Thursday, June 23, 2022

Light distortion can tell the nature of dark energy

Cosmology is an area associated with astronomy that studies the origin, evolution and end of the universe. But because these are very broad scales, the task becomes extremely complicated. One of the main mysteries of the universe is dark energy. We don't know what it is, but we do know that it somehow accelerates the expansion of the universe.

 Basically, the universe started as a single dot. But in a few moments he already reached colossal sizes. Since then, the universe has expanded. Although it was already a debate in science, Edwin Hubble rose to prominence by suggesting the expansion of the universe. Yes, he's the same guy who gave the mighty Hubble Space Telescope its name. Before that, even Einstein suggested that the universe expanded, as Relativity in a way showed. But then he went back, and added a 'cosmological constant' to keep the universe static in his Theory of Relativity - a real "gambiarra". 

But today we know that Relativity is correct and we also know that the universe expands. Imagine a bladder filling. It doesn't stretch in just one piece, right? In fact, its entire surface expands. With a pen, make a few dots on a balloon and fill it. The points will distance. This, then, is how we know that the universe expands. All groups of galaxies are moving away from each other.

 Dark energy and the quintessence

Now, scientists have figured out how to use light to our advantage. They say, in a new study published in the journal Physical Review Letters, that the behavior of "ancestral light" can give us clues. This light they refer to is part of the Cosmic Microwave Background Radiation (CMB). This light is a holdover from the early universe, when everything was still extremely hot and dense, a few hundred thousand years after the Big Bang.

They suggest that quintessence would cause this light twist. Quintessence is another term to refer to something hypothetical and unknown, but which causes a phenomenon that we observe. This clashes with some current theories, so something will need an overhaul – the current theories or the new hypothesis. But scientists point out that this is a temporary thing. But the idea of ​​quintessence also matches some theories in the field. For example, one of the possible endings for the universe is the Big Crunch. In it, the universe would shrink rapidly, until it became that speck again.

 There are even those who suggest that this occurs continuously – an expansion followed by a contraction, in an infinite cycle.

New perspectives

Although they cause similar phenomena, dark energy and quintessence are different things. Dark energy is not a very good name, as there is no energy. There is nothing palpable, like electricity and light. Dark energy is, then, a property of spacetime. In this case, it is something uniform and that can be explained through a cosmological constant.

But others suggest that dark matter is, far from true, the quintessence. Quintessence is like the ancient idea of ​​Ether – a substance that permeates the entire cosmos. But functions change. The Ether did nothing, it just existed. Quintessence, on the other hand, would help in the expansion of the universe, according to the line of thought.

The pair then analyzed data from the European Space Agency's Planck mission, which collected data up to 2013 in order to map the CMB. In the data, they found characteristics that point to a possible quintessence. However, although published in a relevant journal, their work is of low statistical significance and goes against much of what we know. In addition, other groups did not find the signatures. If a quintessence does exist, the entire cosmology will need an overhaul, as even calculations of the age of the universe (13.8 billion years) would be wrong. 

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