Editing Erwin Schrödinger (section)

===Quantum mechanics===

====New quantum theory====
In the first years of his career, Schrödinger became acquainted with the ideas of the [[old quantum theory]], developed in the works of Einstein, [[Max Planck]], [[Niels Bohr]], [[Arnold Sommerfeld]], and others. This knowledge helped him work on some problems in [[theoretical physics]], but the Austrian scientist at the time was not yet ready to part with the traditional methods of [[classical physics]].<ref>{{Cite journal |last=Fischer |first=Earnst Peter |date=Autumn 1984 |title=We Are All Aspects of One Single Being: An Introduction to Erwin Schrödinger |url=https://www.jstor.org/stable/40970963 |journal=Social Research |publisher=The Johns Hopkins University Press |volume=51 |issue=3 |pages=809–835 |jstor=40970963 |pmid=11616408 |via=JSTORE |jstor-access= |access-date=6 February 2024 |archive-date=6 February 2024 |archive-url=https://web.archive.org/web/20240206162904/https://www.jstor.org/stable/40970963 |url-status=live }}</ref>

Schrödinger's first publications about atomic theory and the theory of spectra began to emerge only from the beginning of the 1920s, after his personal acquaintance with Sommerfeld and [[Wolfgang Pauli]] and his move to Germany. In January 1921, Schrödinger finished his first article on this subject, about the framework of the [[Bohr-Sommerfeld quantization|Bohr–Sommerfeld quantization]] of the interaction of electrons on some features of the spectra of the alkali metals. Of particular interest to him was the introduction of relativistic considerations in quantum theory. In autumn 1922, he analyzed the electron orbits in an atom from a geometric point of view, using methods developed by his friend [[Hermann Weyl]]. This work, in which it was shown that quantum orbits are associated with certain geometric properties, was an important step in predicting some of the features of wave mechanics. Earlier in the same year, he created the Schrödinger equation of the [[relativistic Doppler effect]] for spectral lines, based on the hypothesis of light quanta and considerations of energy and momentum. He liked the idea of his teacher Exner on the statistical nature of the conservation laws, so he enthusiastically embraced the [[BKS theory]] of Bohr, [[Hans Kramers]], and [[John C. Slater]], which suggested the possibility of violation of these laws in individual atomic processes (for example, in the process of emission of radiation). Although the [[Bothe–Geiger coincidence experiment]] soon cast doubt on this, the idea of energy as a statistical concept was a lifelong attraction for Schrödinger, and he discussed it in some reports and publications.<ref name=jammer>{{cite book|first=Max |last=Jammer |author-link=Max Jammer |title=The Conceptual Development of Quantum Mechanics |location=New York |publisher=American Institute of Physics |orig-year=1966 |year=1989 |isbn=978-0-88318-617-6 |oclc=300417620}}</ref>

====Creation of wave mechanics====
In January 1926, Schrödinger published in ''[[Annalen der Physik]]'' the paper "{{Lang|de|Quantisierung als Eigenwertproblem}}" (Quantization as an [[Eigenvalue]] Problem)<ref>{{cite journal|last=Schrodinger|first=Erwin|title=Quantisierung als Eigenwertproblem|journal=[[Annalen der Physik]]|year=1926|volume=384|issue=4|pages=273–376|doi=10.1002/andp.19263840404|bibcode=1926AnP...384..361S|doi-access=}}</ref> on wave mechanics and presented what is now known as the Schrödinger equation. In this paper, he gave a "derivation" of the wave equation for time-independent systems and showed that it gave the correct energy eigenvalues for a hydrogen-like atom. This paper has been universally celebrated as one of the most important achievements of the twentieth century and created a revolution in most areas of quantum mechanics and indeed of all physics and chemistry. A second paper was submitted just four weeks later that solved the [[quantum harmonic oscillator]], [[rigid rotor]], and [[diatomic molecule]] problems and gave a new derivation of the Schrödinger equation. A third paper, published in May, showed the equivalence of his approach to that of [[Werner Heisenberg]]'s [[matrix mechanics]] and gave the treatment of the [[Stark effect]]. A fourth paper in this series showed how to treat problems in which the system changes with time, as in scattering problems. In this paper, he introduced a complex solution to the wave equation in order to prevent the occurrence of fourth- and sixth-order differential equations. Schrödinger ultimately reduced the order of the equation to one.<ref>''[[The Dreams That Stuff Is Made Of]]: The Most Astounding Papers of Quantum Physics—and How They Shook the Scientific World'', [[Stephen Hawking]], (editor), the papers by Schrödinger.</ref>

Building on a paper by Einstein, [[Boris Podolsky]], and [[Nathan Rosen]], which introduced the thought-experiment now known as the [[EPR paradox]], Schrödinger published in 1935 a paper that codified the concept of [[quantum entanglement]].<ref name="Schroeder-2017">{{cite journal |last=Schroeder |first=Daniel V. |date=1 November 2017 |title=Entanglement isn't just for spin |url=https://pubs.aip.org/ajp/article/85/11/812/1057936/Entanglement-isn-t-just-for-spin |journal=American Journal of Physics |volume=85 |issue=11 |pages=812–820 |arxiv=1703.10620 |doi=10.1119/1.5003808 |bibcode=2017AmJPh..85..812S }}</ref> He deemed this quantum phenomenon "the one that enforces its entire departure from [[Classical mechanics|classical]] lines of thought."<ref name="Schrödinger1935">{{cite journal |author=Schrödinger |first=Erwin |year=1935 |title=Discussion of probability relations between separated systems |journal=Mathematical Proceedings of the Cambridge Philosophical Society |volume=31 |issue=4 |pages=555–563 |bibcode=1935PCPS...31..555S |doi=10.1017/S0305004100013554}}</ref>

