The Relationship Between Quantum Mechanics and Special Relativity

Anti-matter and antiparticles somehow make quantum mechanics and special relativity work together. What does that mean? So it all has to do with preserving causality. And special relativity makes it really hard to think about causality, to think about the order that things happen in the universe. Because it forces us to thinking about the order of events in a very different way than like Newton thought about things.