Editing Hidden-variable theory (section)

=== Early attempts at hidden-variable theories ===
Shortly after making his famous "God does not play dice" comment, Einstein attempted to formulate a deterministic counter proposal to quantum mechanics, presenting a paper at a meeting of the [[Prussian Academy of Sciences|Academy of Sciences]] in Berlin, on 5 May 1927, titled "Bestimmt Schrödinger's Wellenmechanik die Bewegung eines Systems vollständig oder nur im Sinne der Statistik?" ("Does Schrödinger's wave mechanics determine the motion of a system completely or only in the statistical sense?").<ref>[https://einsteinpapers.press.princeton.edu/vol15-trans/546 The Collected Papers of Albert Einstein, Volume 15: The Berlin Years: Writings & Correspondence, June 1925-May 1927 (English Translation Supplement), p. 512]</ref><ref>[http://alberteinstein.info/vufind1/Record/EAR000034338 Albert Einstein Archives] reel 2, item 100</ref>  However, as the paper was being prepared for publication in the academy's journal, Einstein decided to withdraw it, possibly because he discovered that, contrary to his intention, his use of Schrödinger's field to guide localized particles allowed just the kind of non-local influences he intended to avoid.<ref>{{cite book |last=Baggott |first=Jim |year=2011 |title=The Quantum Story: A History in 40 Moments |url=https://archive.org/details/quantumstoryhist00bagg |url-access=limited |location=New York |publisher=Oxford University Press |pages=[https://archive.org/details/quantumstoryhist00bagg/page/n136 116]–117|isbn=978-0-19-956684-6 }}</ref>

At the [[Solvay Conference#Fifth Conference|Fifth Solvay Congress]], held in Belgium in October 1927 and attended by all the major theoretical physicists of the era, [[Louis de Broglie]] presented [[Pilot wave theory|his own version of a deterministic hidden-variable theory]], apparently unaware of Einstein's aborted attempt earlier in the year. In his theory, every particle had an associated, hidden "pilot wave" which served to guide its trajectory through space. The theory was subject to criticism at the Congress, particularly by [[Wolfgang Pauli]], which de Broglie did not adequately answer; de Broglie abandoned the theory shortly thereafter.