Universe map

A new map of the Universe highlights an incomprehensible discrepancy between the accepted cosmological model and the results obtained
An artist’s impression of the cosmic web. It looks like a vast structure resembling a spider web mostly purple and some orange filaments on a black background. Credit: Volker Springel Max Planck Institute for Astrophysics et al.

Scientists have created the most detailed map of the universe ‘s matter, which highlights that something might be missing in the cosmological model. Created by combining data from two telescopes that observe different types of light, the latest map has revealed that the universe is less clumpy than previously predicted by models. A clear sign that the vast cosmic network connecting galaxies is less understood than scientists thought.

A Strange Discrepancy

According to our current understanding, the universe is a vast network of celestial superhighways that intersect, formed by hydrogen gas and dark matter. Taking shape after the chaotic Big Bang, these superhighways formed as clumps from the boiling broth of the young universe. Where more threads of the network intersected, there was enough matter to form galaxies.

But the new map of the universe, published on January 31, accompanied by three separate scientific studies (ref.) (ref.) (ref.) published in the journal Physical Review D, shows otherwise. In many parts of the cosmos, matter is less dense and more uniformly distributed than it should be. “It seems that there are a bit fewer fluctuations in the current universe than we predict assuming our standard cosmological model anchored to the primordial universe” said co-author Eric Baxter, an astrophysicist at the University of Hawaii.

The History of the Universe

According to the standard model, the universe started to take shape after the Big Bang, when the young cosmos was teeming with both matter and antimatter particles, which annihilated each other upon contact. Most of the building blocks of the universe were swept away in this way. But the fabric of spacetime in rapid expansion, along with some quantum fluctuations, caused some pockets of primordial plasma to survive.

Gravity soon compressed these pockets of plasma on themselves, heating up the matter as it was crushed against each other. At that point, most of the universe’s matter was distributed as a series of thin filaments surrounding countless cosmic voids. Once this matter, mostly hydrogen and helium, cooled enough, it coagulated further to give birth to the first stars, which in turn forged heavier elements through nuclear fusion.

How was the map built

To get to the latest map of the Universe, researchers combined observations made by the Dark Energy Survey in Chile and the South Pole Telescope, located in Antarctica. The former scanned the sky in ultraviolet, visible and near-infrared frequencies from 2013 to 2019. The latter studies microwave emissions that make up the background radiation. Although they observe different wavelengths of light, both telescopes used a technique called gravitational lensing to map the aggregation of matter.

Gravitational lensing occurs when a massive cosmic object is located between our telescopes and its source. So light from a point behind the massive cosmic object appears distorted, proportional to the mass present in that space. This makes gravitational lensing an excellent tool for tracing both matter and its mysterious dark matter. In fact, despite dark matter constituting 85% of the Universe, it does not interact with light except by distorting it with the gravity generated by its mass.

With this approach, researchers used data from both telescopes to locate the position of matter and eliminate errors from one telescope by comparing it to the other. “It works like a cross-check, so it becomes a much more robust measure if you use only one or the other” said lead author Chihway Chang, an astrophysicist at the University of Chicago, in a statement.

The possible explanations for the discrepancy

Universe map produced by researchers fit perfectly into our understanding of how the cosmos has evolved, with one key discrepancy. The cosmos appears more uniformly distributed and less grouped than the standard cosmology model would suggest. There are two possible explanations.

The first is that we are simply observing the Universe too imprecisely. So the deviation from the model will disappear as we have better tools to scrutinize the cosmos. The second, and more significant, possibility is that our cosmological model lacks important physical laws. Discovering which laws are missing will require cross-checks and mappings, as well as a deeper revision of our understanding of cosmological constraints.

“There is currently no known physical explanation for this discrepancy” the researchers wrote in one of the studies. “The cross-analysis of future studies will allow significantly more powerful correlation studies that will provide more precise and accurate cosmological constraints that will allow us to continue to stress the standard cosmological model”.

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