The article discusses the Boltzmann brain paradox, which is the question of whether our lives and memories are real or just illusions. It explores Ludwig Boltzmann's interpretation of entropy and his application of statistical reasoning to thermodynamics. The paradox arises in an infinitely old universe, where it is more likely for complex structures like brains to form randomly than for our current existence to be real. The resolution to the paradox lies in the Big Bang theory, but contemporary cosmologists still debate the likelihood of Boltzmann brains and their implications for the origin of the universe.