would you want to try to make something to imitate bacon? Who do you think you are fooling?
Might be many years too late, but you should also check out Captain Disillusion's video "CD / Color". It has a whole series of animations doing visual representation of what's going on with those diagrams.
Monochromatic violet light is definitely purple-ish looking, in spite of the fact that actual purple is a mix of colours. Violet is not just "dark blue". It's true that you can't properly show violet light on a typical RGB display, so if showing violet on a display, you would fake it with a very bluish purple, because that's the closest you can simulate how we perceive violet without actually creating violet light. Look at a 400nm LED sometime, (often called UV, though it's really just violet). They have no red light in the mix, but definitely look violet (and not blue).
In the inverted color sequences of your video, Henry, how do you get your hand to appear fleshy tones? Fancy editing, or do you just paint your hand blue?
I believe this video misses the fact that high wavelength light appears purple, because our red cones sense some high wavelength light and that combined with the response of our blue cones produces a purple perception. At 2:00 when he says “pure deep violet” he could have said “purple”. What he calls purple is probably magenta.
Yup. If the atmosphere didn't interact with light at all, you'd only see the blackness of space in every direction, except in the direction of the Sun, which would instantly blind you... And thus, you'd get to see even more black!
Yep. It's the reason why the sky is black on the moon. No scattering of light from the atmosphere, means darkness. For an approximation, when you are flying on a plane on a long plane flight, look up (or as up as you can) during the day to see how much darker the sky is compared to the brightness when you are on the ground. Less atmosphere in the way, less scattering, the sky would be darker.
I guess if our eyes were more sensitive on the "blue" end, or the curve would be steeper, the sky would be darker, towards violet (or dark blue). Maybe that is what is happening, as there are individual differences between people and they are just used to their "blue". Would not surprise me as I read somwhere that according to one study some people were able to see frequencies up to 1020 nm, which is in the near infrared part of electromagnetic spectrum. Althought I imagine they were "seeing" only monochromatic IR light of that frequency, and it must have been a very intense light, but they saw just some dim, very dark red and hard to recognize outlines. If they were looking at the full visible light spectrum, the IR fequencies would be effectively blocked by the processing of visible light. Might be interesting though to take part in such an experiment. I would certainly volunteer.
Spectral violet consists of single wavelengths that create a combination of red and blue perceptions in the human visual system. However in a digital camera these wavelengths only affect the short wavelength (Blue) sensor and not the long wavelength (Red) one, so they photograph as deep blue. I don't know why anyone would say that spectral violet is actually a deep blue unless they need to look at a real spectrum instead of relying on photos.
This video answers a question different than the one asked. It answers why there aren't purple hot objects and it gives the wrong answer to both questions. The reason the sky is blue and not purple is the relative sensitivity of the eye to different wavelengths of light and the details of the solar spectrum (which the video does touch upon). The spectrum of the scattered light is a solar spectrum distorted by the scattering process. This process is very inefficient for red light (long wavelength) and much more efficient for blue light (short wavelength). This produces a spectrum that is predominantly blue and purple. The reason that it isn't mostly purple is the fact that the solar spectrum drops off quickly add to that the fact that the human eye is much less sensitive to purple light than blue and we get the blue sky we see. The reason we see a blue sky and not a purple one is the small amount of purple light coupled with the low sensitivity of our eyes to that light.
NoahHasMinecraft No, actually he doesn't. He gives the reason that really hot objects don't look purple. You can see this by noticing that he is referring to thermal spectra and their relationship to perceived color.
I wish I could find an old book that I think was called "A Chemical History of a Candle." It sounds like the book in your ad would remind me of it. It was about all kinds of things that seemed unrelated to me when I read it, but fascinating. Thanks for all your work, :)
It is too bad we cannot produce computer monitors that can stretch farther out into the color spectrum, and also explains why a picture of a black light never truly captures the deep violet color it can produce (pure 400nm wavelength). I wonder if AMOLED displays can actually display a much broader array of colors since the light sources are individual LEDs themselves. Also, what about people with tetrachromatic vision, how do led monitors look to their eyes? If there forth color receptor is, say, yellow, then they will be able to notice a huge difference in color between actual yellow wavelengths of light (like from a prism) and the mixture of red and green most everyone else can see. It would be like the difference between some shade of purplish washed-out yellow and some neon yellow, I'd imagine. (the tetrachromats wouldn't be able to describe the difference to use since they have learned since birth that everything of that basic hue is yellow, so they would not be able to differentiate it by description, even if they did, it would be like tring to describe the difference between red and green to a colorblind person. They do not have any conceptual understanding of those hues.) So in a way we are all colorblind!
