The body of work called quantum field theory is a theory of relativistic quantum mechanics although many aspects of its foundations are difficult to pin down, its a very powerful and useful apparatus.
Special vs general. Quantum field theory is special relativistic and quantum mechanical. The grand unified theory stuff is about uniting general relativity and quantum mechanics.
Nope, it's a thing! The Dirac Equation is one example. It explains the Pauli exclusion principle and predicts anti-matter.
> It is consistent with both the principles of quantum mechanics and the theory of special relativity, and was the first theory to account fully for special relativity in the context of quantum mechanics.
What we don't have is a grand unified theory (a single set of rules that generates both theories), but we can consider relativistic effects in QM theories, and (I assume) vice versa.
