Editing Copernican principle (section)

==Tests of the principle==
The Copernican principle has never been proven, and in the most general sense cannot be proven, but it is implicit in many modern theories of physics. Cosmological models are often derived with reference to the [[cosmological principle]], slightly more general than the Copernican principle, and many tests of these models can be considered tests of the Copernican principle.<ref name=clarkson>{{Cite journal |last1=Clarkson |first1=C. |last2=Bassett |first2=B. |last3=Lu |first3=T. |title=A General Test of the Copernican Principle |doi=10.1103/PhysRevLett.101.011301 |journal=Physical Review Letters |volume=101 |issue=1 |page=011301 |year=2008 |pmid=18764099 |arxiv=0712.3457 |bibcode=2008PhRvL.101a1301C |s2cid=32735465 }}</ref>

===Historical===
Before the term Copernican principle was even coined, past assumptions, such as [[geocentrism]], [[heliocentrism]], and [[galactocentrism]], which state that Earth, the Solar System, or the Milky Way respectively were located at the center of the universe, were shown to be false. The [[Copernican Revolution]] dethroned Earth to just one of many planets orbiting the Sun. [[Proper motion]] was mentioned by Halley. [[William Herschel]] found that the Solar System is moving through space within our disk-shaped [[Milky Way]] galaxy. [[Edwin Hubble]] showed that the Milky Way galaxy is just one of many galaxies in the universe. Examination of the galaxy's position and motion in the universe led to the [[Big Bang|Big Bang theory]] and the whole of modern [[cosmology]].

