Lasers use a light beam to cut away tooth decay before filling cavities, resulting in less vibration and pain than traditional drills, says Barry Jacobson, a pediatric dentist at Mount Sinai Medical Center in New York.

WSJ: To Cut Tooth Decay: A Laser vs. a Drill

The pions, in turn, will decay rapidly into very high-energy light, or gamma rays.

BBC: Cosmic rays: Fermi telescope settles mystery of origin

Meanwhile, the newly real particles decay, giving off (among other things) light, X-rays and gamma rays.

ECONOMIST: Black holes on a desktop: Dumb insolence | The