Two recent investigations explored defining moments in the early cosmos, from the emergence of fundamental plasma to the development of stellar structures. Why these breakthroughs offer clues to the physical processes that shaped space.
When we talk about the origin of the universe, it's easy to imagine a starry sky forming at full speed or elementary particles hurtling through space in primordial chaos. Currently, two investigations, from very different perspectives, are providing insight into those earliest moments of cosmic history: one tracked the massive formation of stars and black holes in young galaxies, while the other studied how matter was able to transform into its most elemental forms under extreme conditions.
The first study, led by experts from the University of Kansas, reveals new details about galaxy formation during the so-called "cosmic noon," a time of high activity in space, using data from the James Webb Space Telescope (JWST). The second, from the Institute of Modern Physics of the Chinese Academy of Sciences, proposes a novel way to detect a fundamental reconfiguration of matter, known as the hadron-quark transition, in collisions of atomic nuclei in the early stages after the Big Bang.
Although they work on different scales, both share a common drive: to understand how the universe came to be as we know it. Each illuminates, from its own perspective, a piece of the larger puzzle.
Looking through the dust to see galaxies in their full splendor
During a period known as "cosmic noon," between 10 and 11 billion years ago, galaxies produced stars at a frantic pace. Astronomers were aware of this stage, but the dust that surrounds them, made up of tiny particles, made it difficult to clearly see what was happening inside them. To overcome this barrier, a team from the University of Kansas, led by Professor Allison Kirkpatrick, carried out the MEGA project using the JWST.
“Our goal with this project is to conduct the largest mid-infrared survey using JWST in multiple bandwidths,” the expert explained in a statement from the educational institution. This range of the electromagnetic spectrum is key because, at these wavelengths, one can see behind the dust to capture the birth of hidden stars.
To better understand this, looking in mid-infrared is like using special glasses that allow you to see inside a sandstorm. This reveals what is happening behind the curtain of material.
The project covered a region of the sky known as the Extended Groth Strip. This is an area particularly free of celestial pollution in the Milky Way, making it easier to observe much more distant objects.
It managed to analyze around 10,000 galaxies. Each one appeared in different colors and intensities depending on its age, amount of dust, and stellar activity. To obtain this data, the researchers combined images taken through four different filters from MIRI, an instrument on the James Webb Telescope specializing in mid-infrared light. They then superimposed layers of information from different colors to construct a complete final mosaic.
From pixel to catalog: the work behind the images
Transforming the images captured by the telescope into precise scientific information was a painstaking task. Bren Backhaus, one of the main people in charge of this process, explained that she had to correct defects such as dead pixels or scratches on the instrument. “The first step is to correct or at least instruct the software to ignore them,” she explained.
Once the data was cleaned, Backhaus aligned the images taken through different filters to create scientific mosaics ready for analysis. She then compiled a catalog of how much light each galaxy emitted in the different observation bands.
The procedure is similar to joining together scattered pieces of a huge jigsaw puzzle: first, correcting imperfections in each fragment, and then fitting them together precisely to reveal the complete scene. In this way, MEGA not only made it possible to see the galaxies, but also to measure their intensity and structure with unprecedented precision.
Thanks to this meticulous work, astronomers can now identify how supermassive black holes at the heart of galaxies grew, reveal clues about how these cosmic systems changed shape over billions of years, and understand how the stars that make up half of the current stellar mass of the universe were assembled. By being able to peer behind the dust with unprecedented sensitivity, the project opens a new window into reconstructing the hidden past of space.
In Search of Primordial Matter
While astronomers scrutinized the distant origins in search of stars and dust, another group of scientists, from nuclear physics, explored something even more primitive: the conditions under which matter itself changed its fundamental structure.
Understanding how and when this transformation occurred not only helps reconstruct the earliest moments of the cosmos, but also allows us to verify fundamental predictions of modern physics about the behavior of matter at extreme temperatures and densities.
The Institute of Modern Physics of the Chinese Academy of Sciences, led by Gao-Chan Yong, proposed a new way to detect whether, in heavy ion collisions, a quark-gluon plasma (QGP) was formed—a state in which the building blocks of matter flow freely, as occurred in the earliest moments of the universe. “Similar to how fingerprints identify individuals, the production ratios of different particles in collisions contain crucial information,” he explained in an academic article.
In simple terms: when two atomic nuclei, such as those of gold or calcium, collide at extremely high speeds, they generate such extreme temperatures that quarks (the building blocks that make up protons and neutrons) could be released, forming a material state that existed shortly after the Big Bang.
The researchers simulated these collisions and observed that, when comparing light systems (such as calcium) with heavy systems (such as gold), the production of certain particles (particularly Lambda hyperons and positive K mesons) showed different patterns if a quark plasma arose.
To visualize this, it's like comparing the steam released when boiling water in a small glass versus a giant pot. If the steam released in the pot is much smaller than expected, something unusual is happening: in this case, a phase transition in matter.
Toward a clearer map of the early universe
One of the main advantages of the new method proposed by Yong and his team is that it helps reduce systematic errors. By comparing the same particles in collisions between heavy and light systems, many of the uncertainties inherent in simulation models are eliminated. “Using the ratio of observables from two reacting systems can obviate many theoretical uncertainties in transport model calculations,” the authors stated.
Furthermore, the results were validated using another independent system, PACIAE, which confirmed that the observed patterns were not an artifact of the initial simulation. This new tool will allow future experiments to more precisely search for signs of a phase transition in matter, tracing in greater detail the so-called “phase diagram” that describes how the internal structure of space changes under different extreme conditions.
Unambiguously detecting the emergence of quark-gluon plasma would be like discovering the fossil traces of the original state of matter, as it existed just microseconds after the Big Bang. This breakthrough would bring science closer to answering one of the great questions about how the universe went from being a free ocean of elementary particles to building the basic building blocks of everything that exists today.
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