I wonder if the developer of those quattron LED TVs had tetrachromatic vision and was bothered by the fact that the yellow he saw on the TV was not anything like she sees in the world... That would make a lot of sense! Now if only media such as videos can carry 4 channels of color data instead of 3, the world would be a better place lol.
Wait, you said that the sun is white hot until the light reaches the atmosphere, then it turns red hot when it diffuses, and leaves blue hot around. But isn't blue hotter than red? So is the light that is scattered through the atmosphere normally higher on the thermal spectrum than the light scattered through the atmosphere during a sunset (When it looks red)? And if the sun is white hot, does that mean it is lower on the thermal spectrum than the blue light in the atmosphere? I'm just a little confused as to where everything falls on the thermal spectrum, and the significance of where they all fall.
tscoffey1 You're right. I think this fallacy is due to the fact that some people can't see violet. Probably the one who said Violets are blue in the poem is one of them. And probably some people who write science (if they didn't just copy it from someone and missing the skeptical eye).
What was considered "violet" back when the colors of the rainbow were listed by Newton, and when that poem was written, is different than what most people refer to as violet today. In the traditional sense Violet is more of what today we would call indigo, while indigo was more what we'd simply refer to as blue today. Think about the visible light spectrum - each color seamlessly blends into the next. How can purple as we perceive it, which is a combination of red and blue light, exist on the opposite end of the visible spectrum from red?
Matthew, I know that since Newton, there is a mix-up of indigo with another color, still today, depending in which circles you resume (painters, scientists, screen builders, ..) but as far as I've read, the mix-up, or the shift, of indigo, is not with violet, but with the "lighter" blue below that. That blue that looks more like the sky on a sunny day (some kind of cyan), which is what Newton defined blue by, but not with the violet above that. As far as I know, violet (the one just under UV, above blue ánd indigo) has never been confused that way, but with another confusion due to R & B (purple) being similar to violet. That's why people think they are the same. It's also difficult to distinguish them when not seeing them together. (And all that besides the fact that some can't see violet.)
Your eyes use 3 receptors on your retina to see color (and to mix colors that don't exist...eg. purple or pink) It uses the blue receptor to see both blue and violet. Purple is a mix of red and blue. There's no such thing as purple...it's blue and red, but our mind perceives purple. Violet is a monochromatic color that stimulates your blue receptor weakly because that blue receptor is most sensitive for the wavelength at 445nm (blue). True monochromatic violet is perceived by your brain as a darker blue because the same receptor is used and it's less sensitive to that wavelength.
Generally the sky isn't blue, more of a tint. In fact those with the general ideal of the sky being blue see it more blue than those who haven't learned "the sky is blue" as a concept. There is a tribe who's language describes blue and green with a single word, and so when presented a blue object and a green object they find little difference in the color of the two. But ignoring physiology and my pedantic nature the video was fascinating.
With all this focus on color perception, I wonder if you could do a video on the opponent color theory. The way we perceive colors is rather complicated and very much not obvious. For instance, why does violet look more similar to purple than to blue if violet light only stimulates the S-cone (blue cone)?
@@carultch As I understand it, violet light stimulates the S cone significantly less than blue light does, but it stimulates the L and M cones only slightly less than blue light, so it seems proportionally more red.
I'm colourblind. That graph of all of the colours which a person can see is actually a graph of all of the colours which a colourblind person can see if you are looking at it as a colourblind person.
YushiMer Assuming no scattering in the way, and nothing to slow the photons, you'd see yourself 20 years in the past - 10 years to the mirror, 10 back to your eyes. It would likely be a bit longer, however, due to the constant expansion of space itself.
