His decades of research contributed to the development of a completely new method of observing the universe (neutrino astronomy).
According to the Turkish news agency Anadolu, Francis Halzen's idea is just as audacious as the place where it's being tested: transforming a 1-cubic-kilometer block of Antarctic ice into a telescope capable of observing nearly invisible particles flying in from the farthest reaches of the universe.
The Royal Swedish Academy of Sciences has honored Professor Halzen "for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of cosmic origin." Mark Pearce, Chairman of the Nobel Committee for Physics, said Professor Halzen led the international research team that created the extraordinary scientific instrument. "His perseverance and scientific vision have paved the way for a new field of astronomy," Pearce remarked.
From Belgium to Wisconsin (USA)
Halzen was born on March 23, 1944, in Tienen, Belgium. He studied mathematics and physics at KU Leuven University. He received his master's degree in 1966 and completed his doctoral dissertation on the symmetry breaking of hadron composite particles in 1969.
After working as a research scientist at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland , he was invited to the University of Wisconsin-Madison for a research assignment initially planned for only six months. Halzen joined the physics department at the University of Wisconsin-Madison in 1972 and remained there for over five decades. He became a Vilas Research Professor and Gregory Breit Professor of the Year, working in the intersection of particle physics, astrophysics, and cosmology.
The early stages of his career coincided with the development of the Standard Model in particle physics. He researched the application of this model to particle accelerators and cosmic ray studies. He also co-authored Quarks and Leptons, a textbook that later became widely used in particle physics courses.
However, by the mid-1980s, he began to shift his attention to neutrinos – electrically neutral particles with extremely small masses that rarely interact with matter. It is this elusive nature that has earned them the nickname "ghost particles," but also makes them potentially powerful astronomical messengers.
Unlike light, neutrinos can pass through gas, dust, planets, and other forms of matter without being absorbed or deflected. According to Halzen, studying these particles could help scientists "observe things in the universe that cannot be seen in any other way."
Building telescopes beneath the ice.
The challenge lies in detecting neutrinos. Neutrinos can travel across enormous distances without colliding with any atoms. Therefore, researchers need an extremely large detector located in a dark environment to observe these rare interactions that actually occur.
In 1987, Halzen began the AMANDA project to test the feasibility of installing highly sensitive light-detecting devices deep inside the Antarctic ice sheet.
Researchers used hot water to drill holes thousands of meters deep into the ice and lowered cables fitted with optical sensors before the water froze again. The AMANDA project demonstrated that the ice at this depth was clear and stable enough to act as a particle detector. This experiment became the technological foundation for the much larger-scale IceCube Neutrino Observatory.
Construction of the IceCube Observatory began in 2004. The final cable was lowered into the ice in December 2010, and the first official scientific operation with full equipment commenced in May 2011.
The completed IceCube observatory comprises 5,160 optical sensors installed inside a massive block of Antarctic ice weighing approximately one billion tons. When a neutrino accidentally collides with an atomic nucleus, it creates a charged particle that emits a faint blue light, known as Cherenkov radiation. The sensors record this light, allowing researchers to estimate the neutrino's energy and direction of travel. "We started on a small scale and surprisingly, we overcame all those obstacles," Halzen shared.
A turning point for the IceCube Observatory came in 2013, when the research team published evidence of high-energy neutrinos originating from outside the solar system. This discovery confirmed that particles born from some of the most powerful celestial bodies in the universe could be detected through the ice sheet in Antarctica. Another significant breakthrough occurred in September 2017, when the IceCube Observatory detected a neutrino with an estimated energy of 290 trillion electron-volts and quickly notified other observatories.
Other observations linked this particle to TXS 0506+056, a distant active galaxy driven by a supermassive black hole located approximately 4 billion light-years from Earth. This event provided the first compelling evidence for the origin of high-energy cosmic neutrinos, and demonstrated the potential of combining neutrino detection data with observations from traditional telescopes.
Since then, the IceCube Observatory has been used to study cosmic rays, dark matter, neutrino properties, the Milky Way, and active galaxies.
Prior to receiving the Nobel Prize, Halzen had been awarded numerous other prestigious prizes, including the Balzan Prize, the Bruno Pontecorvo Prize, the IUPAP Yodh Prize, and the 2026 Medal for Outstanding Research Achievement from the American Physical Society. He was elected a member of the National Academy of Sciences in 2024.
Professor Halzen (82 years old) received the news of the Nobel Prize while in Italy and described it as an unexpected surprise. As the sole recipient, he will receive the entire prize money, worth approximately $1.2 million.
Source: https://baotintuc.vn/chan-dung-chu-nhan-nobel-vat-ly-san-hat-ma-o-nam-cuc-post1391936.html
