Scientists accurately measure the total amount of matter in the universe for the first time
More than two-thirds of the known universe is made up of “dark energy” with only 31 percent of matter – and most of that is made of “dark matter,” the experts found.
Cosmologists from the University of California, Riverside, used a set of tools and a new “galactic orbit” technique to calculate the amount of matter in the universe.
To calculate this, they first computed matter in a single galaxy by looking at how it orbited around neighboring galaxies, and then expanded it to the entire universe.
The team found that matter makes up 31 percent of the universe, and the rest is made of dark energy – an “unknown form of energy” that scientists have yet to understand.
Of the 31 percent, the majority – 80 percent – are made of dark matter, a substance that we only discover through its gravitational interactions with another substance.
The researchers claim that this is “one of the most accurate measurements ever made using galaxy cluster technology”.
Cosmologists from the University of California, Riverside found that 69 percent of the universe is dark energy, 31 percent is matter and 80 percent is dark matter.
On a global scale, the amount of known matter is negligible, according to the study authors – gas, dust, stars, galaxies and planets make up only 20 percent.
If all of the matter in the universe were distributed evenly across space – it would have “a density equal to about six hydrogen atoms per cubic meter.”
Lead author Muhammad Abdullah said: “However, since we know that 80 percent of matter is actually dark matter, in fact, most of this matter is not made up of hydrogen atoms but from a type of matter that the cosmologists have not yet understood.” .
Cosmologists make it clear that determining how much matter is in the universe is not an easy task, saying it relies on both observations and simulations.
As part of the measurement, the team compared their results to other predictions and computer simulations to obtain a “temperate” character that felt “absolutely correct.”
To estimate the command in a cluster, the team calculated the number for one galaxy based on the way it orbits the others, and then raised that number for the entire group.
Combining galaxy clusters and comparing these calculations with simulations of the expected amount of matter in the universe gave the team the most accurate number ever recorded.
“We have succeeded in making one of the most accurate measurements ever using galaxy cluster technology,” said co-author Gillian Wilson.
This was the first use of the galactic orbit technique – which involves quantifying matter in one galaxy by looking at how it orbits around other galaxies.
Abdullah said, “The higher percentage of the material will lead to more clusters.”
This Hubble image shows a cluster of galaxies – the researchers used information from galaxy clusters like these to calculate the total amount of matter in the known universe
Like Goldilocks, the team compared the number of galaxy clusters they measured with predictions from numerical simulations to determine exactly the right answer.
Abdullah said, “The Goldilocks’ challenge for our team was to measure the number of groups and then determine the ‘completely correct’ answer.
“But it is difficult to accurately measure the mass of any galaxy cluster because most of the matter is dark, so we cannot see it with telescopes.”
Dark Matter: Heavy Glue
Dark matter is a hypothetical matter that is said to make up approximately 31% of the matter in the universe.
The mysterious substance is invisible because it does not reflect light, and scientists have not directly observed it.
Astronomers know it’s there because of the effects of gravity on known matter.
The substance is thought to be the gravitational “glue” that holds galaxies together.
Dark matter is a relatively unknown substance believed to be the gravitational “glue” that holds galaxies together.
Calculations show that many galaxies would rupture rather than rotate if they weren’t held together by a large amount of dark matter.
Unfortunately, it has never been directly observed and can only be seen through its gravitational interaction with other forms of matter.
To overcome this difficulty, astronomers developed GalWeight, a cosmic tool to measure the mass of a galaxy cluster using the orbits of its member galaxies.
The researchers then applied their tool to observations from the Sloan Digital Sky Survey (SDSS) to create “GalWCat19,” a publicly available catalog of galaxy clusters.
Finally, they compared the number of groups in their new catalog with simulations to determine the total amount of matter in the universe.
“The great advantage of using our GalWeight galaxy Orbit technology was that our team was able to determine the mass of each cluster separately rather than relying on more indirect statistical methods,” said third co-author Anatoly Clayben.
By combining their measurements with those of other teams who used different techniques, they were able to determine the best combined value.
The results have been published in The Astrophysical Journal.
Dark Energy: A phrase used to describe a “mysterious thing” in the universe
Dark energy is a phrase physicists use to describe a mysterious “thing” that causes unusual things to happen in the universe.
The universe is filled with matter and the gravitational force of gravity holds all matter together.
Then came 1998 and Hubble Space Telescope observations of very distant supernovae, which showed that long ago, the universe was in fact expanding more slowly than it is today.
So the expansion of the universe isn’t slowing down because of gravity, and as everyone thought, it’s accelerating.
Nobody expected this, and no one knew how to explain it. But something was causing it.
“Not only is the universe expanding, but it is expanding faster and faster over time,” Dr. Cathy Romer, a scientist at the Dark Energy Survey told MailOnline.
“What we were expecting was that the expansion would get slower and slower over time, because it has been nearly 14 billion years since the Big Bang.”
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