As the Mighty Quasars Flow

Are billions of black holes behind some of the universe’s mysterious energy signals?


Gaze up at the sky on a clear night, far from the city lights, and you might see the moon and some stars, a few planets and maybe even the fuzzy glow of the Milky Way. “In between, there seems to be nothing but emptiness and darkness,” says Xiawei Wang, an astronomy graduate student at Harvard University. “At least that was our view of the cosmos until 50 or so years ago when astronomers realized that space was not as empty as we once thought.”


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