Nicole Thomas from Bellville South researches astrophysics, studying black holes and galaxy evolution

Nicole Thomas's path into astrophysics began in Bellville South and led her to the International Scientific Meeting in Lindau, Germany, in 2019, where she joined leading young researchers and Nobel laureates. A former student of Kasselsvlei High School and the University of the Western Cape (UWC), she currently studies supermassive black holes and galaxy evolution. After earning a PhD in astrophysics, she built a career that moved her from local classrooms to the international scientific community.

Her story is an example of curiosity, determination, and the opportunities provided by education, which may inspire youth who do not see themselves in fields like astrophysics.

Childhood Fascination with the Universe

Thomas shared that her interest in science arose from a desire to understand how things function, especially when the answers were not obvious. She noted that she was always fascinated by the world and wanted to know how and why things worked, and the more complex and mysterious the phenomenon, the more she enjoyed it.

Since there was no internet access at home at the time, her introduction to astronomy and space came through television documentaries. Her father often watched documentaries on Discovery Channel and National Geographic, where she first heard about the concept of astronomy, and this interest subsequently expanded beyond Earth and into space.

From UWC to Black Hole Research

After studying physics at UWC, Thomas continued her studies under the National Programme for Astrophysics and Space Sciences at the University of Cape Town, before returning to UWC for further postgraduate research. Ultimately, she received her PhD in astrophysics from UWC, specializing in supermassive black holes and their influence on galaxy development.

Her field of study investigates the processes of black hole growth, the ways they release enormous amounts of energy, and how their activity can affect the galaxies they reside in. Understanding these processes helps scientists study how galaxies evolve and change over time. Thomas's academic journey demonstrates how scientific education in Cape Town can lead to internationally significant research.

Overcoming Expectations and Sacrifices

Thomas stated that she never viewed her background as an obstacle to her ambitions. She considered her environment simply normal life, so she saw no reason to perceive it otherwise. Although studying astrophysics might have surprised some people, she emphasized that her parents, friends, and school supported her scientific interest.

She faced the stereotype that girls are incapable of doing mathematics, but she did not allow her gender, race, or origin to define her achievements. Thomas said she was raised not to make excuses. She also acknowledged the role of opportunities and personal circumstances in her journey. Despite not being able to enroll in the university she was initially accepted into for astronomy, she still managed to obtain higher education.

Her career opened new possibilities but also required sacrifices, including time spent away from home and the need to balance personal priorities with the demands of scientific inquiry.

Advice to Young People Interested in Science

Thomas is convinced that young people interested in astronomy and other scientific disciplines today have more ways to explore their interests than ever before. She pointed out that a vast amount of knowledge is available through social media, Google, or artificial intelligence, which can serve as powerful tools for studying specific topics.

Furthermore, she mentioned opportunities in Cape Town for young people to interact with scientists and professionals in science, technology, engineering, and mathematics (STEM). She noted that Cape Town is a wonderful place to connect with astrophysicists, space scientists, or other STEM professionals. While some events, such as the Planetarium and Iziko Museum, may have a small fee, various free events take place throughout the year.

Thomas added that many scientific institutions collaborate with schools by conducting educational programs, and universities organize open days and other events that introduce students to scientific careers. Her advice underscores the value of asking questions, exploring interests, and utilizing educational opportunities, whether online, in school, or through local scientific institutions. Thomas's journey, from Kasselsvlei High School classrooms to researching the most complex objects in the universe, shows how early curiosity can transform into a career studying what lies beyond the known.

Astrophysicists were able to reconstruct images of how the Universe emerged from a state of darkness. Light bubbles began to appear around the first galaxies, which grew, merged, and gradually dispersed the cold gaseous fog enveloping the primitive cosmos.

These images, presented by an international group of researchers on Sunday (the 25th), were obtained using Lumina—a simulation run on a supercomputer. The scientists input conditions of the Universe immediately after the Big Bang, measured by satellites, and allowed the laws of physics to operate. The computer then 'played back' the evolution of this Universe over the first two billion years.

The results of the work were published on Tuesday (the 26th) in the scientific journal Monthly Notices of the Royal Astronomical Society. The data obtained generally correspond to what telescopes have already observed during this period. However, there is a significant shortcoming: the simulated Universe contains fewer giant galaxies than those discovered by the James Webb Space Telescope.

According to the authors, this indicates that the galaxies of the young Universe evolved faster than current theories allow to explain. The modeled section of the Universe is about 1.6 billion light-years across one side, allowing researchers to trace how different regions evolved differently. For this, the computer tracked the movement of hundreds of billions of gas and dark matter particles. Dark matter is invisible, but its gravity serves as the framework determining where galaxies form.

The calculation was performed on Frontier, one of the world's most powerful supercomputers located in the United States.

How the Universe stopped being dark

Immediately after the Big Bang, the Universe was very hot. As it expanded, it cooled and filled with gas made of hydrogen and helium—the simplest elements. This gas acted like a haze, blocking higher-energy light, such as ultraviolet, which could not travel far. This stage is known as the era of cosmic darkness.

The fog began to dissipate when the first stars appeared, approximately 100 million years after the Big Bang. Their light was strong enough to 'break up' the surrounding gas atoms. The disrupted gas allowed light to pass through, and the Universe became more transparent. The images show that this did not happen simultaneously or uniformly. Areas with a high concentration of galaxies lit up first, similar to areas illuminated earlier in a city. Large voids between them remained dark for much longer.

In the simulation, the last pockets of fog disappeared only about 1 billion years after the Big Bang. This later completion is consistent with measurements made by astronomers previously. The model also confirms that stars performed the main work. Black holes contributed less to this initial stage.

However, helium required a second round. Its atoms are harder to break up, requiring light much more powerful than that from ordinary stars. This light came from quasars—giant black holes that intensely radiate while consuming gas. Since quasars are rare and very powerful, the bubbles they created were significantly larger and more distributed. This second stage started later than the first and was almost complete only by two billion years.

Lumina is the first simulation of this level of detail to demonstrate both the stellar and black hole-related stages. Previous models stopped earlier. Each of these phases also heated the gas. The simulation also shows that even before reaching starlight, X-rays emitted from galaxies were already heating the fog. This detail is useful for radio telescopes trying to capture the extremely faint signal of gas from that era, which has not yet been detected.

What the simulation does not yet explain

Comparison with the James Webb Space Telescope raises more questions for Lumina. Since 2022, the telescope has been discovering galaxies in the young Universe that are larger and brighter than theories predicted. The simulation reproduces small and medium-sized galaxies well. But regarding the largest ones, whose mass exceeds the Sun by hundreds of billions of times, it lags behind. The earlier in the Universe's history, the greater the discrepancy.

The authors propose several possible explanations. Perhaps these galaxies formed stars faster than previously thought, or produced more massive stars. It is also possible that the rules used by scientists to describe the Universe need adjustment. Or, more simply, that the Webb measurements have a larger margin of error than assumed.

The full Lumina data will be available to other scientists in 2028. The group is already preparing new studies to compare the simulation with telescope observations. The value of Lumina lies both in what it confirms and what it gets wrong. Where the simulation matches telescope data, it confirms that known physics adequately explains the infancy of the Universe. Where it falls short, it points to the exact place where this physics still requires revision.