Brief Summary
In this video, physicist Marc Séguin explains the concept of color through the behavior of light and photons. He describes how light, made of tiny packets of energy called photons, interacts with our eyes to produce color perception. The video covers the roles of different types of cone cells in the retina, how specific objects absorb and reflect light frequencies, and how this leads to our perception of various colors. Key points include:
- Light consists of photons that oscillate at different frequencies.
- The human retina contains three types of cone cells that respond to specific light frequencies.
- Color perception is a result of how these cones react to different frequencies emitted or reflected by objects.
Marc introduces the topic of color by first explaining light, which is essential for the perception of color. Light is composed of photons, which are tiny packets of energy that travel at the speed of light and oscillate, producing different frequencies. These frequencies range from 450 to 750 trillion oscillations per second for most visible light emitted by sources like the sun or light bulbs.
In the human retina, there are millions of tiny photon detectors known as cones, which are responsible for color perception. There are three types of cones—referred to as teams A, B, and C—each sensitive to different light frequencies. Team A is most responsive to photons oscillating at 500 trillion times per second, team B at 550 trillion, and team C at 650 trillion. The varying responses of these cones help the brain to interpret colors.
An object's color is determined by the specific frequencies of photons it reflects. For example, a strawberry reflects photons oscillating around 500 trillion times per second, stimulating team A, which leads to the perception of red. A lime reflects frequencies around 550 trillion, activating team B and resulting in green. Meanwhile, blueberries reflect frequencies around 650 trillion, activating team C and leading to blue color perception.
The video further explains that while humans have three types of cones that allow for the perception of a wide range of colors, the interplay of these teams can produce additional colors. Objects can absorb certain frequencies while reflecting others, creating a spectrum of colors. For instance, a banana reflects light in a way that activates both teams A and B, leading to the perception of yellow or orange, depending on the intensity of the responses.
Color is not inherent to objects but is a mental perception created by the brain based on signals from the cones in our eyes. Some creatures only have one type of detector and can see light and dark but not colors, reflecting a simpler visual system. Color vision serves practical purposes in nature, such as identifying ripe fruit. The closing observation points out that color televisions, despite using only red, green, and blue technologies, can reproduce a wide range of colors due to the design corresponding with human vision.
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Transcript
Full transcript of “Color Only Exists In Your Brain!”. Click a timestamp to open the video at that moment. Need another video? Use the YouTube transcript generator.
0:02 hi my name is Mark and I'm a physicist like all physicists my goal is to understand things at the most basic level possible today I want to talk to you about color but first I'll have to tell you about light because color is something you see and you don't see anything when there's no light light is created by light sources like the sun or light bulbs it is made of tiny packets of energy called photons photon Suns travel very fast at the speed of light but they also sort of vibrate as they move or if you prefer they oscillate the number of oscillations that a photon completes every second is called its frequency photons oscillate at different
0:47 frequencies for instance most photons emitted by the Sun or light bulbs have frequencies in the range between 450 and 750 trillion oscillations per second 1 trillion is 1 million million so photons can vibrate really really fast in your retinas the screen at the back of each of your eyeballs you have millions of tiny Photon detectors called cones when they detect photons they react by producing signals that are pre-processed in the retina itself then sent to the brain for further processing there are three teams of cones let's call them teams a b and c because they have different chemical compositions they react differently to photons of different
1:33 frequencies cones in team a react the most to photons that oscillate 500 trillion times per second if the frequency is a little bit above or below this value they still react but less and if the frequency is much larger or much smaller they don't react at all cones in Team B react the most to photons that oscillate 550 trillion times per second and cones in team C prefer photons that oscillate 650 trillion times per second we are now ready to understand why a particular object has a particular color let's start with a strawberry it is made of chemical compounds that absorb photons of most frequencies but it contains no compounds that absorb photons that oscillate about 500
2:18 trillion times per second so these photons are reflected enter your eyes and react strongly with the cones in team a when this happens the signal that is sent to your brain results new seeing red by a complicated process that is not yet fully understood a lime contains different chemical compounds and a strawberry it absorbs photons that have frequencies below 500 and above 600 trillion oscillations per second and reflects photons that oscillate around 550 trillion times per second exactly what's needed to excite the cones in Team B so they react strongly and the signal that is sent to the brain results in you seeing green a blueberry absorbs most photons but reflects those that oscillate about 650
3:05 trillion times per second so this time it's team C that reacts strongly and the result is that you see blue there are objects like sugar cubes that reflect most photons at all frequencies when these photons enter your eyes the cones of all three teams react strongly and produce signals when this happens the result is that you see white so even though we have only three teams of cones we can see more colors than just red green and blue for instance the pet of a banana absorbs most photons that oscillate more than 600 trillion times per second and reflects most photons in the range 500 to 550 trillion ocations per second so both teams A and B react strongly this combined signal does not
3:51 result in you seeing red and green at the same time but in a new perception yellow when both teams A and B react but a reacts slight more than b you see orange if only teams A and C react you see purple and so on different objects reflect different combinations of frequencies and this results in all of the wonderful colors we see in the world by some estimates human beings can distinguish between several million colors but it is important to keep in mind that objects and light itself are not by themselves colored color is a mental perception you see color because of the the way your eyes and brain are constructed some animals have a much simpler retina with only one team of detectors they can distinguish between
4:38 light and dark but see no color they see the world in black and white so color is a special effect added on what you see by your brain with the help of three teams of special detectors in your eyes and what a beautiful special effect it is it's also useful in our modern world and also in nature for instance color vision allows us to easily recognize ripe fruit among the leaves of a tree I will leave you with one interesting observation that you can make if you photograph the screen of a color TV through a magnifying glass you will see that it consists only of red green and blue light emitting regions yet the screen can reproduce any color visible to the human eye because it's made especially for human beings with the Tre
5:24 colors of its light emitting regions corresponding to the three teams of cones in human eyes aren't science and technology wonderful [Music]
