Black is what we see because it absorbs all other color wavelengths from the light, so it cannot reflect any color. It is not a color but just an absence of any other visible color.
Every other color we see is due to their reflective properties of the surface, which hits back the light at a certain wavelength.
So, an object can be termed black if and when a substantial amount of light comes into contact with it is equally absorbed by the object.
To understand the color black, we need to delve more into the properties of the other seven colors.
The properties of color are intertwined with the workings of light. It all started in the 1660s with the great scientist and mathematician Sir Isaac Newton, he began a series of experiments with sunlight against prisms. He first deduced that clear white light consists of all seven colors thus, inventing the visible spectrum of light, the rainbow.
His ground-breaking experiment challenged various scholarly views on the subject all over the world. Aristotle believed that colors are sent from heaven through celestial rays of light. He suggested that all color come from white and black i.e. the presence of light and darkness. His beliefs were widely accepted until they are broken scientifically by Newton.
Understanding the visible spectrum of light gives us the idea of what black is not. Black thus, defined as a condition where no visible light reaches the eye. Pigments that absorb the light rather than reflecting it back to our eye ‘looks black’. It is the ultimate absorption of all colour.
For we know in color theory there is a primary and secondary division of colours – red, yellow, blue is the primary colour and green, purple, orange is the secondary ones. When we mix primary colours together all we get is black i.e., the condition where little to no visible light is reflected. Thus, proving the theory of absorption of all colours.
In optical science, black is the ultimate consumer of light but in thermodynamics, black is the perfect emitter. As black absorbs every wavelength of visible light it traps heat from all the radiation of different colours.
At every frequency, it reflects more thermal radiative energy than any other coloured material at that temperature. This is why we are suggested to avoid black coloured clothes during summer, as it will absorb maximum light energy and in turn trap heat to make us hotter.
Black thus became much more than just a definition of colour. In astronomy, we name the largest mystery of the universe the Black Hole. A black hole is a region in space-time where gravity is so strong that it even prevents light from escaping. Just like a perfectly black body of thermodynamics. Nobody knows what happens inside a black hole, it forms when massive stars collapse. Outer space is black because there is nothing to reflect back the light, space is a vast nothingness and as we have established absorption of light gives us black. This is why we cannot see the moon during new phase.
Typically, black is another color like red or white but one that is associated with doom, darkness, evil, and death. It’s a different scenario, however, when it comes to physics. Black is the perception experienced by the eyes of a person when there’s the complete absence of light or when there’s total absorption of wavelengths in the existing spectrum.
Black is said to lack a hue, just like the color white, which is a deviation from the norm compared to other colors of the spectrum, making black an achromatic color.
What Is Color
Colors come to exist because of the electromagnetic radiation by varying wavelengths which can be seen by the human eye. What makes colors differ from the other is the brightness, the three qualities of hue and saturation.
Therefore, the electromagnetic radiation with a wavelength that makes color exist needs to have an amount of electromagnetic spectrum called a visible spectrum, which is the light. That’s why for color to be seen, vision is very critical. For instance, when it’s dim, someone can still manage to see only that they won’t be in a position to locate the variation in colors. This can only be made possible in the presence of light. This also means that light needs to be of a certain intensity for colors to appear.
But here is an interesting thing about color. Under the same situation and circumstances, one may see an object as red while the other will see orange. I know we had been told that the light intensity makes a certain color visible, but the mind and its response to visual stimuli also plays a part. This is because when the color perception is determined by light, vision, and individual interpretation, to understand color needs psychology, physiology, and physics.
Now, when you look at an object, and you see a certain color, it’s because of how it has interacted with light. Therefore, analyzing the interactions and digging into the factors that made that possible are what physics and color are all about.
Color psychology is visual data processed by the mind competes with the information that is stored in the memory, which is then interpreted as color.
So to better understand black as per physics, which is the complete absence of light, it’s imperative to know how light travels.
How Does Light Travel…
Light moves in categories known as photons. When the wavelength of the photons is around 650 nanometers comes into contact with the human eye, the color red will appear. Color yellow exists at a nanometer of 570 and do does green, while blue appears at 480 nanometers. White, on the other hand, exists when eyes come into contact with photons of varying wavelengths.
So, a certain color appears because of pigment molecules because while they absorb certain levels of light wavelengths, they do reflect others. Now, when light hits an object, the light wavelength of the object is reflected towards your eyes leading to the color that will be identified.
For instance, the cover of an orange absorbs blue, violet, indigo, green, yellow and red photons but what’s reflected back is the orange photons.
Instances Where Black Physics Applies
What you need to understand is that black materials and paints absorb about 90% to 95% of the light that they come into contact with, which is a good thing. In the world of aerospace, they have black paint known as Z306, which has a 96% light absorption. They use it to paint the inner side of grandiose telescopes, which makes it possible for detectors to spot even the tiniest of light from galaxies at a distance.
Nanotechnology is required if you need to have a proper depth of black. Carbon nanotubes are therefore being used in plenty by researchers for photons tracking. Once the photons get to a surface, nanotubes trap them and make them go round and round until they are devoid of light hence completely black.
NASA has also not been left behind considering they have as they have a carbon nanotube whose coating takes in 99.95% of the light that it comes into contact with, which makes it a deeper shade of black compared to the Z306. Being extremely black, painting it on an aluminum foil makes it appear like a hole. Something interesting about black holes is that they absorb any kind of light.
The black color physics has been applied in various fields like aerospace, where the black coating with a 96% absorbing rate is used on telescopes to help spot small bits of light from afar.
So whereas color in physics can be described as the phenomenon where all colors are absorbed, it’s also the absolute combining of various color pigments. Black is therefore good when it comes to absorbing light and light emission as well. This makes it good when it comes to radioactive cooling in the absence of light.
According to science, ultraviolet rays that can be spotted from a distance can be to as “black light” because it leads to fluorescing of minerals plus other substance.
When you look at the color spectrum, you will not find a wavelength range with the name black on it, and as per Physics, black means that there’s no wave that exists, totally.