More than two-thirds of the known universe is made up of “dark energy” with only 31% made up of matter and most of it is made up of “dark matter,” according to experts.
Cosmologists from the University of California, Riverside, have used a set of tools and a new “galactic orbit” technique to calculate how much matter there is in the universe.
To calculate this, they first processed matter in a single galaxy by looking at how it orbits nearby galaxies, then zoomed in for the entire universe.
The team found that matter makes up 31% of the universe, the rest is made up of dark energy, an ‘unknown form of energy̵
Of the 31%, the majority – 80% – is made up of dark matter, a substance that we only detected through its gravitational interactions with other matter.
The researchers say this is “one of the most accurate measurements ever made using the galaxy cluster technique.”
Cosmologists from the University of California, Riverside, found that 69% of the universe is dark energy, 31% is matter, and 80% is dark matter
On a universal scale, the amount of known matter is minuscule, according to the study’s authors: gas, dust, stars, galaxies and planets make up only 20%.
If all matter in the universe were evenly distributed in space, it would have “a density equal to that of about six hydrogen atoms per cubic meter.”
“However, since we know that 80% of matter is actually dark matter, actually most of this matter is not made up of hydrogen atoms, but rather of a type of matter that cosmologists do not yet understand,” he said. said lead author Mohamed Abdullah.
Determining exactly how much matter there is in the universe is not an easy task, cosmologists explained, saying it is based on both observations and simulations.
As part of the measurement, the team compared the results with other predictions and computer simulations to get a “goldilocks” figure that looked “right”.
To estimate matter in a cluster, the team calculated a galaxy’s figure based on how it orbits others, then scaled it down for the entire cluster.
Combining galaxy clusters and comparing these calculations to simulations for the predicted amount of matter in the universe gave the team the most accurate figure ever recorded.
“We were able to make one of the most accurate measurements ever made using the galaxy cluster technique,” said co-author Gillian Wilson.
This was the first use of the galaxy orbit technique, which involves determining the amount of matter in a single galaxy by observing how it orbits other galaxies.
“A higher percentage of matter would result in more clusters,” Abdullah said.
This Hubble image shows a cluster of galaxies: Researchers used information from collections of galaxies like this one to calculate the total amount of matter in the known universe
Like Goldilocks, the team compared the number of galaxy clusters they measured against predictions from numerical simulations to determine which answer was ‘right’.
“The Goldilocks challenge for our team was to measure the number of clusters and then determine which answer was” right, “Abdullah said.
“But it’s difficult to accurately measure the mass of a cluster of galaxies because most of the matter is dark, so we can’t see it with telescopes.”
DARK MATTER: A GRAVITATIONAL GLUE
Dark matter is a hypothetical substance that is said to make up about 31% of the matter in the universe.
The enigmatic material is invisible because it does not reflect light and has never been directly observed by scientists.
Astronomers know it’s out there because of its gravitational effects on known matter.
The material is thought to be the gravitational “glue” that holds galaxies together.
Dark matter is a relatively unknown substance thought to be the gravitational “glue” that holds galaxies together.
Calculations show that many galaxies would be torn apart instead of spinning if they were not held together by a large amount of dark matter.
Unfortunately, it has never been observed directly and can only be seen through its gravitational interaction with other forms of matter.
To overcome this difficulty, astronomers have developed “GalWeight”, a cosmological instrument for measuring the mass of a cluster of galaxies using the orbits of the galaxies that compose it.
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 clusters in their new catalog with simulations to determine the total amount of matter in the universe.
“A huge benefit of using our GalWeight galactic orbit technique was that our team was able to determine a mass for each cluster individually rather than relying on more indirect statistical methods,” said third co-author Anatoly. Klypin.
By combining their measurements with those of other teams who used different techniques, they were able to determine the best combined value.
The findings were published in the Astrophysical Journal.
DARK ENERGY: A PHRASE USED TO DESCRIBE A ‘MYSTERIOUS SOMETHING’ IN THE UNIVERSE
Dark energy is a phrase used by physicists to describe a mysterious “something” that is making unusual things happen in the universe.
The universe is full of matter and the pull of gravity brings all matter together.
Then came 1998 and the Hubble Space Telescope’s observations of very distant supernovae that showed that, long ago, the universe was actually expanding slower than it is today.
So the expansion of the universe hasn’t slowed down due to gravity, as everyone thought, it’s accelerating.
Nobody expected it, nobody knew how to explain it. But something was causing it.
“The universe is not only expanding, it is expanding faster and faster as time goes by,” Dr Kathy Romer, scientist with the Dark Energy Survey, told MailOnline.
“What we would expect is that the expansion will get slower and slower as time goes by, as it has been nearly 14 billion years since the Big Bang.”