The Universe's Dominant Color Is Not Black, But...

 


During the day, the sky will be a bright light blue. Then it turns as the sun goes down to orange. And, the night turns black. The question is, what is the most dominant color in the universe?


The phenomenon is related to the scattering of sunlight by gas particles in Earth's atmosphere. This phenomenon is also known as Rayleigh scattering.




Basically, black is not a color. Black in the electromagnetic spectrum indicates that each spectrum is mostly absorbed entirely by objects and cannot escape, nor be reflected back by these objects.







In other words, black is the absence of light that can be detected by our sense of sight or other optical instruments. What's more, the large enough distance between the stars is not enough to make the star look as bright as the center of the solar system on Earth, namely the Sun.


What we perceive as color, is basically the electromagnetic spectrum that is reflected back to our eyes, which in our eyeball are three cone cells and one rod cell.


All four are located in the retina at the back of our eyeball. Each of these cone cells is sensitive to three colors: red, green and blue. Meanwhile, rod cells are sensitive to low light intensity. A similar principle is applied by optical devices that use charge-coupled devices or CCDs, a kind of sensor that functions to capture images.


Each electromagnetic spectrum has its own wavelength. The visible light spectrum or the visible spectrum, including one of the electromagnetic spectrum that can still be observed by the human eye.


The wavelength range is between 400-700 nanometers (1 nanometer = one billionth of a meter). Red has a larger wavelength, which is 700 nanometers, while purple has a shorter wavelength, which is 400 nanometers.


Wilhem Wien in the late 19th century found that the greater the temperature emitted by a black body (an object that absorbs all electromagnetic radiation without any light escaping), the wavelength when the radiation energy is maximum becomes smaller.


If this concept is applied to stellar spectroscopy (the study of the physical properties of stars based on the light they emit), then red stars (larger wavelengths) tend to be cooler than blue stars (shorter wavelengths) which are hotter.


Nearly two decades ago, Ivan Baldry and Karl Glazebrook of Johns Hopkins University, Maryland, United States collected light samples from 200,000 galaxies emitting different spectra and processed them into a computer program that could determine the average single spectrum of the universe. , also known as the cosmic spectrum.



This cosmic spectrum is then perceived as the most dominant color in the universe, if all the stars in the universe can be observed by the human eye at the same distance from Earth.


The spectrum emitted by each galaxy has been pre-processed by eliminating the redshift or Doppler effect on electromagnetic waves because each galaxy is quite far from Earth, so that the spectrum sampled is the spectrum emitted directly from the galaxy. instead of the spectrum received by observers on Earth.


Initially, they both thought the cosmic spectrum or the most dominant color in the universe was turquoise/turquoise (fairuz/turqoise). After being traced, it turned out that a calculation error was found in the program that was made, so it was corrected to beige. This cream color is the most dominant color in the universe which is then given the name cosmic beige or the official name cosmic latte, named after the color of latte (coffee milk/cafe au lait) which tends to be cream.


Andi explained that cosmic beige is still the dominant color in the universe. However, the cosmic spectrum which initially tends to be blue is not entirely inaccurate either. The universe and its contents are always changing.


When stars first formed, they tended to be bluish in color so that the dominant color in the universe was blue. Over time, the stars will dim and swell into red giants. The color that dominates the universe will increasingly shift towards red.


When all the stars in the main sequence (except red dwarfs and brown dwarfs) evolved into red giants, the single dominant color of the universe was red. When this red giant explodes into a supernova and produces a black hole, the color that dominates the universe is black because all the light has been completely absorbed by the black hole and will not escape.

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