John Learned ’61

Not everyone can say they’ve spent their career hunting for ghosts. But John Learned ’61 might just be one of the few who can.

Learned, a physicist and a professor at the University of Hawaii at Mānoa, has worked to uncover the secrets of neutrinos, also called “ghost particles,” throughout his decades-long career. These shy, imperceptibly small particles constantly bombard Earth from outer space but hardly ever bump into matter, making them hard to detect. Learned has worked on experiments with the goal of detecting neutrinos as they fly down to our planet, contributing to early research papers that went on to win Nobel Prizes in Physics in 2002 and 2015.

In 2023, his work earned him the prestigious Yodh Prize, awarded to researchers who have contributed to our understanding of cosmic rays. Learned helped pioneer the field of cosmic neutrino astronomy, which tries to make sense of the universe’s fundamental structure by studying the neutrinos that travel to Earth from across outer space.

As a prize recipient, Learned was invited to give a lecture at UC Irvine on his research and was awarded $2,000.

“I’ve had various honors in my lifetime, but this was beyond anything I had experienced,” he says. “It was very humbling.” The recognition, though, has not altered his desire to keep contributing to the daily grind of data gathering. He travels to take shifts on experiments based in Japan, where massive detectors are used to record any trace of a neutrino so researchers can pinpoint where it might have originated. But because neutrino interactions are infrequent, Learned says, most of his shifts are spent making sure the equipment is functioning properly. Still, the possibility of being there for the arrival of a burst of ghostly neutrinos keeps the work interesting.

“That’s one of the more exciting things,” Learned says. “When you’re watching this in real time, thinking that you could be the one sitting there when the event of the century takes place.”

— Emily Dreihaus