The question of how much matter the universe contains has long intrigued cosmologists. Scientists believe that only 20% of all the matter that makes up stars, galaxies, atoms, and life is ordinary or baryonic matter. The remaining 80% consists of dark matter, a mysterious substance whose fundamental nature remains the subject of ongoing research and speculation.

To achieve these revolutionary results, scientists from Egypt and Japan used established methods to determine the total matter content in the universe. They carefully compared astronomical data on the number and mass of galaxy clusters per unit volume with estimates obtained by numerical simulations.

The basic principle that guided them in their research was the correlation between the amount of matter and the density of galaxy clusters. Essentially, higher concentration of matter corresponds to greater number of galaxy clusters.

It’s not an easy job

However, directly measuring the mass of these clusters has been difficult because they cannot be directly observed with telescopes. To overcome this obstacle, researchers took an indirect approach. They used the fact that more massive galaxy clusters contain more galaxies than less massive ones. Because galaxies are made up of stars, counting the galaxies in each cluster allowed astronomers to indirectly estimate the total mass of the cluster.

Thanks to this innovative technique, astronomers were able to determine the total mass of each galaxy cluster and then compare it to the model’s predictions. The surprising agreement between their observations and the model’s predictions eventually led to the discovery that: 31% of the universe consists of matter. This result is fully consistent with data from the Planck Observatory, especially regarding residual radiation.

An important aspect of this work is the use of spectroscopy to determine precise distances to each cluster; this distinguishes it from earlier, less accurate methods. The researchers’ use of this method significantly increased the reliability and accuracy of the results obtained.