The gigantic arc is cracking cosmology

Wherever we point our telescopes, the universe looks pretty much the same, and if we zoom out far enough, the galaxies are evenly distributed. It is a basic assumption upon which our knowledge of the universe is based. So when Alexia Lopez, a British astronomy student, saw a thin line of galaxies running all the way from east to west on an image of the sky, she raised her eyebrows. The universe seemed to be smiling at her.

As a student at the University of Central Lancashire, UK, Alexia Lopez looked for patterns in the distribution of galaxies billions of light years from Earth. When she zoomed out and studied a larger portion of the skin, she went from amazement to pure shock.

You’ve found an absurdly large, nearly symmetrical arc of galaxies spanning 3.3 billion light-years, and it’s one of the largest structures ever discovered in the universe. giant bow It’s about 9.2 billion light-years away, so if we could see it with the naked eye, it would stretch across the sky by 20 full moons side by side.

discovery Wonderful, because such large structures contradict the cosmological principle, which describes the structure of the universe and states that no part of the universe looks different from any other.

In other words, the smiley face is so big that it shouldn’t actually exist. It challenges physicists’ theory of the evolution of the universe. The universe may not be as old as we thought.

The materials must be distributed evenly

For more than a hundred years, astronomers have worked on the assumption that the universe is homogeneous and isotropic. This means that matter is generally evenly distributed and that the universe appears the same, no matter where we look.

It may seem strange for physicists to assume that the universe is a homogeneous mass. Just by looking at ourselves, it is clear that this is not the case.

As human beings, we are denser than the air around us and live in a part of the universe where matter has accumulated in a rocky planet surrounded by emptiness. It, in turn, orbits another highly dense spherical object: the Sun.

The solar system is part of a galaxy, which is one of billions of star clusters in the universe. Therefore, matter does not appear to be actually evenly distributed in the universe.

However, the cosmological principle states that the density in one part of the universe should not be greater than anywhere else. If you only zoom out enough, the matter will be evenly distributed and not clump together.

Physicists have simplified the universe

in our galaxy Milky Way There are between 100 and 400 billion stars, many of which have planets in orbit. The Milky Way is just one of the trillions of galaxies in the visible universe. Galaxies orbit each other in galaxy clusters, which in turn can be grouped together into giant clusters.

The cosmological principle leaves no room for large galaxy clusters, but if matter is evenly distributed, there is a limit to how wide the structures can be. Using advanced mathematics, this limit can be calculated 1.2 billion light yearsWhich corresponds to 11,000 billion billion kilometres. However, the giant bow discovered by Alexia Lopez is three times larger than that.

If the cosmological principle is not consistent, scientists need to rethink the entire cosmological model, which has been based on Einstein’s general theory of relativity since 1915.

The theory of relativity states that gravity can be understood as the curvature of spacetime, which is caused by matter – or in general energy – that is around the universe.

Einstein’s equations are incredibly difficult to understand, but in the 1920s and 1930s physicists Alexander Friedman, George Lemitri, Howard B. Robertson, and Arthur J. Walker were able to discover how the theory of relativity could be used to describe the entire universe and its evolution. .

However, this feat was made possible by the fact that the four physicists chose to regard the universe as a smooth soup of particles. Only by ignoring the fact that matter clumps together can they develop a model of the universe.

The cosmological principle simply made Einstein’s equations easier to work with, but it also seems self-evident that the expansion of the universe should distribute matter relatively evenly.

Since then, astrophysicists have started from this relatively simple model of the universe. The problem, however, is that over time they have discovered many structures that appear to violate the cosmological principle.

3D map reveals large structures

Supercluster galaxies only become visible when large parts of the universe are mapped in three dimensions. The most comprehensive survey of its kind is the Sloan Digital Sky Survey, which is the result of two decades of data collection with a telescope in the US state of New Mexico.

In this massive catalog of millions of galaxies and quasars – the brightest galactic cores – astronomers around the world can dive in. Not least where they found some of the largest structures in the observable universe.

As early as 2003, the survey was able to reveal a “wall” of galaxies 1.37 billion light-years long, the Sloan Great Wall, a series of giant clusters about a billion light-years away.

If Sloan’s Great Wall is unique, the cosmological principle may have escaped detection, but over time a few structures of larger galaxies or quasars have been found, including the smiling Arc, which was also found using data from the Sloan Sky Survey. digital.

Giant structures therefore suggest that the Cosmic Standard Model needs an overhaul, and physicists have many suggestions on how to improve it.

Some attempt to develop a heterogeneous cosmology and consider how the evolution of the universe has been affected by the computation of these structures. Larger structures probably wouldn’t be a problem with such a model.

Others work with the theory that gravity over very long distances acts differently than Einstein described, thus creating an uneven universe.

The third method is dark energy, a hypothetical form of energy in space, which causes the universe to expand faster. Dark energy is an integral part of the cosmological standard model and is described as constant. However, according to some scientists, they may differ in either time and space – or that hypothetical energy is not necessary to describe the universe.

The new cosmology could change the calculations of the expansion of the universe, and thus perhaps also our dating of it. This could mean that the universe was not 13.8 billion years old at all, as the Standard Model states.

At present, however, cosmologists are not ready to write off the cosmological principle. Before they ditch the proven theory, they want to see a more accurate map of the observable universe. It needs to show more details of the larger structures that have already been found and show if there is more out there.

Fortunately, there is hope here, because as early as December 2023, a new and very comprehensive survey of the universe will begin with the help of the newly built large Vera C. Rubin Observatory in Chile. The telescope there will give astronomers significantly more detailed images of the upper half of the sky and they will also be able to see more in the past.

A comprehensive survey will show whether it is still reasonable to consider the universe as a smooth soup, or whether there are lumps in it. If the night sky – in the big picture – isn’t the same no matter what planet we’re on and in what direction we’re looking, it’s time for a new model of the universe.