So far it has been widely acknowledged that the universe is expanding very fast and it is pulled apart by dark energy. However a study conducted at the University of Arizona proves that the Universe’s expansion is not as accelerated as it is believed. The paper was published in the Astrophysical Journal.
In the 19902 cosmologists drew the conclusion that the Universe is expanding at a fast pace by analyzing a special type of supernova. This triggered such a fast expansion that it seemed to be generated by a sort of unseen force.
Researchers at the University of Arizona discovered that certain supernovas are more varied than it was believed in the past. This has an impact on many cosmological matters, such as the speed at which the Universe has been expanding ever since the Big Bang.
According to Peter A. Milne, astronomer of the University of Arizona, the differences among supernovas are not random.
“We found that the differences are not random, but lead to separating Ia supernovae into two groups, where the group that is in the minority near us are in the majority at large distances – and thus when the universe was younger.”
He also added that there are various populations which have not been acknowledged. Things are not as it was assumed before. As you go from near to fart the type of supernovas in fact does not stay the same, but is more diverse.
Scientists used Hubble Telescope and the NASA Swift spacecraft to examine the different degrees of brightness in the supernovas. Milne together with Ryan J. Foley (University of Illinois at Urbana-Champaign), Gautham Narayan (National Optical Astronomy Observatory) and Peter J. Brown (Texas A&M University) examined samples of Ia supernovas using ultraviolet and visible light.
Milne explained that so far it was considered that the supernovas which are fainter must be farther away. This led astronomers to believe that the Universe is expanding at a faster rate than it did in the past. He continued by saying the idea that lies behind this reasoning is the one according to which type Ia supernovas have the same brightness and when they explode they are quite similar. People used the same reasoning for the far side of the Universe too.
Thanks to Swift data the scientists managed to find out that there are two types of Ia supernovas. Afterwards they examine other data sets to see if the situation was the same. Milne remarked that the supernovas population changes in time. However the difference is not perceptible in optical light, but only using ultraviolet. Nobody saw this before and all the supernovas were considered the same. However the findings prove that the nearby supernova samples are visibly redder than the faraway supernovas.
Image Source: Daily Galaxy