Today’s Google Doodle honors the late physicist Stephen Hawking on his 80th birthday. Hawking was a renowned cosmologist, and he spent his career theorizing about the origins of the universe, the underlying structure of reality, and the nature of black holes. But he became a household name for the way he communicated those ideas to the public through books and TV appearances.

“My goal is simple,” he once said. “It is a complete understanding of the universe, why it is as it is and why it exists at all.”

One of Hawking’s best-known ideas is that black holes slowly regurgitate information about all the matter they’ve swallowed — but it comes out in a jumbled form called Hawking radiation. In 1974, Hawking proposed that the event horizon of a black hole emits energy. Because energy can be converted into mass, and vice versa (that’s what Albert Einstein’s famous equation E=MC2 tells us), emitting all that energy into space will shrink the black hole. Eventually, it will run out of mass and disappear.

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