The gravity of a black hole is so strong that not even light can escape it.

黑洞的引力场很强，光也无法逃出。

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Black holes are regions of space so tightly packed with matter that not even light can escape their gravity Wells.

黑洞如同是宇宙中收紧的口袋，在个区域，即使是光线都无法逃出它的重力陷阱。

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These object are so dense that nothing, not even light, escapes once inside a sphere of influence known as an event horizon.

这些东西的密度是那样大，以至于在它们的势力范围——也就是黑洞表面——之内，任何东西，甚至光线，都不能逃离。

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Its event horizon, the outer edge inside which not even light can escape from the black hole's gravitational pull, would be only about 7.5 million kilometres.

BBC: By BBC News Online Science Editor Dr David Whitehouse

Black holes are believed to be so dense that not even light can escape their gravitational pull once it crosses over its theoretical border, known as the event horizon.

CNN: Black holes in a new light

Even so, not even light can escape the clutches of its event horizon its outermost gravitational point of no return where over the eons thousands of stars have likely met their demise.

FORBES: Why Our Galaxy's Supermassive Black Hole Is Hardly The Source For A 2012 Doomsday 'Killshot'