KELLY MCEVERS, HOST:
Today the Nobel Prize in physics was awarded to two researchers. Takaaki Kajita, of Japan, and Arthur McDonald, of Canada, won for showing that particles called neutrinos have mass. NPR's Geoff Brumfiel has more on the win.
GEOFF BRUMFIEL, BYLINE: When Arthur McDonald got the call from Stockholm, he gave his wife a hug. He spoke to his mom and texted his kids. The only person he couldn't tell was his dad.
ARTHUR MCDONALD: My father unfortunately passed away a couple of years ago. I'm actually wearing a sweater that was his, which is my way of dealing with that. He would love to be here today.
BRUMFIEL: That's very sweet. Was he a physicist?
MCDONALD: No, he was an accountant, but a very good one.
BRUMFIEL: McDonald has devoted his career to studying neutrinos. Neutrinos are fundamental particles. Billions, even trillions of them are streaming through your body right now. They pass right through you like you're not even there. Neutrinos are so hard to see...
MCDONALD: You have to build a detector the size of a 10-story building in order to observe one an hour.
BRUMFIEL: You heard that right - a building-sized detector will see just one little neutrino in an hour. McDonald and the other winner made a big discovery in separate detectors on opposite sides of the planet. These detectors are isolated deep underground in abandoned mines.
Joe Lykken, who's deputy director of the Fermi National Accelerator Laboratory, says these are some of the oddest labs in the world.
JOE LYKKEN: You walk down a tunnel and then all of a sudden there's a door. You walk through the door, and you're in a modern science lab where the walls are clean and there's electronics and there's an espresso machine and there's Wi-Fi. It's really surreal. It's a strange feeling.
BRUMFIEL: What's even stranger is what today's prize winners found 15 years ago. There are different kinds of neutrinos, and the scientists were counting them by type. They knew how many of each type they should find, but the numbers just didn't add up. The only possible explanation was the neutrinos were changing from one type to another.
LYKKEN: And this is really quite remarkable when you think about it because we do believe neutrinos are elementary particles, and it almost seems like a contradiction to say that one elementary particle can turn into a different elementary particle. It's very mysterious that that can happen all, and it wasn't believed until we had definitive evidence of it.
BRUMFIEL: There's another reason nobody believed it. For neutrinos to change type, the laws of physics say they have to have mass. But the best theories at the time predicted neutrinos were weightless. In other words, these experiments showed the best theories were wrong. Even today, the U.S. and other countries are still conducting experiments to figure out what's going on.
LYKKEN: We're close to breaking through, I think, to the next level.
BRUMFIEL: As for Nobel winner Arthur McDonald, now that he's told his family, he's got a few more phone calls to make - to the other physicists who he worked with.
MCDONALD: The total number of people who were authors on the physics papers that we published were 277.
BRUMFIEL: McDonald says he's not yet sure how to divvy up the prize money, but he's looking forward to celebrating with them. Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.
