The largest galaxy survey ever conducted suggests that our universe is not as massive as expected.The lack of lumps means that Einstein’s General theory of relativityUsed by scientists to understand how the structure of our universe has evolved over 13 billion years.
“If this imbalance was true, Einstein might have been wrong,” said Neil Jeffrey, one of the co-leaders of The Dark Energy Survey (DES) and a cosmologist at the Ecole Normale Superiore in Paris. Said. Told BBC News
The DES team edited a catalog of hundreds of millions of galaxies and used small distortions in the shape of those galaxies to measure cosmic vital statistics. Almost all of those measurements confirmed the predominance. big Bang Model Cosmology, All matter in the universe was incredibly hot and expanded from an incredibly small point.
However, the massiness of the substance, which is one of those measurements, was slightly off. If the universe is smoother than expected, it means that our understanding of how the structure of the universe evolves based on Einstein’s general theory of relativity is wrong.
Some news headlines have already declared that Einstein is wrong and physicists need to modify the model, but the reality is more subtle. This is because the discrepancy is not yet a statistical slam dunk.
Largest survey ever
More than 400 scientists from 25 institutions in seven countries are working on DES. The team used the 4-meter (13.1 ft) Victor M Blanco telescope at the Cerro Trollo Inter-American Observatory in Chile to stare at one-eighth of the entire night sky during the 758-day observation period.
The observation project started in 2013 and ended in 2019. However, the observation was an easy part. The DES collaboration took two years to release the latest results, taking into account only the data from the first three years of observations.
And that’s great.
Described in the avalanche of 29 scientific treatises, this release contains detailed observations of 226 million galaxies, making it the largest and most detailed galaxy survey in history.
This vast catalog is less than a tenth of all observable galaxies in the universe, but this is the beginning.
How to measure the universe
DES used a treasure trove of galaxies to study two main features of the universe. One is called the Cosmic Web. It turns out that galaxies are not randomly scattered in the universe, but are organized in the largest pattern found in nature. On a very large scale, astronomers find huge chunks of galaxies called clusters, long filaments of galaxies, wide walls, and vast, empty space.
The Cosmic Web is a dynamic object that has evolved into its current state over billions of years. Astrophysicists believe that long ago, matter in the universe was much more evenly distributed. By studying the evolution of the universe’s web, DES scientists can understand what the universe is made of and how it works. If you change the ingredients to your favorite cake recipe, the evolution of the universe will be determined by the contents of the universe, just as the way you get out of the oven will change.
DES also uses what is called the weak gravitational lens effect.From Einstein’s general theory of relativity, gravity You can bend the path of light. The most famous example of this comes from the cluster of galaxies. Their incredible mass can greatly distort the light from the background galaxies, so they appear to the observer to be very stretched and elongated.
DES employs a more subtle version of this lens effect. It looks for small changes in galaxy shape due to light from galaxies passing through the universe for billions of light years. By comparing the shapes of these galaxies with the shapes of galaxies known in nearby space surveys, DES astronomers can map the distribution of material in space.
Something is out of place
The DES collaborative study compared the results with the results of other major studies, such as the Cosmic Microwave Background Planck study and the Big Bang echo revealed in the faint glow of radiation in space. Their results are almost in line with existing observations and general cosmology.We live in an expanding universe of about 13.7 billion years old, and its mass energy is composed of about one-third of matter (most of it). Dark matter),The rest Dark energy..
But one measurement stood out. It is a parameter called S8 that characterizes the amount of cosmic mass. The higher the S8 value, the tighter the substance will aggregate. The new DES results support the S8 value of 0.776, while the old Planck results show a slightly higher value of 0.832.
Planck results are from early universe measurements, and DES results are from later universes. These two numbers should match, and our understanding of how giant structures grow and evolve over space time, if they are actually different, is Einstein’s general relativity. It may be wrong because it is based on a theoretical understanding of gravity. No one expected this contradiction to be found, so astrophysicists have not investigated exactly what part of the theory of relativity is flawed.
The headlines that welcome the results of DES show that there is a major rift in the foundations of modern cosmology. “I spent my life working on this theory. [of structure formation] Carlos Frenk, a cosmologist at Durham University in the United Kingdom who has nothing to do with DES, told BBC News, “But my brain says the measurements were correct. We need to look at new physics possibilities. . “
But what these headlines (and articles) don’t mention is uncertainty. All measurements come with uncertainty — scientists are not very accurate given the amount of data available. DES and Planck results generally overlap with each other when statistical uncertainty is involved. Not so many. So while the difference is worth digging deeper, it’s not enough to sound the alarm. In statistical terms, the two measurements are off by only 2.3 standard deviations. That is, there is no real difference in the value of S8, and after 100 observations, it will be the same (or higher). ) 98 times difference. This is far from the five standard deviations normally required to signal new discoveries.
Let’s take a look at what the data for three more years will bring.
Initially published in Live Science.
Did the discovery of dark energy prove that Einstein was wrong? Not quite.
Source link Did the discovery of dark energy prove that Einstein was wrong? Not quite.