Researchers from the University of Pennsylvania and the Laboratory of Lawrence Berkeley have made a fascinating discovery about the evolution of the Universe. After over 13.8 billion years, they have found that the Universe is becoming “more confusing” as its distribution of matter is less dense than previously thought. This groundbreaking research, published in the Journal of Cosmology and Astroparticle Physics, provides scientists with new insights into the evolution of the cosmos.
Under the leadership of Joshua Kim and Matthew Madavacheril, the team of scientists utilized data from two major projects: the final release of data from the ACT (ATACAMA) telescope and the first year of observations from the Desi (Dark Energy Spectroscopic Instrument) tool. By combining these datasets, researchers were able to compare ancient and modern views of the universe, offering a multidimensional perspective on the history of cosmic matter.
The ACT telescope, covering 23% of the sky, captures data on relict radiation – essentially the “first photograph” of the universe taken when it was only 380 thousand years old. These observations reveal how light has been distorted by gravitational lenses, a phenomenon first theorized by Einstein.
On the other hand, the Desi tool provides three-dimensional maps of the Universe, examining the distribution of millions of galaxies, particularly bright red galaxies known as LRGs (LRG). These galaxies serve as significant markers to trace the evolution of matter over billions of years.
By combining the data from ACT and Desi, researchers were able to directly compare the early and later stages of universe structure formation. They observed a slight discrepancy: the density of matter in later stages was lower than anticipated. This discrepancy is quantified by the σ8 (SIGMA 8) metric, which measures the amplitude of density fluctuations. Lower σ8 values could suggest a deceleration in the growth of cosmic structures.
While this discrepancy is not yet sufficient to confirm the presence of new physics, it may indicate the role of dark energy in structure formation. Moving forward, the team plans to utilize new tools like the Simons Observatory to further investigate and clarify these findings.