Nobel Sunday Supplement

Instead, let's hit the real stuff.

Physics

Francis Halzen (University of Wisconsin–Madison, USA).

Halzen is the lead principal investigator of the IceCube neutrino telescope, which is literally an ice cube. A really big one: a cube of Antarctic ice a kilometer on a side, starting about 600 meters down.

🥉🚨 Bronze alert - IceCube observation of a high-energy neutrino candidate event at 2026/09/30 00:44:43 UTC. Find out more at: https://t.co/DJStthWuYt. #IceCubeAlert https://t.co/9DjzrZuDtC

— IceCube Neutrino Observatory (@uw_icecube) September 30, 2026

That's an artist's rendering of course, because it's buried under a half mile of ice. Here's another view of the telescope.

📍What do you do when the sun rises for the first time in six months? Play golf, of course! Read more about week 39 at the Pole ➡️ https://t.co/s81EfoYPDB 📸: Camille Parisel, IceCube/NSF #WeekAtThePole #IceCubeNeutrinoObservatory https://t.co/FQLgLUnvZJ

— IceCube Neutrino Observatory (@uw_icecube) October 2, 2026

It's actually very unusual for the Physics prize to be awarded to one person, but IceCube has really been Halzen's life work. But what does it mean?

A neutrino is a very light — very light, and in fact the actual mass is still undetermined, but they're way lighter than an electron. But they must have some mass, because they are observed to oscillate over time. In fact, for a while it was assumed they were massless, just like a photon, until that oscillation was observed. If they were actually massless, they would have to travel at exactly c — the speed of light. But Einstein's Special Relativity tells us anything travelling at the speed of light basically doesn't experience duration. A neutrino can't oscillate over time if it doesn't experience time. The weirdness doesn't stop there, though. Neutrinos only interact with other matter through the weak nuclear force, which is, well, weak. That makes it very improbable that a neutrino will interact with anything at all, leading to the observation that a neutrino would happily pass through a light-year of lead without noticing at all. On the very rare occasion a neutrino does interact, its energy is converted into some other energetic particles. These particles are very fast — faster than the speed of light in the material around them, in this case, ice. That produces a photon, what is called Cerenkov radiation.

The way IceCube works is each of those vertical shafts are holes drilled with hot water into which  a long string of sensitive light detectors are dropped.  Then the holes are filled with water and freeze back up. When a neutrino zips through the ice and troubles itself to interact at all, the resulting collision products generate a flash of Cherenkov light that is detected by the light detectors. The direction of the flashes then has some information about the path and energy of the neutrino.

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No one is putting an eyepiece on the neutrino telescope. The data are collected and mangled by computer, and converted into images. Like these.

This is a picture of the Sun taken at night, through the entire Earth. Look closely at thi pixelated image. It wasn't captured by a traditional telescope using light. It is a "neutrinograph"—an image created using subatomic particles called neutrinos. Neutrinos are often called "ghost particles" because they are generated in the Sun's burning core and fly undetected through almost all matter- including planets This incredible image was compiled over 503 days by the Super-Kamiokande (Super-K) detector, located 1,000 meters underground in a mine in Japan. Because neutrinos pass so easily through matter, the detector didn't need to "look up." It detected these particles after they had traveled all the way through the globe to reach the underground tank of water on the other side. It’s a stunning reminder that there is an entire invisible universe passing right through us every second. Image Credit: Super-Kamiokande Collaboration / NASA APOD Journal Reference: Y. Fukuda et. al, Measurement of the Solar Neutrino Energy Spectrum Using Neutrino-Electron Scattering, Phys. Rev. Lett. 82, 2430, DOI: 10.1103/PhysRevLett.82.2430 #Astrophysics #Neutrinos #SuperKamiokande #Physics #SpaceExploration

— Science & Nature (@ScienceIsNew) December 4, 2025

This is actually from another neutrino telescope. The IceCube people haven't posted any images that I can use due to copyright issues. 

So yeah, Charlie, but what does it all mean? Basically, lots of neutrinos happening are produced by very energetic events: little ones like atomic bombs, big ones like supernovas and supermassive black holes that form active galactic nuclei. These neutrino telescopes both confirm that we are starting to understand these processes a little better, and giving us a picture of what's happening around us that we couldn't get any other way. (Or see the video at the bottom.)

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Physiology or Medicine

Karl Deisseroth (Howard Hughes Medical Institute and Stanford University, USA), Peter Hegemann (Humboldt University of Berlin, Germany), and Georg Nagel (University of Würzburg, Germany).

This one is actually pretty cool, although maybe not quite as cool as a picture of the Sun taken through the Earth. The prize was awarded for their work in what they call optogenetics. Basically, they made chimera cells incorporating a gene for light sensitivity into mammalian nerve cells.  In general, the way a nerve cell works is that ion pumps push sodium to one side of the cell membrane, and potassium to the other side. Since the ions are out of balance, an event like a signal from another nerve cell loads up the target cell until it finally can't take it any more, and it opens channels through the cell wall. The ions pass through the channels, which produces an electrical current that becomes the nerve signal. We say the cell fires. (When I was at Duke, the professors all described these channels as acting like a revolving door, "but of course it isn't really like that." There was a lot of active research on trying to figure out how they really worked. Years later, electron microscopy got good enough to actually take pictures of these channels. And — surprise — they look like revolving doors.)

These genetically-modified cells have a new kind of if channel that's light sensitive. Shine a light on one of these cells, and it fires. Reliably. Which means they can in the laboratory fire these cells on command and see what happens — what cell fires next. They can start to build maps of the nervous system, cell by cell.

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Chemistry

Henri B. Kagan (Université Paris-Sud, France) and Kenso Soai (Tokyo University of Science, Japan).

One of the puzzles of biochemistry is that many chemicals — for example, DNA — have chirality: they are either right handed or left handed. In life on Earth, amino acids are almost always left-handed; sugars almost always right-handed. But when the same chemicals are made in a lab, they end up being a mix of both. 

What Kagan did was find a way of changing this balance to favor one handedness, Then Soai demonstrated a mechanism that results in very pure synthesis of chemicals with one handedness.

Why does this matter? It turns out that many drugs are also chiral — the active drug is either right or left handed. The opposite chirality may do nothing, or may even be harmful. This work promises improvements in drug synthesis, and may explain why life on Earth cares.

Interesting YouTubes of the Week

Shooting for the Stars

Even more shooting for the stars

More on IceCube

And that's it for this week. Friday's Sky Candy leaned real heavily on nebulae; those are always popular. And of course watch for next Week's Sky Candy on Friday, and the Sunday Supplement next Sunday.

(Today's column prepared with the able assistance of my orange cat Ginger, Captain of Chaos and Preventer of Productivity, who probably only added two hours to the work.)