Well you would observe the mirror first a bit over 10 years from now, considering the mirror has its own light which it sends. And considering the light we shine is sent from earth and we shine it exactly perpendicular to the mirror with the angle of incidence to the normal being 0, it would reflect directly back. However, it would take us a bit over 20 years (considering the expansion of the universe) for us to first observe the light sent from earth. You'd also have to take into account the intensity of light as the intensity is inversely proportional to the square of the distance. If it is going to take over 20 years to reach back, you'd have to make sure the light is intense enough to be observed. This also includes the fact that the mirror is going to absorb some of the light. Considering the mirror IS going to reflect everything, you'd also have to figure out whether the light you're observing is the one reflected from the mirror, or just the light from a distant source 20 light years away (to put everything in perspective, this may possibly be the easiest part). Furthermore, as light bends due to gravity, you'd have to make sure there are no massive objects in the way to bend the light off it's path. Or, measure exactly how much the light would bend around a massive object and take that into account to ensure no angle of incidence to the mirror. Also the velocity of the objects as they would be at a different position for when the light is reflected back. Or other sources of light with higher intensity which may blind out our observation of our original light source (for example, the light sent from our sun, in which case it would be too bright to be able to observe earth through the mirror). Furthermore, sending a mirror that far is probably impossible given our time of existence. (The furthest we've sent an object is the voyager 1 which is still inside our solar system). You would have to take into consideration the time to get it to reach there, the fuel, objects which may get in the way, equipment being broken, and the cost of everything else which is involved in sending an object to space. And MUCH MUCH more. And that, my friend, is how science ruins people's imaginations. In theory, however, disregarding every other concept of physics and reality, then we would technically be looking 20 years into our past, considering we first shine the light from Earth (10 years there, 10 years back).
A star like Rigel is a go to example of something that is blue-hot, which is a lot hotter than Betelgeuse that is red hot. Most things on Earth that emit light by virtue of their temperature, are only red hot, because they are at the cold end of the spectrum of temperatures where it is possible to emit visible light, so we associate red with hot, and blue with cold, for this reason. A tungsten bulb is yellow-ish white-hot, and that is about as hot as we can get a solid to be so that it emits as much visible light as possible by black body radiation. To get something hotter than this through black body radiation, you'll need it to be in the plasma phase of matter. Gasses usually don't produce blackbody radiation, because they produce their spectral emission lines instead. Lightning is an example of a naturally-existing blue-hot object produced on Earth, and it is in plasma phase of matter.
Deconverted Man as we've seen it all depends on a. The size/age of the star b. The distance from the star to planet c. The size of the atmosphere d. The composition of the atmosphere e. The size of the receivers eye So, any color is possible! Just play with those elements and the color will change.
Deconverted Man If you are just taking into account the Rayleigh scattering, you would only get the colours from the thermal spectrum (basically blue or red) for the reasons the video states. But theoretically, if you had an atmosphere with iodine gas it would be purple! And with chlorine gas, it would be greenish-yellow! And there are probably many more colourful gases.
What color would extrasolar terrestial planets with different atmospheres of different composition and different stars, would the color of their atmospheres look like??? . im planning to make short sci fi stories and i want to be as realistic as possible, thanks.
Can stars be purple? Because I heard that there can be stars that produce light of two different colors at the same part of their life (at the same moment), so what if there is one that produces blue and red at the same time and then it mixes and becomes purple? It would be so cool... XD
No, stars cannot be purple. There is a specific spectrum of light that stars produce by virtue of their temperature. If a star is hot enough to glow blue, it will also produce all the visible light colors, and be a bluish white. No matter how hot you make the star, it will never produce a disproportionately higher amount of violet light, to make it purple. There is a limit to how blue a star can get, from the bluish white color that form stars like Rigel.
I chuckled at that picture of biscuits/gravy at the end there. Oh, the not-so-fond memories of one of every three breakfasts for 5 months of my life...
I just want to say that your audible ad was enjoyable too. I love Bill Bryson and everything I've read of his so far! Everyone should listen to Bill Bryson, on audible.com of course. Gravy sky! :)
Whoa, hold on... I thought the explanation was simply that air scatters blue and violet, but we see the blue much better. Now this color temperature explanation seems entirely different. Are these competing theories or just two sides of the same coin?
l Iove white in conjunction with other colors, especially when it's nicely paired up with royal purple; it's a magnificent combination. I also have an affinity for white, gray, and black together because even colorless schemes have their own unique beauty.
Why is pure monochromatic light graphed around that particular shaped curve? Huge props for explaining (well, *describing*) so much about this graph in such a short time. But like all great answers, it leads to so many more questions! Like, what are the numbers on the axis supposed to represent?
