What are the theoretical implications of quantum entanglement on the nature of reality, and how does it challenge our classical understanding of space, time, and causality? Begin with what quantum entanglement is and how it defies classical intuitions about locality and separability. Explore how the phenomenon has been tested and confirmed experimentally, then delve into its implications for concepts such as non-locality, superposition, and the measurement problem in quantum mechanics. Consider how entanglement might be linked to the emergence of spacetime in quantum gravity theories, and discuss the potential role of entanglement in resolving the conflict between quantum mechanics and general relativity. Finally, speculate on the philosophical implications of entanglement for our understanding of reality and the nature of existence.