Parallel universes, also known as multiverses, are hypothetical realities that exist alongside our own universe. Each universe may have different laws of physics, histories, or even versions of ourselves. The concept suggests that every decision we make could create a new universe where different choices were made. Scientists explore parallel universes through theories in quantum mechanics and cosmology. For example, the Many-Worlds Interpretation of quantum mechanics proposes that all possible outcomes of a quantum event occur in separate, branching universes. While intriguing, the existence of parallel universes remains a topic of debate and has not been proven.