We know our universe is expanding—this is one of humankind's seminal discoveries. What caused such colossal expansion? We call it the Big Bang, but what were the forces involved? How do they work? What are the implications for understanding the cosmos? And why is the expansion of the universe accelerating? What does this hold for the future?

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Alan Harvey Guth is an American theoretical physicist and cosmologist. He is currently serving as Victor Weisskopf Professor of Physics at the Massachusetts Institute of Technology.

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