The Biggest Dark Energy Map Could Reveal the Fate of the Universe


A modified telescope in Arizona has produced an interim map, which is already the largest three-dimensional map of the universe ever made – and the instrument is only about a tenth of the way from its five-year mission.

The Dark Energy Spectroscopic Instrument (DESI), a collaboration between Lawrence Berkeley National Laboratory in California and scientists around the world, was installed between 2015 and 2019 on the Mayall Telescope at the Kitt Peak National Observatory in the desert of Sonora, about 50 miles (88 kilometers) west of Tucson, and has been investigating for less than a year.

Its goal is to create an even larger 3D map of the universe, in order to better understand the physics of dark energythe mysterious force that accelerates the expansion of the universe.

Related: Did a Dark Energy Discovery Just Prove Einstein Wrong? Not enough.

“There’s a lot of beauty in there,” said Julien Guy, a Berkeley Lab physicist working on the project. “In the distribution of galaxies on the 3D map, there are huge clusters, filaments and voids.

“They are the largest structures in the universe,” he added. “But in them you find an imprint of the very first universe and the story of its expansion since then.” Researchers hope that understanding the effects of dark energy could help them determine the ultimate fate of the universe.

The DESI team used a giant two-dimensional map of the universe released in January 2021 to prepare the instrument for the three-dimensional survey, which began a few weeks later.

The new 3D map identifies the locations of more than 7.5 million galaxies, far surpassing the previous record of about 930,000 galaxies (opens in a new tab) set by the Sloan Digital Sky Survey in 2008.

In this 3D scan of the universe, Earth is depicted in the lower left, looking at the directions of the constellations Virgo, Serpens, and Hercules from distances greater than 5 billion light-years. Each colored dot represents a galaxy, itself made up of 100 billion to 1,000 billion stars. Gravity has grouped the galaxies into structures called a “cosmic web”, with dense clusters, filaments and voids. (Image credit: D. Schlegel/Berkeley Lab using DESI data)

galaxy investigation

DESI collects spectroscopic images of millions of galaxies spread across about a third of the sky, according to a Berkeley Lab statement (opens in a new tab).

By looking at the color spectrum of each galaxy’s light, scientists can determine how much light “red shifted” – that is, stretched towards the red end of the spectrum by a Doppler effect caused by the expansion of the universe. In general, the greater the redshift of a galaxy, the more it s moves away quickly and the further away it is from observers on Earth.

Our universe has been expanding since its beginnings with the big Bang about 13.8 billion years ago, and it is now much larger – at least 92 billion light years across – only the farthest distances we can see.

Related: From the Big Bang to today: snapshots of our universe through time

Project DESI scientists hope their 3D map of the cosmos will reveal the “depth” of the sky and help them map galaxy clusters and superclusters, the statement said. Because these structures carry echoes of their initial formation as physical ripples in the material of the infant cosmos, researchers hope to use the data to determine the history of the universe’s expansion — and its ultimate fate.

“Our scientific goal is to measure the wave footprint in primordial plasma,” Guy said. “It’s amazing that we can actually detect the effect of these waves billions of years later, and so early in our investigation.”

dark energy

Scientists used to think that the universe was expanding at a constant rate, or that the combined matter and energy in the universe could possibly slow this expansion. But observations of powerful stellar explosions called supernovae at the end of the last century showed that the expansion was actually accelerating, so scientists coined the term “dark energy” to explain this unexpected phenomenon.

Calculations now suggest that dark energy accounts for about 70% of the total energy in the observable universe. The effects of dark energy are now recognized as the “cosmological constant” that Albert Einstein included in his theory of general relativity; Understanding dark energy has become a crucial scientific goal over the past few decades, according to Smithsonian Magazine (opens in a new tab).

It appears that more dark energy is being created as the universe expands, which is accelerating the expansion of the universe, according to the statement.

Ultimately, the effects of dark energy will determine the fate of the universe – whether it will forever expand, tear apart, or collapse again in some sort of inverted Big Bang.

DESI now lists the redshifts of about 2.5 million galaxies each month. The team plans to complete the 3D survey map in 2026, by which time the telescope will have observed around 35 million galaxies.

DESI scientists are presenting some early astrophysical results from the instrument this week in a webinar hosted by Berkeley Lab, called CosmoPalooza.

Originally posted on Live Science.

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