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Why Scientists' Latest Dark Matter and Dark Energy Calculations Matter

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In 1998, scientists stumbled upon a surprising cosmic fact. Not only is the universe expanding, they realized, but it seems acceleration Over the years, it has been accelerated by a force we cannot see.

This mysterious effect would soon become known as dark energy, one of the biggest puzzles in physics.

It would equally or even more complement the confusing aspect of our universe called dark matter; A comprehensive concept that scientists first proved in 1933 to explain anything that makes up the hidden, halo-like barriers that prevent galaxies from simply breaking apart. (Another force that we cannot grasp with the human eye.)

However, although we cannot grasp the elusive nature of dark matter and dark energy through sight, we can measure it with mathematics. And on Wednesday, in a series of papers in the Astrophysical Journal, astrophysicists have succeeded in setting the most definitive boundaries ever on the composition and evolution of our universe, including the dark universe.

Using a powerful analytical mechanism called Pantheon+, the team found that about two-thirds of the cosmos is made up of dark energy and one-third of matter mostly in the form of dark matter. More specifically, they suspect that 66.2% of the universe appears as dark energy, with the remaining 33.8% belonging to both dark and visible matter.

Even more exciting than the conclusion of Pantheon+, its operation may be its mind-blowing way. In short, the team used a series of powerful, cosmic flashlights to look back in time and document the contents of the universe as it was more than 10 billion years ago.

By “lanterns” I mean a Type 1a supernova.

These stellar bursts are so bright that they outshine entire galaxies and are therefore visible billions of light-years from Earth. They’re just like flashlights, but instead of lighting up a long corridor, they light up an endless tunnel of space and time. In fact, they are critical to the discovery of the dark universe, helping to reveal the existence of dark matter in 1933 and dark energy in 1998.

Pantheon+ took things to the next level. The scientists behind the analysis focused on more than 1,500 supernovae that, when combined, collectively illuminate about three-quarters of the known universe. Really.

A timeline of the universe.


“With this combined Pantheon+ dataset, we get a precise view of the universe from when the universe was dominated by dark matter to when the universe was dominated by dark energy,” said Dillon Brout, an astronomer at the Harvard-Smithsonian Center for Astrophysics. said in a statement.

“This dataset is a unique opportunity to see dark energy unfold and advance the evolution of the cosmos at the largest scales ever,” Brout said. Said.

This might settle a few scientific debates

Down the road, the Pantheon+ legacy prepares to transcend the dark universe.

As an added bonus, the analytical tool also confirmed that the cosmos is indeed expanding at an accelerating rate. and It offered extremely promising evidence supporting the cornerstone of scientific thinking: the Standard Model of Particle Physics.

This framework pretty much outlines how each known particle behaves independently as well as with each other, and even serves as the basis for many leading theories about what the dark universe really is all about.

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An image of particles in the Standard Model.


“We’re able to place the most precise constraints ever on the dynamics and history of the universe,” said Brout. “We’ve combed through the data and now we can say with more confidence than ever that how the universe has evolved over the ages and that the best theories available for dark energy and dark matter are strong.”

In other words, Pantheon+ may be telling us that we need to complete some alternative theories of dark matter and dark energy. irrelevant to the Standard Model. These theories may not be true.

We also need to talk about my favorite outcome of the Pantheon+ datasets. It might finally help put a long-running, rather heated debate among physicists to rest.

We may finally be on our way to decoding what’s known as the Hubble constant. A kind of.

Basically, we know that the universe is expanding exponentially. We can literally see it happen in real time. But scientists cannot agree on the exact rate at which this expansion occurs. The key to the solution is the Hubble constant, but different ways of calculating this constant seem to give different answers.


Arcs and lines in the Abell 370 galaxy cluster reveal the “gravitational lens,” which is the distortion of light from distant, background galaxies by the cluster’s gravitational field. The lensing effect helps astronomers measure the distribution of dark matter in galaxy clusters.

NASA, ESA and Hubble SM4 ERO Team

After combining the Pantheon+ sample with data from another scientific collaboration, a Harvard press release states that we may now have the most stringent local measurement of the current expansion rate of the universe. (The keyword here is “local”. That’ll come later.)

In summary, the collaboration found the Hubble constant to be 73.4 kilometers per second (45.6 miles) per megaparsec (km/s/Mpc). 1.3% uncertainty.

“In other words, for every megaparsec, or 3.26 million light-years, analysis estimates that in the nearby universe, space itself is expanding at more than 160,000 miles per hour,” the publication explains. This figure, for context, is right in the middle of the 2001 milestone measurement of 72 km/h/Mpc and later reports of 74 km/h/Mpc.

However, it is quite far from another leading metric that recommends a constant of 69.8 km/h/Mpc.

Ok, yes, there is still an inconsistency. And again Pantheon+’s constant is based on “local” measurements.

That’s why the Pantheon+ team emphasizes that “observations from an entirely different era of the universe’s history predict a different story.” So, in a way, having a new opposite Hubble constant, immortality Raising the already fraught debate instead of resolving Hubble tensions? Like I said, it’s complicated.

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A simulation of dark matter filaments in the universe.

Zarija Lukic/Lawrence Berkeley National Laboratory

“We thought it would be possible to find clues in our dataset to find a new solution to these problems, but instead we find that our data excludes many of these options and that the deep differences are as stubborn as ever,” Brout said. Said. .

But at the end of the day, because Pantheon+’s results are so naive, perhaps they can at least explain where the point of contention lies in Hubble’s constant debate.

“Many new theories are starting to point to exotic new physics in the very early universe,” Brout said. Said. “However, such unconfirmed theories must be based on the scientific process, and the Hubble tension remains a major challenge.”

Physics is filled to the brim with complex puzzles, riddles and, to be honest, roadblocks. But I like to imagine these obstacles as motivation to keep the field going and turn minds. This is why Pantheon+ was innovative in the first place.

And with this mechanism, we have certainly advanced, at least in studying the truth about the dark side of our universe. Or, as Brout puts it, “Pantheon+ gives us our best shot yet to limit dark energy, its origins and evolution.”