Science 4 min read

DESI Will Map 11 Billion Years of The Universe Expansion History

To understand the Universe expansion at present, astronomers will be mapping millions of galaxies to reconstruct billions of years of cosmic history.

Image courtesy of Shutterstuck

Image courtesy of Shutterstuck

Although astronomers gained substantial knowledge about the universe in the last decades, they still don’t know a lot about its origin and how it came to be the way it is today.

They know that the universe is expanding but can’t come to conclusive evidence as to how fast is this universe expansion. It seems that the cosmos is expanding at a much faster rate than previously thought.

A new highly anticipated technique to measure the Hubble Constant, or value for the expansion rate based on dying red giant stars, has failed to settle the debate.

There’s the role of the hypothesized dark energy in the acceleration of the universe expansion, and a new mission is set out to bring some answers.

Mapping Past Universe Expansion

Scientists have no clue what dark energy really is. It could be a new form of exotic matter or another fundamental force of the universe. It could also be something entirely new, which is permeating all of the cosmos.

Astronomers don’t know the nature of dark energy or its source. But, they have evidence pointing to this mysterious energy that’s strong enough to shift the whole universe and cause it to expand at an accelerating rate.

Now, a telescope retrofitted with thousands of small robotic arms will be used to elucidate the nature of dark energy — the enigmatic force that is pushing the universe to accelerate at an ever-faster pace.

The Dark Energy Spectroscopic Instrument (DESI) is the first cartographic experiment aiming to map the past universe expansion and investigate the role of dark energy.

The DESI survey, scheduled to start as early as January 2020, will use an optical telescope, the Mayall 4-meter Telescope at Kitt Peak National Observatory in Arizona. For five years, the mission will capture optical spectra from 35 million galaxies and quasars to reconstruct the history of cosmic expansion.

Read More: Hubble Measurement Confirms Discrepancy in Universe’s Expansion Rate

This spectrographic survey of the sky would allow scientists to answer “the first and most basic question about dark energy: is it a uniform force across space and time, or has its strength evolved over eons?”

The large 3D map of the Universe that DESI would produce will not only be used to study dark energy but also to make some serendipitous discoveries along the way.

Berkeley Lab’s Michael Levi, DESI’s Director, says:

“DESI is principally funded by the U.S. Department of Energy to explore some of the biggest questions in astrophysics. We’re working with more than 70 collaborating institutions from around the world and everyone is very excited to learn what DESI can teach us and what discoveries lie ahead.”

Astronomers know for a fact that the expansion of the universe is speeding up in time for no apparent physical reasons. But now, they have DESI’s sophisticated instrument to close in on dark energy they suspect.

Due to the number of galaxies it will chart, DESI would surpass previous surveys. And that’s thanks to its unique built and design.

Instead of cumbersome metal plates, DESI uses 5,000 tiny robotic arms that will allow the researchers to observe one part of the sky and quickly move on to the other. This would speed up the process of capturing each galaxy’s light spectra and measuring the redshift.

While it is the first, DESI is not the only effort aiming at studying the past expansion of the universe. Other similar experiments set to start in the 2020s include NASA’s SEPHEREx Mission.

Read More: NASA’s SPHEREx Mission Plans to Survey the Entire Universe

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Zayan Guedim

Trilingual poet, investigative journalist, and novelist. Zed loves tackling the big existential questions and all-things quantum.

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