Never before have astrophysicists measured light of such high energy from a celestial object so far away. Around 7 billion years ago, a huge explosion occurred at the black hole in the center of a galaxy. This was followed by a burst of high-intensity gamma rays. A number of telescopes have succeeded in capturing this light. An added bonus: it was thus possible to reconfirm Einstein’s General Theory of Relativity, as the light rays encountered a less distant galaxy en route to Earth — and were deflected by this so-called gravitational lens.