The ΛCDM model, like all models built on the Friedmann–Lemaître–Robertson–Walker metric, assume that the universe looks the same in all directions ([[isotropy]]) and from every ___location ([[homogeneity (physics)|homogeneity]]) if you look aton a large enough scale: "the universe looks the same whoever and wherever you are."<ref>Andrew Liddle. ''An Introduction to Modern Cosmology (2nd ed.).'' London: Wiley, 2003.</ref> This [[cosmological principle]] allows a metric, [[Friedmann–Lemaître–Robertson–Walker metric]], to be derived and developed into a theory to compare to experiments. Without the principle, a metric would need to be extracted from astronomical data, which may not be possible.<ref>{{cite book|title=Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity|author=[[Steven Weinberg]]|isbn=978-0-471-92567-5|year=1972|publisher=John Wiley & Sons, Inc.}}</ref>{{rp|408}} The assumptions were carried over into the ΛCDM model.<ref name="Colin et al">{{cite journal|title=Evidence for anisotropy of cosmic acceleration|author1=Jacques Colin|author2=Roya Mohayaee|author3=Mohamed Rameez|author4=Subir Sarkar|journal=Astronomy and Astrophysics|volume=631|doi=10.1051/0004-6361/201936373|arxiv=1808.04597|date=20 November 2019|pages=L13|bibcode=2019A&A...631L..13C|s2cid=208175643|access-date=25 March 2022|url=https://www.aanda.org/articles/aa/full_html/2019/11/aa36373-19/aa36373-19.html}}</ref> However, some findings suggested violations of the cosmological principle.<ref name="Snowmass21"/><ref name="FLRW breakdown"/>
