What exactly the Universe is made up of is a bit of a mystery, but scientists have for the first time calculated the amount of matter in the cosmos. By creating a new simulation, known as GalWeight, experts were able to determine matter and energy make up 31 percent of the Universe.
This would mean the remaining matter is something known as dark energy.
Astronomer Mohamed Abdullah of the University of California Riverside (UCR) and the National Research Institute of Astronomy and Geophysics in Egypt, said: “To put that amount of matter in context, if all the matter in the Universe were spread out evenly across space, it would correspond to an average mass density equal to only about six hydrogen atoms per cubic meter.
“However, since we know 80 percent of matter is actually dark matter, in reality, most of this matter consists not of hydrogen atoms but rather of a type of matter which cosmologists don’t yet understand.”
Dark energy is an elusive substance which is a complete mystery.
Astronomy news: Scientists measure precise amount of matter in Universe
Dark energy is an elusive substance which is a complete mystery
However, what is known is that it drives the expanse of the Universe, and acts as anti-gravity, pushing galaxies farther apart.
By determining the amount of dark energy in the Universe, experts have a better grasp of the cosmos’s past evolution and where it is heading in the future.
To find the result, experts from the UCR and the National Research Institute of Astronomy and Geophysics in Egypt analysed the mass of galaxy clusters.
The amount of clusters, which are stuck together through gravity, is a good indication of how much matter is present, according to the research published in the journal Astrophysical Journal.
Mr Abdullah said: “A higher percentage of matter would result in more clusters.
The scientists examined galaxy clusters
“The ‘Goldilocks’ challenge for our team was to measure the number of clusters and then determine which answer was ‘just right.’
“But it is difficult to measure the mass of any galaxy cluster accurately because most of the matter is dark so we can’t see it with telescopes.”
To overcome the challenge, the scientists used their GalWeight, which measures the mass of a galaxy cluster using the orbits of its member galaxies, and cross-referenced it with observations from the Sloan Digital Sky Survey (SDSS) which provides information on how many galaxy clusters are out there.
Co-author Gillian Wilson, a professor of physics and astronomy at UCR, said: “We have succeeded in making one of the most precise measurements ever made using the galaxy cluster technique.
“Moreover, this is the first use of the galaxy orbit technique which has obtained a value in agreement with those obtained by teams who used noncluster techniques such as cosmic microwave background anisotropies, baryon acoustic oscillations, Type Ia supernovae, or gravitational lensing.”