AUDIE CORNISH, HOST:
Scientists at the University of California want you to turn your phone into a cosmic ray detector. The first step, of course, is to install an app. If enough people do, they think they'll be able to solve the mystery of what's producing the very energetic particles that occasionally hit the Earth. We're going to revisit this story now with NPR science correspondent Joe Palca.
JOE PALCA, BYLINE: Daniel Whiteson and his buddy Michael Mulhearn are physicists trying to unravel the fundamental laws of the universe. And they almost never work on projects that are small.
DANIEL WHITESON: The two of us both work in these enormous collaborations of about 3,000 scientists. And while that's very interesting and you meet a lot of sharp people, it's also nice sometimes to do a smaller project where you can be in control of what's happening.
PALCA: You see, these guys work on the giant particle accelerator called the Large Hadron Collider in Geneva, Switzerland. One day back in November 2013, Whiteson says he and Mulhearn were visiting a local Geneva watering hole.
WHITESON: We were having beers and thinking what could we do that's smaller scale that we can handle ourselves? And while we were chatting, we were, of course, fiddling with our smartphones, and that's when we realized - hold on a second, these smartphones can actually be used as particle detectors.
PALCA: That's because smartphones use something called a CMOS chip inside their cameras, the same kind of chips used to detect particles generated by the Large Hadron Collider. The particles they figured they might be able to detect are what's known as high-energy cosmic rays. These particles are far more energetic than anything that even the Large Hadron Collider can produce, but nobody knows what's producing them.
WHITESON: That means that there's something out there in space - some unknown new object in space - that's capable of generating particles at a very, very high energy.
PALCA: Physicists would dearly love to figure out what's producing these energetic particles.
WHITESON: The problem with figuring out where these things are coming from is that they're very rare.
PALCA: That's where the smartphones come in. Whiteson and his pals are building an app that turns the CMOS chip in the phone's camera into a particle detector. They're hoping millions of people all over the globe will download the app. When a high-energy cosmic ray hits the top of Earth's atmosphere, it creates a shower of new energetic particles.
WHITESON: So if we have a bunch of users nearby each other, all running the app, then they will all see hits in their phone. They'll see particles being detected by our app in their phone at the same moment.
PALCA: And by analyzing the distribution of the particle shower detected by the phones, Whiteson says they'll learn more about the high-energy cosmic rays that produced the shower - that's the idea, anyway. Whiteson says the reaction from other astrophysicists to his smartphone-as-particle-detector scheme ranges from bemused to skeptical. But he thinks that's reasonable.
WHITESON: We don't yet know if it's the best idea we ever had or just the silliest idea we ever had. One thing we're certain of, though, is that it's been one of the funnest projects to work on.
PALCA: If you want to join the fun, there's a link for signing up on our website, NPR.org, or on the Joe's Big Idea page on Facebook. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.
