  The split property expresses a strong form of independence of spacelike
separated regions in algebraic quantum field theory. In Minkowski spacetime, it
can be proved under hypotheses of nuclearity. An expository account is given of
nuclearity and the split property, and connections are drawn to the theory of
quantum energy inequalities. In addition, a recent proof of the split property
for quantum field theory in curved spacetimes is outlined, emphasising the
essential ideas.