Schrödinger was not entirely comfortable with the implications of quantum theory referring to his theory as "wave mechanics".<ref>Beller, Mara. "Matrix Theory before Schrodinger: Philosophy, Problems, Consequences." Isis, vol. 74, no. 4, [The University of Chicago Press, The History of Science Society], 1983, pp. 469–91, http://www.jstor.org/stable/232208 {{Webarchive|url=https://web.archive.org/web/20211006103703/https://www.jstor.org/stable/232208 |date=6 October 2021 }}. "The Gottingen-Copenhagen physicists, however, presented a united front. They cooperated intimately, each contributing extensively to the emergence of the new philosophy. The distribution of talents in the Gottingen-Copenhagen group could not have been better. The youthful vigor and brilliance of Heisenberg, together with the mathematical virtuosity of Dirac, Jordan, and Born, were balanced by Bohr's philosophical profundity and Pauli's penetrating critical mind."</ref><ref>Stone, A. Douglas (2013). "Confusion and Then Uncertainty." ''Einstein and the Quantum: The Quest of the Valiant Swabian''. Princeton University Press, pp. 268–78, http://www.jstor.org/stable/j.ctt3fgxvv.32."Ironically, Schrödinger was correct; his method was much more intuitive and visualizable than that of Heisenberg and Born, and it has become the overwhelmingly preferred method for presenting the subject. But with Born's probabilistic interpretation of the wave-function, Heisenberg's uncertainty principle, and Bohr's mysterious complementarity principle, the 'Copenhagen interpretation' reigned supreme, and the term 'wave mechanics' disappeared; it was all quantum mechanics."</ref> He wrote about the probability interpretation of quantum mechanics, saying, "I don't like it, and I'm sorry I ever had anything to do with it." (In order to ridicule the [[Copenhagen interpretation|viewpoints of Bohr and Heisenberg]] on quantum mechanics, he contrived the famous thought experiment called the [[Schrödinger's cat]] paradox.<ref>{{cite news |url=https://www.nytimes.com/2005/12/26/science/a-quantum-sampler.html |work=The New York Times |title=A Quantum Sampler |date=26 December 2005 |access-date=13 August 2021 |archive-date=15 September 2017 |archive-url=https://web.archive.org/web/20170915080006/http://www.nytimes.com/2005/12/26/science/a-quantum-sampler.html |url-status=live }}</ref> He was said to have angrily complained to his students that "''now the damned Göttingen physicists use my beautiful wave mechanics for calculating their shitty matrix elements.''"<ref>[[Helmut Rechenberg|Rechenberg, Helmut]]. "Werner Heisenberg: Die Sprache der Atome" Springer-Verlag, 2010, pp. 485, https://link.springer.com/book/10.1007/978-3-540-69222-5 {{Webarchive|url=https://web.archive.org/web/20220528034502/https://link.springer.com/book/10.1007/978-3-540-69222-5 |date=28 May 2022 }}. "Noch drastischer sollte Schrödinger seine Meinung im Züricher Seminar nach einem Vortrag über eine neue Arbeit der Konkurrenten ausgedrückt haben. Er setzte sich nachher leicht verzweifelt und verärgert auf die Straße und sagte: "''Jetzt benützen die verdammten Göttinger meine schöne Wellenmechanik zur Ausrechnung ihrer Scheiß-Matrixelemente.''"</ref>)

====Work on a unified field theory====
Following his work on quantum mechanics, Schrödinger devoted considerable effort to working on a [[unified field theory]] that would unite [[gravity]], [[electromagnetism]], and nuclear forces within the basic framework of [[general relativity]], doing the work with an extended correspondence with Albert Einstein.<ref name="Halpern">{{Cite web |last=Halpern |first=Paul |date=2015-04-01 |title=Battle of the Nobel Laureates |url=https://medium.com/starts-with-a-bang/battle-of-the-nobel-laureates-712d444610d3 |access-date=2023-10-13 |website=Starts With A Bang! |language=en |archive-date=7 November 2017 |archive-url=https://web.archive.org/web/20171107011418/https://medium.com/starts-with-a-bang/battle-of-the-nobel-laureates-712d444610d3 |url-status=live }}</ref> In 1947, he announced a result, "Affine Field Theory",<ref>Schrödinger, E., ''Proceedings of the Royal Irish Academy'', Vol. 51A (1947), [http://einstein-schrodinger.com/schrodingerI.html pp. 163–171] {{Webarchive|url=https://web.archive.org/web/20150406052716/http://einstein-schrodinger.com/schrodingerI.html |date=6 April 2015 }}. (accessed 3 November 2017)</ref> in a talk at the Royal Irish Academy, but the announcement was criticized by Einstein as "preliminary" and failed to lead to the desired unified theory.<ref name="Halpern" /> Following the failure of his attempt at unification, Schrödinger gave up his work on unification and turned to other topics. Additionally, Schrödinger reportedly never collaborated with a major physicist for the remainder of his career.<ref name="Halpern" />