The latest attempt to rattle the foundations of the universe appeared as a bunch of dots pulled upward. It would take 20 full moons to hide the arcs of distant galaxies presented by Alexia Lopez at the American Astronomical Society's meeting in June. The structure is an estimated 3.3 billion light-years of space.
Lopez, an astronomer at the University of Central Lancashire who identified the galaxy chain, said it was hard to explain with our current beliefs.
The idea that the universe has no features clashed with Lopez's "Giant Arc" If you look at the picture from a different perspective, you should see roughly the same number of galaxies.
This assumption has allowed researchers to draw conclusions about the universe based on what we see from our corner of it.
Ruth Durrer, a cosmologist at the University of Geneva, said that if that turns out to be incorrect, we have to redo many of our measurements.
The cosmological principle has become a target as a load-bearing strut. Lopez and her colleagues are puzzled by the striking conglomerations. Some maverick cosmologists are not sure if theorists conjured phantasms to patch up an overly simplistic theory of the universe, because they think most of the stuff in the universe hides from our instruments.
Everyone agrees that the principle is worth looking at. Each new claim of a too-big structure has failed to make a difference. We are trying to poke as many holes as we can, while being very skeptical of someone else saying they have poked a hole.
From Einstein to Copernicus.
The idea that Earth isn't the fixed center of creation came from the Copernican principle. His insight that Earth is in the same position as the sun set off a series of shifts in perspective. The sun is a normal star according to theAstronomers in the 1800s. In the next century, they spotted many more stars.
Andrew Howell is a cosmologist at Las Cumbres Observatory and the University of California, Santa Barbara. The universe keeps telling us.
Earth is not special, but nothing else is. What is now known as the cosmological principle was solidified by surveys over the past century. Powerful telescopes peered deeper into the darkness to see more distant galaxies. This shows that the universe is smooth and uniform. Think of the expanding universe as a fruitcake with galaxies evenly spread like fruit pieces, each one flying away from its neighbors as the batter between them expands.
Telescopes pointed in different directions have seen similar scenes. The universe is "isotropic", meaning that it is evenly distributed along every line of sight.
The isotropy and homogeneity of the universe make it easy to analyze.
Theorists use a standard theoretical model based on Albert Einstein's theory of gravity to reconstruct the past and predict the future. The bendy fabric of the universe is described in Einstein's theory. Einstein uses a system of equations that is too complicated to solve.
The universe is acting as a smooth and symmetric fluid because of the principle of the cosmological principle. The principle of the cosmological principle is that the universe should expand in the same way along all three axes and that parts of the equations should be deleted. The Friedmann equations, derived from Einstein's, can be used to predict the expansion of the universe. It is similar to computing the volume of the Earth, where you can fret over every mountain and ravine or assume the planet is a sphere and call it a day.
As the universe is mapped more precisely, a few researchers are wondering if the field has pushed the principle too far. Earth is not a sphere because it bulges at the equator. Large structures or asymmetrical features could undermine conclusions about the universe's age, behavior and composition.
The Claude Bernard University of Lyon 1 in France has a cosmologist who believes that it is time to move beyond Friedmann's universe. He said it was strange that it was still alive.
Galaxies are everywhere.
homogeneity is the first pillar of the principle.
On the human scale, the universe is not homogeneity. One light-year from here will ruin a person's day. If you drop the Hubble Space Telescope halfway across the universe, it will return familiar looking images. The air in a balloon is treated like the air in the universe. Molecules mingle in complicated ways up close. A bland gas expands with bulk properties, like pressure and temperature.
The same amount of matter can be found in any patch of space larger than hundreds of millions of light-years across. The Giant Arc, which spans billions of light years, is as unexpected as a thick clot of air in a balloon.
The first of these structures was identified in 2013 and it was a group of brilliant galaxy cores known as quasars.
Few people were convinced. If randomness alone could create the illusion of megastructures, was that possible? He created universes that were chaotic. He set a cluster-hunting program loose on the smooth simulations and it picked out patterns as large as the quasar group by chance. There would be groupings of galaxies that were grander still in a Simulated standard-model universe. The quasar group, the Giant Arc and others of their ilk were suggested by the work of Nadathur. The standard model doesn't say the probability is zero at any scale.
The discovery that matter has lumpiness as you look at larger scales would be a more convincing observation of inhomogeneity. The studies have consistently shown that the universe gets better as you zoom out.
According to Durrer and others, seemingly impossible structures can be explained by statistics. She said that if you make a lot of observations, you will have some that are not very probable. I am not very worried about that.
The universe is directionless.
Even if the universe is not all that different, it could still be a direction for something special. Great streams of matter could flow in that direction. Some scientists think this might be happening.
Evidence against any sort of flow comes from the Big bang. Astronomers have determined that the Cosmic Microwave Background (CMB) has an average temperature of 2.725 degrees above absolute zero in every direction.
Researchers correct for a slight discrepancy in the temperature between the opposite direction and the direction of the constellation.
