Looking at the night sky, it is easy to think that the universe is an endless dark sea. But what is the average color of the universe when you measure the visible light of all the shiny objects there?
Let’s get rid of that first: it’s not black.
“Black is not a color,” Ivan Baldley, professor at the Institute of Astronomical Physics at John Moores University in Liverpool, UK, told Live Science. “Black just has no detectable light.” Instead, the color is the result of visible lightCreated by, across the universe Interpreter When Galaxy, He said.
Related: How many atoms are there in the observable universe?
In 2002, Baldry and Karl Glazebrook, eminent professors at the Center for Astrophysics and Supercomputing at Swinburne University of Technology, Australia, Astrophysics Journal It measured light from tens of thousands of galaxies and combined it into a singular spectrum representing the entire universe.
In doing so, the couple and their colleagues were able to calculate the average color of the universe.
Stars and galaxies Electromagnetic radiation, Divided into different groups according to the length of the transmitted waves. From shortest wavelength to longest wavelength, the group includes: Gamma rays, x-ray, Ultraviolet raysvisible light Infrared radiation, microwave When Radio waves..
Visible light occupies a small portion of the electromagnetic spectrum in terms of wavelength range, but it is all that can be seen with the naked eye. What we perceive as color are actually just the different wavelengths of visible light. The wavelengths of red and orange are long, and the wavelengths of blue and purple are short.
The visible spectrum of stars and galaxies is a measure of the brightness and wavelength of light emitted by stars and galaxies, which can be used to determine the average color of stars and galaxies, Baldley said. .
In 2002, Australia’s 2dF Galaxy Redshift Survey was the largest galaxy survey ever carried out at the time, capturing the visible spectra of over 200,000 galaxies from across the observable universe. By combining the spectra of all of these galaxies, Baldry and Glazebrook’s team were able to create a visible light spectrum that accurately represents the entire universe, known as the cosmic spectrum.
The comic spectrum “represents the sum of all the energies in the universe emitted at different wavelengths of light,” wrote Baldry and Glazebrook without separate peer review. Online paper In 2002 based on their findings. The spectrum of the universe, in turn, allowed them to determine the average color of the universe.
The researchers used a color-matching computer program to transform the cosmic spectrum into a single color visible to humans, Baldley said.
our eye There are three types of photosensitive cones, each helping to perceive different ranges of wavelengths of visible light. This means that there are certain blind spots between these ranges where wavelengths of a particular color cannot be properly recorded, wrote Baldry and Glazebrook in their online journals. The color we see also depends on the standard of white light when we observe an object. For example, objects may look different in bright rooms than outside on a cloudy day.
Related: What color is the sunset on another planet?
Nevertheless CIE color spaceCreated by the International Commission on Illumination in 1931 and used by the team’s computer models to compensate for visual limitations by assigning colors to the different combinations of wavelengths seen by a standardized human observer. to augment.
The team determined that the average color in the universe is a shade of beige, not far from white. This is a rather boring find, but it is surprising considering that white light is the result of the combination of all the different wavelengths of visible light and the cosmic spectrum contains such a wide range of lengths of light. wave. is not.
The new color was eventually named “Cosmic Latte” after a survey of the entire research team, based on the Italian word for milk. Other suggestions included the cosmico cappuccino. big Bang Primitive beige clam chowder.
Release the red shift
An important concept in the cosmic spectrum is that it represents cosmic light “originally envisioned,” Balrdy and Glazebrook wrote in their online journals. This means that it represents the light emitted throughout the universe, and not as it is visible to us. Earth today.
Like all waves, the light Doppler effect.. As the light stretches, its wavelength increases and its color shifts towards the red edge of the spectrum, known to astronomers as redshift. This means that the light we see is not the same color as when it was first emitted.
“We have removed the effects of the redshift from the spectrum of the galaxy,” said Baldley. “So that’s the spectrum of the galaxy when they emit light.”
Therefore, the space lath is the color you see when you can look at the universe from above and see all the light from all the galaxies, stars and gas clouds at once, Baldley said. .
Originally published in Live Science.