It all started with a Big Bang. Or maybe it didn’t. In the mid-20th century, most physicists were split on how the universe began — or if it even had a beginning at all. Today, scientists agree that the Big Bang theory best describes the birth of our universe nearly 14 billion years ago.

…“This [debate between theories] was not in the mainstream of physics research,” says David Kaiser, science historian and physics professor at MIT. “Basically no one paid attention or very little attention, even among professional physicists and astronomers.”