What Is the Big Bang Theory? | Explained in Under 10 Minutes

13.8 billion years ago, everything that exists — all matter, all energy, space itself — was compressed into a volume smaller than a proton. Then it began expanding. Neev opens there, and Lewis immediately stops her: "Space itself began expanding" — expanding into what, exactly? Emma's answer is honest. Into nothing. There is no outside. Human brains evolved to throw spears and spot predators. We're not built to intuitively grasp the expansion of spacetime. But we can understand the evidence.The evidence is remarkable. Emma walks through Edwin Hubble's 1920s discovery that almost every galaxy is moving away from us — the further away, the faster. Wind that back and everything converges. Lewis tells the story of two Bell Labs engineers in 1965 who kept picking up a faint hiss from every direction and blamed pigeon droppings. They cleaned the antenna. They relocated the pigeons. The hiss remained. It was the oldest light in the universe — the afterglow of creation. Nobel Prize, 1978.Neev closes with scale. The hydrogen in the water you're drinking right now was forged in the first three minutes of the universe's existence. Every hydrogen atom in your body is 13.8 billion years old. And the ultimate fate? Dark energy keeps accelerating expansion until galaxies recede beyond the reach of light, stars exhaust their fuel, black holes evaporate. Heat death. Maximum entropy. An endless, final quiet. Lewis: "That's the most peaceful-sounding apocalypse I've ever heard."If you enjoyed this episode, please subscribe — and send your topic suggestions to [email protected]. We read every one.