John Stewart Bell

John Stewart Bell was a physicist best known for Bell's Theorem, which addresses the foundations of quantum mechanics. His work demonstrated that certain predictions of quantum mechanics conflict with classical intuitions about local realism—essentially the idea that objects have definite properties independent of observation. Bell's Theorem shows that if quantum mechanics is correct, then particles can be instantaneously linked, affecting one another's states over distance, a phenomenon known as "entanglement." This has profound implications for our understanding of reality and has influenced developments in quantum computing and quantum information theory.