Astrophysicists are searching every possible corner of the universe for answers to the mysteries that shroud the cosmos, and they are using every technology at their disposal to do so. These efforts have revealed the overall mass and energy densities of the universe, allowing cosmologists to map the universe on a large scale.
It turns out that ordinary matter is only a minor component of the universe. Everything visible to us — you, me, animals, trees, and planets — accounts for less than 5% of the universe. A mysterious substance known as "dark matter" accounts for 20% of the universe. What is the most abundant thing in the universe? An unidentified type of energy that quickly stretches, tears, and expands the fabric of space-time. It's known as "dark energy," and it accounts for more than 70% of the universe.
A new attempt to comprehend dark energy has resulted in the reconstruction of a three-dimensional map of the observable universe. It is the most detailed 3D map created to date. And the outcome is fascinating.
The science and other important information
Kitt Peak National Observatory is located in Arizona's mountainous terrain, where astrophysicists and cosmologists work to observe the night sky. One of its instruments is dedicated to deep space observations in order to collect data for research into the nature, effects, and distribution of dark energy. As previously stated, this is a type of energy unknown to scientists that is responsible for the universe's accelerated expansion.
The Dark Energy Spectroscopic Instrument (DESI) became operational in mid-2021 and has already collected enough spectroscopic data to model an enormously detailed 3D map of the observable universe. For at least another four years, DESI will scan the night sky. It is expected to have mapped more than 35 million galaxies by 2026.
3D map slice based on DESI observations. Credit: D. Schlegel/Berkeley Lab/DESI
Two structure distribution cones can be seen in the 3D model images. This is because we can't see the entire universe because the dense galactic centre obscures the structures behind it. To complete the map, we may have to wait 175 million years — the time it takes the Sun to travel to the opposite side of the galactic disc.
What's the big deal?
Cosmologists still don't understand why dark energy exists, and they don't know the full shape of the universe. Because of our ignorance, we cannot make accurate predictions about the future of the universe. It's possible that it expands indefinitely and all the matter within it disintegrates and cools, resulting in a stage known as the "Big Freeze" by physicists. Another possibility is that the expansion comes to a halt for some reason related to the exotic nature of dark energy, and gravity begins to concentrate matter, resulting in a "Big Crunch": a collapse opposing the Big Bang.
The data provided by DESI will aid cosmologists in understanding how dark energy operates in the expansion dynamics and forecasting the universe's future.
What comes next?
The team notes that the data provided by this instrument will allow them to improve dynamic models of galaxy formation and large-scale structures in the coming years. They also explain that they will be able to map the distribution of dark matter in galactic clusters more precisely.
In this regard, DESI continues to measure the universe's expansion rate and refine the current cosmological model. According to Prof Carlos Frenk of the Institute for Computational Cosmology, DESI data will "help uncover some of the most intimate secrets of the cosmos." "We will also learn more about dark matter and the role it plays in the formation of galaxies like the Milky Way and the evolution of the universe," he told the BBC.
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