===Modern tests===
Recent and planned tests relevant to the cosmological and Copernican principles include:
* time drift of cosmological redshifts;<ref name=uzan>{{Cite journal |last1=Uzan |first1=J. P. |last2=Clarkson |first2=C. |last3=Ellis |first3=G. |title=Time Drift of Cosmological Redshifts as a Test of the Copernican Principle |doi=10.1103/PhysRevLett.100.191303 |journal=Physical Review Letters |volume=100 |issue=19 |page=191303 |year=2008 |pmid=18518435 |arxiv=0801.0068 |bibcode=2008PhRvL.100s1303U |s2cid=31455609}}</ref>
* modelling the local gravitational potential using reflection of [[cosmic microwave background]] (CMB) photons;<ref name=caldwell>{{Cite journal |last1=Caldwell |first1=R. |last2=Stebbins |first2=A. |doi=10.1103/PhysRevLett.100.191302 |title=A Test of the Copernican Principle |journal=Physical Review Letters |volume=100 |issue=19 |page=191302 |year=2008 |pmid=18518434 |arxiv=0711.3459 |bibcode=2008PhRvL.100s1302C |s2cid=5468549}}</ref>
* the [[redshift]] dependence of the luminosity of [[supernovae]];<ref name=clifton>{{Cite journal |last1=Clifton |first1=T. |last2=Ferreira |first2=P. |last3=Land |first3=K. |title=Living in a Void: Testing the Copernican Principle with Distant Supernovae |doi=10.1103/PhysRevLett.101.131302 |journal=Physical Review Letters |volume=101 |issue=13 |year=2008 |pmid=18851434 |arxiv=0807.1443 |bibcode=2008PhRvL.101m1302C |page=131302 |s2cid=17421918}}</ref>
* the kinetic [[Sunyaev–Zeldovich effect]] in relation to dark energy;<ref name=zhang>{{Cite journal |last1=Zhang |first1=P. |last2=Stebbins |first2=A. |doi=10.1098/rsta.2011.0294 |title=Confirmation of the Copernican principle through the anisotropic kinetic Sunyaev Zel'dovich effect |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |volume=369 |issue=1957 |pages=5138–5145 |year=2011 |pmid=22084299 |bibcode=2011RSPTA.369.5138Z |doi-access=free }}</ref>
* [[cosmic neutrino background]];<ref name=jia>{{Cite journal |last1=Jia |first1=J. |last2=Zhang |first2=H. |doi=10.1088/1475-7516/2008/12/002 |title=Can the Copernican principle be tested using the cosmic neutrino background? |journal=Journal of Cosmology and Astroparticle Physics |volume=2008 |issue=12 |page=002 |year=2008 |arxiv=0809.2597 |bibcode=2008JCAP...12..002J |s2cid=14320348}}</ref>
* the integrated [[Sachs–Wolfe effect]];<ref name=tomita>{{Cite journal |last1=Tomita |first1=K. |last2=Inoue |first2=K. |doi=10.1103/PhysRevD.79.103505 |title=Probing violation of the Copernican principle via the integrated Sachs–Wolfe effect |journal=Physical Review D |volume=79 |issue=10 |page=103505 |year=2009 |arxiv=0903.1541 |bibcode=2009PhRvD..79j3505T |s2cid=118478786}}</ref>
* testing the isotropy and homogeneity of the CMB;<ref name=bull>{{Cite journal |last1=Clifton |first1=T. |last2=Clarkson |first2=C. |last3=Bull |first3=P. |title=Isotropic Blackbody Cosmic Microwave Background Radiation as Evidence for a Homogeneous Universe |doi=10.1103/PhysRevLett.109.051303 |journal=Physical Review Letters |volume=109 |issue=5 |year=2012 |pmid=23006164 |arxiv=1111.3794 |bibcode=2012PhRvL.109e1303C |page=051303 |s2cid=119278505}}</ref><ref name=kim>{{Cite journal |last1=Kim |first1=J. |last2=Naselsky |first2=P. |doi=10.1088/0004-637X/739/2/79 |title=Lack of Angular Correlation and Odd-Parity Preference in Cosmic Microwave Background Data |journal=The Astrophysical Journal |volume=739 |issue=2 |page=79 |year=2011 |arxiv=1011.0377 |bibcode=2011ApJ...739...79K |s2cid=118580902}}</ref><ref name=copi>{{Cite journal |last1=Copi |first1=C. J. |last2=Huterer |first2=D. |last3=Schwarz |first3=D. J. |last4=Starkman |first4=G. D. |title=Large-Angle Anomalies in the CMB |doi=10.1155/2010/847541 |journal=Advances in Astronomy |volume=2010 |pages=1–17 |year=2010 |arxiv=1004.5602 |bibcode=2010AdAst2010E..92C |s2cid=13823900 |doi-access=free}}</ref><ref name=planck>{{cite journal |arxiv=1303.5083 |collaboration=Planck Collaboration |last=Ade |title=Planck 2013 results. XXIII. Isotropy and Statistics of the CMB |year=2013 |doi=10.1051/0004-6361/201321534 |volume=571 |journal=Astronomy & Astrophysics |page=A23 |bibcode=2014A&A...571A..23P |s2cid=13037411}}</ref><ref name="longo">{{cite arXiv |eprint=astro-ph/0703325 |last=Longo |first=Michael |title=Does the Universe Have a Handedness? |year=2007}}</ref>
* observation of the [[KBC Void]] – some authors claim it violates the [[cosmological principle]] and thus the Copernican principle,<ref name="Haslbauer">{{Cite journal |last1=Haslbauer |first1=M. |last2=Banik |first2=I. |last3=Kroupa |first3=P. |date=2020-12-21 |title=The KBC void and Hubble tension contradict LCDM on a Gpc scale – Milgromian dynamics as a possible solution |journal=Monthly Notices of the Royal Astronomical Society |volume=499 |issue=2 |pages=2845–2883 |arxiv=2009.11292 |bibcode=2020MNRAS.499.2845H |doi=10.1093/mnras/staa2348 |issn=0035-8711 |doi-access=free}}</ref> while others claim that it is consistent with them.<ref>{{Cite journal |last1=Sahlén |first1=Martin |last2=Zubeldía |first2=Íñigo |last3=Silk |first3=Joseph |date=2016 |title=Cluster–Void Degeneracy Breaking: Dark Energy, Planck, and the Largest Cluster and Void |journal=The Astrophysical Journal Letters |volume=820 |issue=1 |pages=L7 |doi=10.3847/2041-8205/820/1/L7 |issn=2041-8205 |arxiv=1511.04075 |bibcode=2016ApJ...820L...7S |s2cid=119286482 |doi-access=free }}</ref>