+samramdebest Because showing "all colors" would involve every wavelength (impossible) and every combination of wavelengths (ultra impossible). There are an infinite number of colors. Computers can't handle "infinity".
Monochromicornicopia I meant why computers can't show all visible colors to a reasonable colors. Like if they had theoretical infinite range on the 3 colors they emit. Maybe I meant that not all (visible) colors are expressible as RGB values
+samramdebest A computer can only emit 3 colors. Red, Green, And Blue. All other colors are a combination of those. So if you saw yellow on your screen it isn't technically yellow. It is a combination of other colors to form a fake-yellow or pseudo-yellow.
+samramdebest The simple explanation is that the chromaticity diagram is not a triangle, and remember that the diagram is as Henry says, the colors visible to most humans. When expressing colors as a combination of 3 values, it is only possible to display colors that would be graph-able as a triangle on that chart. Hence at about @0:57 in the video, the "computer monitor gamut" is a triangular subset of the whole graph.
Ok,but why do I see the sky as a different color than my friends? Sometimes it looks really purple and I'm like "Wow look at the sky it's so purple!" And they're like "Wtf no what are you talking about?" I'm not colorblind, I can see all the colors normally, but why does the sky look purple-blue to me?
Oh. In my high school physics class (2008) I clearly remember my teacher saying that if we measured the wavelength of light in the sky, it would be purple, but our eyes perceive it as blue bc they're more sensitive to blue light. Weird.
These videos would be so much better without the evolution propaganda. I saw the other day you made it through a whole video without mentioning such unsupported views... I think you know it's unnecessary.
You know what, Yeah you're right, I wish Minutephysics would stop with the unnecesarry propaganda. I dislike the fact that he claims the sun revolves around the earth, That is totally un-acceptable to my fellow Geocentrist Brethren. And while we're ad it, Jesus never spoke of gravity, keep that witchcraft out of our childrens education!
callieeraee I'm suggesting that the evolutionist view is not supported by observation, but is only supported by fabricated construct of interpretation. Since this video is about observation, it is not consistent to bring up irrelevant theories that are not backed by direct evidence.
A Short History of Nearly Everything by Bill Bryson was the first audio book I ever downloaded, and I still consider it to be one of the best I've ever listened to. I recommend it to everyone! :)
I read Bill Bryson's "A Short History of Nearly Everything" when I was in the hospital in labor and then after my son was delivered. I figured it would be that last chance I'd have to read a grown-up book for awhile. It really passed the time and distracted me from discomfort.
Physics based question for a sci-fi novel: Ok, so this alien fleet is travelling towards Earth. Hubble spots them on 19th January 2015. They are traveling at 1/10 light speed (I know that's nearly impossible given fuel and stuff, but that's the fi part of the sci-fi). How many days ago were they actually at that point in space, how far have they traveled in that time and how far away were they from earth when they were detected? Also, can you tell me how you worked this out? I can work out how long a signal of light would take to get from the object to earth given that they arrive on Earth on the 8th August 2015 (so, for instance, when they send a signal from their ship to earth on the 14th February 2015, it arrives on Earth on the 11th March 2015), but I can't figure out the other way.
OH YES FINALLY!!!! This video taught me a thing I wanted to know, but didn't know how to look up, and corrected me on a thing I was actually telling a friend about earlier today!
i know about the rayleigh's criteria so i get it that violet shoud scatter more but it was explained to me that the reason why we see the sky as light blue was because our eyes were most sensitive to yellowish-green light and as we move to higher or lower frequencies the sensitivity of our cones decreases and since blue was sufficiently scattered as well as had good enough sensitivity that is why we perceive the sky to be blue. is it correct ? also if our eyes were sensitive enough for higher frequencies like violet would the sky look a darker blue then ?
The ad to this video (for me) wasn't a commercial, but a survey by youtube. I think youtube putting out surveys to better their content instead of ads is a cool idea.
