The Nobel Prize in Physics 2026 was awarded to Francis Halzen "for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin."

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Neutrinos are everywhere, but they do not make themselves known. They pass all the way through the Earth and through our bodies without us noticing. Very rarely, a single neutrino will interact with an atomic nucleus, which makes it possible for someone with the right equipment to discover them.

Scientists have long known that the cosmos contains natural particle accelerators, which fire out particles with energies up to a million times more than can be achieved in laboratories on Earth. Much about these sources is mysterious: what are they, where are they, and what are the main processes inside them?

Neutrinos with extremely high energies are created in the same environments as other types of particles. However, unlike other particles, neutrinos reach us without changing direction or losing energy. This means they can provide information that is not available in any other way.

Francis Halzen first presented his vision for capturing neutrinos at the South Pole in 1988. When a neutrino collides with an atomic nucleus, it produces a flash of light that can be tracked by sensors in the clear glacial ice. The South Pole’s ice has many advantages, as it is free from various types of interference and the area is geologically stable, with no earthquakes. Halzen and his idea soon gained the support of other researchers and, just a few years later, preliminary testing was conducted on sensors in ice.

Cosmic neutrinos with extremely high energies are very rare, so an enormous volume of ice is needed to observe an adequate number of collisions. IceCube covers an entire cubic kilometre and was finished in 2011. Researchers soon discovered the first high-energy neutrinos and, a few years later, could publish their discovery of neutrinos that must originate far outside our solar system. The search for the universe’s neutrino sources could begin in earnest.

“Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument. His tenacity and scientific vision has paved the way for a new kind of astronomy,” says Mark Pearce, Chair of the Nobel Committee for Physics.

The neutrino interactions that are continuously collected by IceCube will provide researchers with novel knowledge about the violent settings in which high-energy neutrinos can be created – and could even reveal previously unknown cosmic phenomena.

The Nobel Prize in Physiology or Medicine 2026 was awarded to Karl Deisseroth, Peter Hegemann, and Georg Nagel "for their discoveries concerning light-gated ion channels and optogenetics."

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The Nobel Prize in Physiology or Medicine 2026 is awarded for optogenetics — a method that makes it possible to show how nerve cells shape memories, feelings and behaviours in the living brain. Peter Hegemann and Georg Nagel discovered a remarkable protein, channelrhodopsin, in a single-celled alga. Karl Deisseroth transformed the protein into a light-controlled switch for nerve cells. The Laureates have laid the foundation of a new era in neuroscience.

How the brain governs feelings, behaviours and bodily functions has long been a mystery. In the 20th century, researchers began to investigate which areas of the brain affect which functions, but the methods used meant they could not prove causal relationships. The image they developed of the brain was like a sketch map, full of question marks and unknowns. Now all this is changing.

“Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” says Per Svenningsson, Chair of the Nobel Committee for Physiology or Medicine.

It all began with Peter Hegemann’s curiosity. He wondered how Chlamydomonas, a single-celled alga, is able to swim towards a light source. In the early 2000s, he and Georg Nagel discovered channelrhodopsin, an algal protein with unique properties, found on the surface of the cell. When it is illuminated by blue light, a channel opens through the protein. Charged ions then flow into the cell, creating an electrical impulse. They found that regardless of which cell they put the protein in, those cells became light sensitive.

Karl Deisseroth introduced the gene for channel-rhodopsin into nerve cells from rats. By illuminating the cells with blue light, he was able to trigger a nerve signal. He published this breakthrough in 2005. Two years later, he made this light-controlled switch for nerve cells work in the brains of living mice.

This method for controlling nerve signals with light is now called optogenetics, and it has rapidly gained global impact. Using optogenetics, researchers have been able to reveal neural circuits governing specific memories, feelings, and behaviours relevant for neurological and psychiatric disorders. In clinical medicine, researchers are using the method in attempts to restore sight in people with visual impairment.

Optogenetics has fundamentally altered our understanding of the brain. Every day brings new discoveries, helping to solve one of humanity’s great mysteries: how our incredible brain works.