Gravitational wave

NASA

“As one great furnace flamed, yet from those flames / No light, but rather darkness visible,” wrote English poet John Milton in Paradise Lost, describing the infernal realm into which the archangel Lucifer fell. Milton’s words could equally describe a more astronomical sort of descent-- the whirling dervish and collision of orbiting black holes, warping the very fabric of space and time around them. Such events are detectable from Earth in the form of gravitational radiation, a phenomenon offering a novel way of seeing the Universe.