What is realism and how can it be non-local?

TL;DR

This paper examines the concept of realism in quantum mechanics, highlighting the challenges of non-local hidden variables and their incompatibility with special relativity.

Contribution

It demonstrates that non-local hidden variables face fundamental issues and are incompatible with the principles of special relativity.

Findings

Non-local hidden variables are problematic.

Non-local hidden variables conflict with special relativity.

Local hidden variables cannot explain quantum entanglement.

Abstract

The concept of realism in quantum mechanics means that results of measurement are caused by physical variables, hidden or observable. Local hidden variables were proved unable to explain results of measurements on entangled particles tested far away from one another. Then, some physicists embraced the idea of nonlocal hidden variables. The present article proves that this idea is problematic, that it runs into an impasse vis-\`a-vis the special relativity.