Scientists used the largest database of supernovae in history to estimate the distance to distant galaxies. Thanks to this, they estimated the amount of dark energy and concluded that it changed over time.
Dark energy
A study that could be described as sensational was recently published in The Astrophysical Journal. After all, it suggests that dark energy is not constant over time, and this affects our entire understanding of the evolution of the Universe.
The fact that our Universe is expanding has been known since the beginning of the 20th century. Einstein’s equation describing the relationship between matter and energy and space contained an element known as the “Lambda.” It was introduced to obtain stable solutions, and for many years it was believed to be equal to zero.
If it were different from it, the expansion of our Universe would proceed with constant acceleration. This was discovered in 1998 thanks to research on Type Ia supernovae in other galaxies. They made it possible to determine the distance to them and, as a result, the speed of dispersion.
Then it was decided that Lambda had a certain static value, for which dark matter was responsible, as most matter exists in this form and does not manifest itself in any other way. However, at that time, the conclusion about the value of Lambda was based on very few supernovae, and no one could say with certainty that the amount of dark matter had remained unchanged over the billions of years since the Big Bang.
New research
And now, more than 25 years have passed since the discovery of dark matter, and during this time scientists have gathered significantly more information about supernova-type explosions in other galaxies. In total, they found 2,087 cases in 24 datasets covering a period of 7 billion years.
Scientists analyzed all these eruptions using a Bayesian Hierarchical Model. The study showed that the value of Lambda, this cosmological constant, did not remain constant throughout this period, and now all this needs to be explained somehow with the help of dark energy.
According to phys.org
