Stockholm. Sometimes it takes something big to find something very small: With his vision for a gigantic ice cube, the Belgian-American researcher Francis Halzen made a decisive contribution to recording the tiniest elementary parts - and is now being awarded the Nobel Prize in Physics for this.
The Royal Swedish Academy of Sciences in Stockholm said Halzen made significant contributions to the IceCube neutrino observatory - a cubic kilometer of glacial ice in Antarctica equipped with sensors. “His tenacity and scientific vision paved the way for a new kind of astronomy,” said Physics Nobel Committee Chairman Mark Pearce.
Halzen, a professor at the University of Wisconsin in Madison and now 82 years old, recognized that the ice at the South Pole was suitable for tracking neutrinos - often called ghost particles. He first presented his plans in 1988.
With the “IceCube”, which was fully commissioned in 2011, the first detection of high-energy cosmic neutrinos was achieved, according to the particle research center Desy (German Electron Synchrotron). “A new observation window into the most extreme regions of our universe had been opened.”
Germany is significantly involved in the IceCube Collaboration and represents the second largest national contingent after the USA. In addition to Desy, the Karlsruhe Institute of Technology (KIT) is also involved. German research groups not only collaborate scientifically, but also developed central components of the observatory.
The award winner was in Italy on Tuesday. The prize was “a big surprise” and “of course I didn’t expect it,” said Halzen when the Nobel Committee brought him to Stockholm to announce the prize. It is a great joy – and feels “strange” to be awarded the Nobel Prize.
Discussing his plans for his big day, the newly crowned Nobel laureate said he is currently working on a scientific proposal and hopes the prize will increase the chances of it being accepted.
Halzen was born in Tienen, Belgium, in 1944 and is now a US citizen. In 1969 he received his doctorate from the Catholic University of Leuven. There they were proud and overjoyed, as a spokeswoman for the university told the German Press Agency.
Christopher Wiebusch from RWTH Aachen works on the “IceCube” project and has known Halzen for years. "I believe that there is a very big cultural gain because we are learning to see the universe in a new way. New views of the universe have ultimately always had long-term effects on humanity," Wiebusch told dpa - and described Halzen as a person with charisma that he has rarely experienced. He is “very smart, but also very approachable”.
Neutrinos are among the most mysterious elementary particles. On average, ten billion of them hit every square centimeter of the earth's surface every second - roughly the area of a fingernail. They play an important role in nuclear physics, for example in nuclear fusion inside the sun. However, the neutrinos that “IceCube” is searching for are millions to billions of times more energetic and are created in stellar explosions and in the vicinity of supermassive black holes in distant galaxies.
Neutrinos are quite shy creatures: they hardly interact with ordinary matter. In order to detect the volatile particles, large amounts of matter are required that consist of substances that are as pure as possible. One such substance is water, for example - in the Antarctic ice it is present in large quantities in a sufficiently pure form.
If a neutrino reacts - which rarely happens - with a water molecule, electrically charged particles are created that race through the ice at almost the speed of light and emit light in the process, the so-called Cherenkov radiation. According to Desy, the one-cubic-kilometer detector captures these light signals using several thousand light sensors that are melted into glass balls on long cables deep into the polar ice.
Physicists hope for a lot from such neutrino research: insights into dark matter, the Big Bang and physics beyond the standard model of particle physics. The interactions discovered by the facility could reveal cosmic phenomena that are still unknown, the Nobel Committee said.
“So far we are only seeing the tip of the iceberg – only a very small part of the neutrino sky has been resolved,” explained DESY researcher Marek Kowalski. The IceCube Collaboration is therefore planning to expand the detector: “The expansion to IceCube-Gen2 will increase the size of the detector to a gigantic eight cubic kilometers and increase the detection rate of cosmic neutrinos tenfold,” says the website.
In the 125th year of the Nobel Prize in Physics, there is something special: for the first time in the foundation's history, the names of the Nobel Prize winners for physics, chemistry and economics will be announced by a woman. Belgian-born Ellen Moons took up her post at the start of the year as the new Secretary General of the Royal Swedish Academy of Sciences (KVA) in Stockholm, which announces the Nobel Prizes in the three prize categories every year. She is the first woman to hold this position since the academy was founded in 1739.
“For me it’s pretty normal to be the first woman in physics or to be one of a minority of female physicists,” said the 60-year-old. “But of course this is a very special event: we are celebrating science today, and it is a great pleasure for me to act as its spokesperson.”
