Quantum Mechanics since its inception has been one of the most philosophically controversial concepts in all of physics. But what really is so confusing about quantum mechanics? The answer lies in two fundamental principles: locality and realism.
Locality – locality asserts that all information and matter in the universe is limited by the speed of light. No experiment has ever contradicted this principle thus far. One may bring up the idea of quantum entanglement with EPR pairs but if you refer to my post on Quantum Teleportation, I discuss how, even in this case, no information can actually be sent faster than the speed of light preserving locality. An interesting visualization of this is the following with light cones.