I can see violet in a prism. When I was in elementary school I remember the teacher showing us a prism and identifying the seven colors to us. I asked what that 8th color was and pointed at it. She said it was blue. I said, "no, that really thin line right past blue." And she gave me a funny face and then ignore the question and moved on. It wasn't until years later that I learned that it wasn't normal to see 8 colors in a rainbow. It just so happens that I can see a wider range of colors than other people can. Whereas some people are tetrachromatic, having an additional cone oh, I'm not. I just have a larger frequency range. One benefit of this is having Perfect Color acuity. Because I can distinguish a wider frequency band I can see differences in colors that other people can't. So in short, yeah, it is possible to see purple without mixing with other colors. It's just not a common ability. I can't always differentiate between the blue and purple in a rainbow in the sky though for some reason. It is a really thin line to me, so sometimes it's just seven colors. Although, sometimes I even see 14 to 16 color rainbows, as I can occasionally see the colors blending together. That's distinct from the 14 to 16 color rainbows where the color pattern is inverted onto itself for some reason.
Oh! So is the purple sunset sky, which happens mostly over the sea/ocean/water caused by the mix of the light coming from the sky (red/orange) and the light reflected by watersurface (blue) ?
Dekareen That's a violet sky. Nothing to do with ocean etc. There are some errors in the video. He mixes violet with purple. See my long comment for more.
Great explanation on the origins of different colours as mixtures of different portions of monochromatic lights using the chromatographic diagram! And I did learn the reason for why stars are not purple in colour with the thermal spectrum. It might even be better if the effect of scattering by the Earth's atmosphere to the sun's original spectrum is shown at the end. That will be a more explicit way of showing that scattering (by the atmosphere) cannot modify the spectrum in a way that gives the "right" proportion leading to purple/violet, and hence the sky is not purple/violet. Great thanks!
the sky has been purple EVERY SINGLE NIGHT here in michigam, metro detroit to be exact!! at 1:15 you basically said it would take multiple frequencys to see a purple sky? but the sky has been PURPLE, light, dark, deep purple (etc) it's actually really weird? do you or anyone happen to have an explanation for this?
I would like to see a video on the difference between heat and light. I have have heard many people say that heat waves are actually photons (mostly in the infrared frequency range) while others have told me that heat is the amount of vibration of an atom/particle.
So, Henry, when you claim that violet is not a monochromatic color, you seem to be forgetting that monochromatic violet lasers exist... and look purple, not blue. Spectral violet is a real monochromatic colour, despite the couple of videos you made saying the opposite :). There is a second small peak in the sensitivity of our red color receptors in the far blue region, so very short wavelength light gets picked up by both the blue and the red receptors, and looks violet (purple, not blue). Your photos of refracted light won't show this because the red sensors/filters in cameras don't have this second peak in the blue that human red cones have. For a similar reason, computer screens cannot show real monochromatic violet, they have to fake it.
+ninjafruitchilled Yep, I seem to be the only one in the comments who understands you (I like to build lasers). My 405nm (just 5 nm away from ultraviolet) laser is definitely violet and my 445nm laser is blue violet.
Henry: The disclaimer you added @0:59 actually contradicts your claim that the color at the short end is blue. Note that our monitors can only render within that triangle. But note also that it's an exact triangle--the lines are exactly straight. That's because these chromaticity diagrams are such that the linear combination of any two colors on the diagram forms a third color in a straight line. But the blue point on your triangle, projected backwards from white, only manages to hit about 465nm on your diagram. So, sure, we can't render 465nm light's color--but 465nm light blended only with white is perfectly renderable--and becomes blue. In like fashion, how do you imagine we should render 400nm light's approximate color on a monitor? Easy. By taking blue and adding... red. Yeah, I know. It sounds confusing, but it's not as big a deal as you think. L cones don't produce red percepts--rather, ganglia in our eyes adds L and subtracts out M, forming the red-green opponent color process. This moves towards red when L dominates this process and, since M falls off in sensitivity faster than L near the short wavelengths, the process tends back towards red.
I don't think the "violet is essentially blue" argument is correct: if you have ever looked at an hydrogen discharge lamp you will immediately experience with your eyes that violet REALLY is violet (very strongly violet, I would add)...
A hydrogen discharge lamp looks more like magenta to me, which is a mixture of red and blue. It emits red, cyan, and blue, and violet from the Balmer series which add up to approximately magenta. The red line is usually the brightest.
Your videos are very informative and I always end up wish where were you when I was in high school. I have only one request though - can you go a little slow in your narration.. you were way too fast for me to digest what you were saying.
