Seen through the eyes of a giant, the galaxies of our Universe cling like foam to the surface of an eternal ocean, emerging in clumps and ropes around the inky voids.
This sparkling web took eons to come together, gradually congealing under the direction of gravity from what was, billions of years ago, an evenly distributed fog of white-hot particles fresh from the oven of the Big Bang.
As slow as this growth seems to us mere mortals, University of Michigan physicists Nhat-Minh Nguyen, Dragan Huterer and Yuewei Wen want to slow it down even further, thereby solving one of the most vexing problems in Science.
Their suggestion to make changes to the model that currently best describes our Universe could resolve an important conflict in observations of the increasing size of space.
Complain as much as you might about not being able to get something for free these days, there’s more empty space up there today than yesterday. Something is growing nothingness, squeezing through the gaps between galaxies to gently push aside the large-scale structure of the Universe at an ever-increasing rate.
Since we don’t know what’s behind this mysterious commotion, we call it dark energy.
“If gravity acts as an amplifier reinforcing disturbances of matter to grow into a large-scale structure, then dark energy acts as an attenuator dampening these disturbances and slowing the growth of the structure,” explains Nguyen, lead author of a study on large-scale disturbances. the growth of the structure.
“By examining how cosmic structure came together and grew, we can try to understand the nature of gravity and dark energy.”
The precise rate of expansion, known as the Hubble constant (H0), is not at all clear. By measuring how certain types of exploding stars recede into the distance, you could get an acceleration of 74 kilometers per second per megparsec. Using the “light echo” of stretched radiation still bouncing back after the Big Bang – the cosmic microwave background (CMB) – H0 is closer to about 67 kilometers per second.
This may seem small, but the discrepancy has persisted over enough investigations that it can no longer be considered an insignificant error.
Nguyen, Huterer, and Wen took a new look at the flat concordance cosmological model ΛCDM as a potential source of erroneous assumptions. If cosmology were a game of chess, it would be the chessboard and pieces arranged on the tiles of general relativity, moved by the push of dark energy and aligned by the gravitational influences of dark matter.
By rewinding the chess pieces we see today, we can actually see how the game began, from a moment of rapid inflation, to when the first stars collapsed, to the formation of galaxies and their eventual emergence into gargantuan, interconnected threads.
If, for some reason, this process deviates from what is predicted by the concordance model, preventing the growth of the large-scale structure of the Universe, the tension between the different measurements of the accelerated expansion of the The Universe would disappear.
The researchers used a combination of measurements involving ripples in the cosmic web, gravitational lensing events, and details in the cosmic microwave background to reach a statistically convincing conclusion that the cosmic web is growing more slowly than predicted by the flat concordance cosmological model ΛCDM.
“The difference between the growth rates that we potentially discovered becomes more significant as we approach the current situation,” says Nguyen.
“These different probes individually and collectively indicate growth suppression. Either we are missing systematic errors in each of these probes or we are missing late new physics in our standard model.”
Although there are no obvious contenders for what might hold back the growth of the cosmic web, future measurements of the large-scale structure of the Universe could at least indicate whether there is a need to explore this idea in more depth.
It took 13.7 billion years for the Universe to be this beautiful. We can wait a few more years to discover the secrets of such fine cosmological wrinkles.
This research was published in Physical Examination Letters.
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