Gamma rays are like cheetahs: they are the charismatic megafauna of the particle world. They are light of the maximum possible potency, usually defined as a wavelength shorter than 10–11 meter—a realm where light’s wave nature is hard to observe and its particulate nature stands out. Each gamma photon has an energy of more than 100 kilo-electron-volts (keV), 100,000 times more than a photon of visible light. The mightiest gamma ever recorded packed a punch of 100 tera-electron-volts (TeV), far outgunning anything particle physicists can blast out with their most powerful instrument, the Large Hadron Collider.