It began as Einstein's objection
In 1935 Einstein, author of relativity, published the "EPR paper" with Boris Podolsky and Nathan Rosen. They argued that if quantum mechanics were right, distant particles would influence each other instantly, so the theory had to be incomplete. Einstein mocked the idea as "spooky action at a distance." That same year Schrödinger named the phenomenon entanglement (Verschränkung) and called it the defining trait of quantum mechanics. Einstein believed the particles carried predetermined "hidden variables."
Bell's theorem and the Nobel Prize
For nearly 30 years the question stayed philosophical. In 1964, Northern Irish physicist John Bell turned it into an inequality experiments could test. If hidden variables exist, correlations can't exceed a certain limit, but quantum mechanics predicts they will. Experiments by John Clauser (1972), Alain Aspect (1982), and Anton Zeilinger (from the 1990s) all sided with quantum mechanics, and the three shared the 2022 Nobel Prize in Physics. In 2015, "loophole-free" Bell tests closed the remaining gaps.
Misconceptions and uses
Entanglement correlates outcomes, but you can't choose what the other side sees, so it can't carry faster-than-light messages. That's why it doesn't contradict relativity. Entanglement links qubits in quantum computers. It also underpins quantum cryptography, where eavesdropping breaks the entanglement, and quantum teleportation of states. In 2017 China's Micius satellite distributed entangled photons to ground stations 1,200 km apart.
FAQ
- Can entanglement enable instant communication?
- No. Outcomes can't be controlled, so no information travels faster than light.
- Why did the Nobel take until 2022?
- It took decades to close every experimental loophole and make the conclusion airtight.
Sources reviewed: 2026-10-26
References
- Einstein, A., Podolsky, B., & Rosen, N. (1935). Can quantum-mechanical description of physical reality be considered complete? Phys. Rev., 47, 777–780.
- Bell, J. S. (1964). On the Einstein Podolsky Rosen paradox. Physics, 1(3), 195–200.
- Nobel Prize in Physics 2022: Aspect, Clauser, Zeilinger. NobelPrize.org.