The largest survey of galaxies ever shows that our universe is not as lumpy as it should be. That lack of clumsiness could mean there was a discrepancy with Einstein’s. general relativityIt is used by scientists to understand how the structure of our universe has evolved over 13 billion years.
Niall Jeffrey, one of the co-leaders of the Dark Energy Survey (DES) and cosmologist at the École Normale Supérieure in Paris, said: Maybe Einstein was wrong.” told BBC News
The DES team has compiled a list of hundreds of millions of galaxies. and use a small distortion in the shape of those galaxies to measure important statistics of the universe Almost all measurements confirmed its existence. big bang version of cosmologywhere all the matter of the universe expands from a small point unbelievably hot
Related: From the Big Bang to the present: An overview of our universe through time.
But one of those measurements ̵1; the ambiguity of matter – was slightly reduced if the universe was smoother than thought. That means our understanding of the evolution of structures in the universe. which, based on Einstein’s theory of general relativity, would be wrong.
While some headlines declared Einstein wrong. And physicists need to modify their models. That’s because the discrepancy is not a statistical slam dunk.
The biggest survey ever
More than 400 scientists from 25 institutions in seven countries work on DES, one of the largest astronomical collaborations in history. The team used the 4-meter (13.1-foot) Victor M Blanco telescope at the Cerro Tololo Inter-American Observatory. in Chile to gaze at one-eighth of the total night sky over the course of 758 nights of observation.
The Observation Program started in 2013 and ended in 2019, but the observations are the easy part. The DES collaboration took two years to release the latest results. which looked at data from only the first three years of observation.
and it’s amazing
such release Described in 29 scientific papers, detailed observations of 226 million galaxies are available. This makes it the largest and most detailed survey of galaxies in history.
This enormous catalog still represents less than one tenth of the total galaxies in the observable universe. but a starting point
measurement of the universe
DES uses the treasure trove of galaxies to study two key aspects of our universe. One is called the cosmic web. It turns out that galaxies are not randomly scattered in the universe. Instead, it is considered to be the largest form found in nature. on the largest scale Astronomers have found giant galaxy clusters called clusters. Long filaments of galaxies, wide walls, and empty cosmic voids.
The cosmic web is a dynamic object and has evolved to its present state over billions of years. Astrophysicists thought long ago The matter in the universe has a much more uniform distribution. from studying the evolution of web cosmic DES scientists can understand how the universe was formed and how it behaves. That’s because the content of the universe determines evolution. Just like turning an ingredient into your favorite cake recipe will change the way it comes out of the oven.
DES also uses what is known as a weak gravitational lens. We know from Einstein’s theory of general relativity that objects gravity able to bend the light The most famous example of this comes from galaxy clusters. Their incredible mass can distort the light from the background galaxies so much that they appear to be extremely stretched and stretched to the observer.
Related: 8 Ways You See Einstein’s Theory of Relativity in Real Life
DES uses a much more detailed version of the lens effect. It looks for small changes in the shape of galaxies as the light radiates from them through billions of light-years of space. By comparing the shape of those galaxies to what we know the galaxy looks like from observations of the nearby universe. DES astronomers were able to map the distribution of matter in the universe.
Something is off
The DES collaboration has compared their results to other important surveys, such as Planck’s survey of the cosmic microwave background. The Big Bang’s echoes were revealed with radiation that spread throughout the universe. Their results are almost perfect with existing observations and cosmological theories: we live in an expanding universe about 13.7 billion years old, where mass energy comprises about a third of matter. (most of which are dark matter), the rest is made of dark energy.
But one measure stood out: a parameter called S8, which characterizes the amount of clumsiness in the universe. The older Planck’s has a slightly higher value, 0.832.
Planck’s results come from early measurements of the universe. Whereas the results of DES come from the latter part of the universe. These two numbers should agree. and if they are really different Our understanding of gigantic structures that grow and develop during cosmic time. This, based on our understanding of gravity through Einstein’s theory of general relativity, could be wrong, since no one expected this discrepancy. So astrophysicists have not explored exactly which parts of the theory of relativity might be flawed.
The headlines hailed the results of DES as a major crack in the foundations of our modern cosmological theory. “I’ve spent my whole life working on this theory. [of structure formation] And my heart tells me I don’t want to see it break,” Carlos Frenk, a cosmologist at Durham University in England, who is not affiliated with DES, told BBC News. “But my brain tells me the measurements are correct. And we have to look at the possibilities of new physics.”
But what those headlines (and articles) neglect to mention is uncertainty. Every measurement is uncertain – scientists can be very accurate considering the amount of data available. When the statistical uncertainty is included, the results of DES and Planck tend to overlap not much — so the differences are worth digging deeper — but not enough to set the alarm. in the language of statistics Both measurements were off by just 2.3 standard deviations. This means that if there is no real difference between the values of S8 and the 100 iterations of observations, those values will be equal. The difference between the two (or larger) 98 times is very short of the normal 5 standard deviations required to announce a new discovery.
Let’s see what the next three years of data look like.
Originally published on Live Science.