Quantum field theory is based on partial differential equations. The properties of a quantum field at any even point depend only on the properties of the fields in its immediate vicinity. Bell's theorem is an indication that quantum mechanics in general is not local.
Welcome to the April 2023 Ask Me Anything episode of Mindscape! These monthly excursions are funded by Patreon supporters (who are also the ones asking the questions). We take questions asked by Patreons, whittle them down to a more manageable number — based primarily on whether I have anything interesting to say about them, not whether the questions themselves are good — and sometimes group them together if they are about a similar topic. Enjoy!