There may be a slowdown in the universe’s rapid expansion.


PARIS: The universe is currently growing faster than before, but early findings from the most accurate assessment of its history to date indicate that it may have slowed down recently in comparison to a few billion years ago.

Even while the first results are far from conclusive, if they are accurate, it would add to the enigma surrounding dark energy and probably indicate that there is a significant gap in our knowledge of the universe.

The Dark Energy Spectroscopic Instrument (DESI), located atop a telescope at the Kitt Peak National Observatory in the US state of Arizona, detected these signals indicating the varying speeds of our universe.

Using light that extends up to 11 billion years into the past of the cosmos, scientists have been able to map six million galaxies and quasars.

The 5,000 fiber-optic robots on the device can each observe a galaxy for 20 minutes, enabling astronomers to create what they refer to as the biggest 3D map of the universe ever created.

Arnaud de Mattia, a co-leader of the DESI data interpretation team, told AFP, “We measured the position of the galaxies in space but also in time, because the further away they are, the more we go back in time to a younger and younger universe.”

DESI has created a map of six million galaxies and quasars using light that extends up to 11 billion years into the past of the universe, just one year into its five-year survey.

The findings were presented on Thursday at conferences in the US and Switzerland, preceding the publication of a number of scholarly articles in the Journal of Cosmology and Astroparticle Physics.

DESI’s goal is to provide insight into dark energy, a hypothetical substance that is estimated to account for 70% of the cosmos.

Just 5% of the cosmos is made up of conventional matter, which includes everything you can see. The remaining 25% is made up of the equally enigmatic dark matter.

A constant that isn’t constant?
Scientists have known for more than a century that 13.8 billion years ago, following the Big Bang, the universe began to expand.

However, astronomers were surprised to learn in the late 1990s that it had been expanding at an ever-increasing rate.

This was unexpected since it was previously believed that the cosmos was slowing down due to the gravity of matter, both normal and dark.

However, it was evident that something was causing the universe to expand at ever-increasing rates, and this force was given the moniker “dark energy.”

More recently, it was found that at six billion years after the Big Bang, the cosmos began to accelerate substantially.

According to the main universe model known as the Lambda CDM, dark energy undoubtedly appears to be winning the tug of war against matter.

The universe’s accelerating expansion is referred to in this paradigm as the “cosmological constant,” and it is intimately associated with dark energy.

Early findings from the device are, according to DESI director Michael Levi, “basic agreement with our best model of the universe.”

Levi stated in a statement, “But we’re also seeing some potentially interesting differences which could indicate that dark energy is evolving with time.”

Put differently, De Mattia stated that the evidence “seems to show that the cosmological constant Lambda is not really a constant,” as dark energy would be exhibiting “dynamic” and fluctuating behavior.

aged and sluggish
This may indicate that the universe’s expansion rate has been “slowing down in recent times,” according to DESI researcher Christophe Yeche, after accelerating six billion years after the Big Bang.

Further information from DESI and other equipment, like the space telescope Euclid, would be necessary to confirm whether dark energy does, in fact, vary over time.

However, if it turns out to be true, our conception of the cosmos will probably need to adjust to account for this peculiar behavior.

One possible substitute for the cosmological constant would be a field connected to an unidentified particle.

According to De Mattia, it might even call for revising Einstein’s theory of relativity’s equations “so that they behave slightly differently on the scale of large structures.” But we haven’t arrived yet.

De Mattia emphasized that there are several instances in the annals of science when “deviations of this type have been observed then resolved over time.”

After all, despite over a century of scientific tinkering and probing, Einstein’s theory of relativity is still as solid as ever.


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