Based on data collected in one of the most extensive catalogs of cosmic objects that exist (called SDSS), research carried out at the University of Central Lancashire has identified a huge structure, not directly observable and made up of millions of galaxies. , which tests one of the fundamental principles on which our knowledge of the universe is based, according to which the cosmos, on a large scale, is homogeneous in terms of the distribution of matter.
The Great Ring, the name that has been used to refer to this structure, has a size of 1.3 billion light years and is located 9.2 billion light years away from Earth. Despite being so far away, if it were possible to see it with the naked eye in the night sky, it would occupy an area equivalent to 15 full moons.
It is not the first time that astronomers detect similar structures with such large dimensions. Furthermore, it so happens that the new discovery was made by Alexia Lopez, a doctoral student who had previously also found another even larger structure, called the Giant Arch.
Our solar system is heterogeneous, with planets of different sizes and compositions. Likewise, the place that the Sun occupies within the Milky Way is very different from the innermost region of the galaxy where there is a greater density of stars. And the closest galaxies, which together with ours form the so-called Local Group, are also very different from each other.
But as the perspective broadens, these differences between regions progressively dilute, and the universe, on a large scale, appears very homogeneous. In such a way that, when the cosmos is observed at great distances, the distribution of the enormous galaxy clusters (groups that can contain millions of galaxies) and the large empty spaces that exist between them appears similar.
All of this has led to what is known as the Cosmological Principle, which establishes that, on a large scale, there are no privileged regions or directions in the universe, and that the distribution of matter is highly uniform. A consequence of the model is that the fragment of the universe that we observe from our position should also be homogeneous.
The detection of gigantic structures, such as the Great Ring or the Giant Arch (and a few others that are known) seems to challenge the Cosmological Principle, or at least it could require, for it to remain valid, to contemplate the universe on an even larger scale.
According to Alexia Lopez, “cosmologists calculate that the maximum theoretical size for structures is 1.2 billion light years, and yet these two are much larger (the Giant Arch is 3 times larger, and the circumference of the Great Ring is comparable to the length of the Giant Arch). And she adds that the fact that the two structures are relatively close to each other is “extraordinarily fascinating.”
Although the Great Ring appears to have a circular shape in the sky, detailed investigation shows that it would be more of a spiral that is located in a way that shows us its front part. For its part, the Giant Arch, with its 3.3 billion light years in size, has an almost symmetrical curved shape.
The location in the sky of these two large structures is relatively close, since they appear separated by only 12 degrees of vision (this distance is equivalent to 24 full moons in the sky). In addition, they are located at approximately the same distance from Earth, about 9,200 light years. That is, they existed when the universe was half its current age and, therefore, due to the expansion of space, at those times their separation must have been even smaller. Therefore, for Alexia Lopez, the identification of two structures so extraordinarily large and so close to each other could suggest that they may be part of a larger configuration.
The formation of such immense structures could be due to the existence of hypothetical cosmic strings, entities that, according to some cosmologists, could have formed in the first moments of the Big Bang.
Of extremely thin dimensions (much smaller than that of an atom) but with enormous lengths, these supposed threads would have concentrated a gigantic mass, at the beginning of the universe, and could have acted as seeds around which the great structures of the cosmos were created ( one of the proponents of the existence of these cosmic strings is the 2019 Nobel Prize in Physics, Jim Peebles).
Lopez and his team suggest that another option to explain the origin of these structures would be to resort to new models of the evolution of the universe, such as the so-called conformal cyclic cosmology. A hypothesis defended, among others, by Roger Penrose (Nobel Prize in Physics in 2020) and which establishes that the universe is in an iterative development, with births that occur one after another and in infinite cycles.
The discovery of these structures, not directly observable, has been made through the analysis of the light of quasars, very distant galaxies (and, therefore, ancient) that we can observe thanks to the large amount of energy emitted by the matter that falls towards us. the supermassive black holes that reside within it.
The light from quasars, to reach our instruments, has had to travel great distances and cross through regions of space in which concentrations of galaxies are found that are too weak to be observed.
Therefore, throughout its journey the radiation is affected by the interaction with the atoms of these concentrations of matter. The traces that the interactions have generated in the light can be recognized by studying its spectrum (that is, the decomposition of light with a prism), and this allows us to deduce the presence of galaxies existing between us and the distant quasars.
