Many widely held science “facts” are actually outdated myths or outright falsehoods that persist thanks to repetition, media oversimplification, and our own cognitive biases. Despite overwhelming scientific evidence debunking these misconceptions, they continue to spread in classrooms, everyday conversations, and pop culture. From misunderstandings about the human brain to myths about animal behavior and the laws of physics, these beliefs linger stubbornly. Their persistence shows why scientific literacy and critical thinking are more important than ever. Let’s set the record straight on 23 “facts” everyone thinks they know—but are actually complete nonsense.