Editing Uncertainty principle (section)

=== EPR paradox for entangled particles ===
{{Main|Einstein–Podolsky–Rosen paradox}}
In 1935, Einstein, [[Boris Podolsky]] and [[Nathan Rosen]] published an analysis of spatially separated [[Quantum entanglement|entangled]] particles (EPR paradox).<ref>{{Cite journal |last1=Einstein |first1=A. |last2=Podolsky |first2=B. |last3=Rosen |first3=N. |date=1935-05-15 |title=Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? |journal=Physical Review |volume=47 |issue=10 |pages=777–780 |doi=10.1103/PhysRev.47.777|bibcode=1935PhRv...47..777E |doi-access=free }}</ref> According to EPR, one could measure the position of one of the entangled particles and the momentum of the second particle, and from those measurements deduce the position and momentum of both particles to any precision, violating the uncertainty principle. In order to avoid such possibility, the measurement of one particle must modify the probability distribution of the other particle instantaneously, possibly violating the [[principle of locality]].<ref>{{Cite book |last=Kumar |first=Manjit |title=Quantum: Einstein, Bohr and the great debate about the nature of reality |date=2011 |publisher=Norton |isbn=978-0-393-33988-8 |edition=1st paperback |location=New York}}</ref>

In 1964, [[John Stewart Bell]] showed that this assumption can be falsified, since it would imply a certain [[Bell's theorem|inequality]] between the probabilities of different experiments. [[Bell test|Experimental results]] confirm the predictions of quantum mechanics, ruling out EPR's basic assumption of [[Local hidden-variable theory|local hidden variables]].