The Dark Energy Survey has published results from 5 years of observations and found an interesting result. 
Roberta Duarte meteorized Brazil 01/22/2024 12:00 6 mins
An ambitious project to better understand dark energy has been launched with several countries, including Brazil. In this project, The idea was to map the distribution of galaxies and observe phenomena such as supernovae over years. The observations took place from 2013 to 2019. The collaboration has been analyzing the data since 2020 to understand how the universe is expanding and how fast that expansion is.
The cosmological constant, which is directly related to this expansion rate, is a sensitive point in astronomy. This is because the value seemed to vary depending on the instrument being observed. The investigation should put an end to this discussion.
A new article from the collaboration was recently published. In this work, they analyzed around 1,500 Type Ia supernovae recorded during the five-year observation period. With this data They concluded that dark energy may be more complicated than we thought.
Dark energy
It is estimated that 70% of the universe consists of so-called dark energy. Dark energy would be responsible for accelerating the expansion of the universe. It would have an effect opposite to the attractive force of gravity; Dark energy would have a repulsive effect and would cause objects in the universe to move away.
Dark energy has nothing to do with dark matter. Dark energy is associated with the expansion of the universe, dark matter is associated with gravity on smaller scales.
To date, we do not know what 70% of the universe is made of, if only dark energy is taken into account. When dark matter is considered, this value increases to 95%. This increases astronomers' interest in the question: what does the universe in which we live consist of?
How do you calculate the expansion rate of the universe?
At the beginning of the 20th century, thanks to the work of Edwin Hubble, we knew that the universe was expanding. But it wasn't until the end of the last century that a shocking discovery changed our view of the cosmos: The universe is expanding at an accelerated rate. Since there is an acceleration, we assume that an interaction is the cause.
The first measurements used LA-type supernovae. These supernovae occur when white dwarfs explode. What's unique about this type of supernova is that it is virtually the same no matter where the star is or how it exploded. In other words, The luminosity emitted by a Type Ia supernova is well known. Thus, Type Ia supernovae serve as cosmic candles.
Since we know exactly their brightness and their properties, We can compare the effect that the expansion of the universe has depending on the distance of the supernova from us. It is even possible to quantify how far the universe extends from this point to us.
When Einstein thought he was wrong
With the introduction of his equations of general relativity, Albert Einstein introduced a tool for understanding the universe on a large scale. In his original equations Einstein added a term he called the cosmological constant. He then assumed that the constant was an error and rejected it.
When observations of LA-type supernovae showed that the universe was expanding faster, The cosmological constant was necessary to reconcile the theory with the observations. Even when Einstein himself admitted that he was wrong about a concept, he was later proven to be right.
Cosmological constant
The cosmological constant is a parameter related to the expansion rate and dark energy. In reality, This constant defines the vacuum energy and is assumed to have a value of -1.
This value can give us Predictions about dark energy and even how the universe would end. Different proposals for the end of the universe have been created depending on their value.
The most common constant is -1 is that the universe would end in thermal death. Other suggested values would indicate a Great Tear or a Great Freeze.
What does the dark energy survey find?
After 5 years of observation and about 4 years of analysis, the Dark Energy Investigation Collaboration has published the results. While the density of dark matter corresponded to the expected value, The collaboration revealed that the cosmological constant had a value of -0.80. This value is the best result in years of observation and the range is well defined.
This could indicate that we are either measuring something that is not necessarily the cosmological constant, Or we need a new explanation for dark matter that is more complex than we thought.