Belgian scientist Francis Halsen received the Nobel Prize in Physics in 2026, which recognized years of scientific work and marked an important step for modern astronomy. He played a crucial role in the creation and development of IceCube—an observatory installed beneath the Antarctic ice that allows for the study of extreme phenomena in the universe by detecting neutrinos.
This topic was covered on the program 'Olhar Espacial' on Friday (the 30th), where physicist Alexandre Charman discussed how the detection of these particles expands the possibilities for studying space.
Charman, who has extensive experience as an astronomer, theoretical physicist, data specialist, lecturer, and author of eight books, as well as co-author of 'Cosmic Real Estate Bank' published by Estrela Cultural, and Director of Astronomy at the Rio de Janeiro Planetarium Foundation, explained the characteristics of neutrinos.
Neutrinos are subatomic particles that have no electric charge and are among the least massive known. Due to their extremely rare interaction with matter, they can pass through planets, stars, and even the human body; it is estimated that about 100 trillion such particles pass through each person every second.
Charman noted that 'neutrinos have been described as the smallest amount of reality ever presented to humanity. They are the lightest material particles in the entire universe, surpassed only by massless bosons. Furthermore, they arise naturally as a result of radioactive decay known as beta decay.'
The difficulty in detecting these particles prompted scientists to create a structure capable of using the Antarctic ice itself as a detector. The concept was developed back in 1988, and it took over two decades of technological development before IceCube began full operation in 2010.
The observatory, located at the South Pole, covers an area of approximately one cubic kilometer of deep ice. Its structure includes 5160 optical sensors distributed along 86 vertical cables located at depths ranging from 1.45 to 2.45 kilometers. This configuration allows for the recording of light signals generated when neutrinos interact with matter.
Unlike traditional telescopes, which capture light emitted or reflected by celestial bodies, IceCube identifies particles reaching Earth from different regions of the universe. Since neutrinos have no charge, their trajectories are not deflected by magnetic fields. Thus, the direction of arrival provides important clues about the location of their cosmic sources, including extremely energetic natural particle accelerators.
Detection occurs when a neutrino interacts with an atomic nucleus or an electron in the ice, producing electrically charged particles. As they pass through the medium, they can move faster than light travels through that material. This process generates a short bluish flash known as Cherenkov radiation.
The optical sensors register these flashes and transmit the data to researchers. Based on the distribution and arrival time of the light signals, scientists can estimate the particle's energy and reconstruct its direction of arrival. This information helps study the phenomena responsible for producing neutrinos.
During the program, Charman also touched upon concepts of quantum mechanics and the possibility that a particle can exist in multiple states simultaneously. 'In quantum mechanics, there is a real possibility that a particle can occupy two states at once. The famous thought experiment of Schrödinger's cat perfectly illustrates this theoretical strangeness. Any quantum system remains in superposition until scientists perform a direct observation.'
IceCube continues to operate and is undergoing modernization to expand its observational capabilities. Among future prospects is the IceCube-Gen2 project, which aims to significantly increase the volume of detection and the sensitivity of the observatory. This initiative could potentially reveal new neutrino sources and deepen the study of the most energetic phenomena in the universe.
