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NotSanguine [soylentnews.org] writes:

The University of Michigan issued a press release [umich.edu] concerning new research on the growth (or lack thereof) of large-scale structures in the universe.

From the press release [umich.edu]:

As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.

But University of Michigan researchers have discovered that the rate at which these large structures grow is slower than predicted by Einstein’s Theory of General Relativity.

They also showed that as dark energy accelerates the universe’s global expansion, the suppression of the cosmic structure growth that the researchers see in their data is even more prominent than what the theory predicts. Their results are published in Physical Review Letters.

Galaxies are threaded throughout our universe like a giant cosmic spider web. Their distribution is not random. Instead, they tend to cluster together. In fact, the whole cosmic web started out as tiny clumps of matter in the early universe, which gradually grew into individual galaxies, and eventually galaxy clusters and filaments.
[...]
Nguyen, U-M physics professor Dragan Huterer and U-M graduate student Yuewei Wen examined the temporal growth of large-scale structure throughout cosmic time using several cosmological probes.

First, the team used what’s called the cosmic microwave background. The cosmic microwave background, or CMB, is composed of photons emitted just after the Big Bang. These photons provide a snapshot of the very early universe. As the photons travel to our telescopes, their path can become distorted, or gravitationally lensed, by large-scale structure along the way. Examining them, the researchers can infer how structure and matter between us and the cosmic microwave background are distributed.

Nguyen and colleagues took advantage of a similar phenomenon with weak gravitational lensing of galaxy shapes. Light from background galaxies is distorted through gravitational interactions with foreground matter and galaxies. The cosmologists then decode these distortions to determine how the intervening matter is distributed.
[...]
The findings potentially address the so-called S8 tension in cosmology. S8 is a parameter that describes the growth of structure. The tension arises when scientists use two different methods to determine the value of S8, and they do not agree. The first method, using photons from the cosmic microwave background, indicates a higher S8 value than the value inferred from galaxy weak gravitational lensing and galaxy clustering measurements.

Neither of these probes measures the growth of structure today. Instead, they probe structure at earlier times, then extrapolate those measurements to present time, assuming the standard model. Cosmic microwave background probes structure in the early universe, while galaxy weak gravitational lensing and clustering probe structure in the late universe.

The researchers’ findings of a late-time suppression of growth would bring the two S8 values into perfect agreement, according to Nguyen.

DOI: https://doi.org/10.1103/PhysRevLett.131.111001 [doi.org]

Original Submission