Editing Gravity (section)

===Gravitational lensing===
{{main|Gravitational lensing}}
[[File:Einstein cross.jpg|thumb|upright=0.8|[[Einstein's Cross]], four images of the same distant [[quasar]] around a foreground galaxy due to gravitational lensing]]
Gravity acts on light and matter equally, meaning that a sufficiently massive object could warp light around it and create a gravitational lens. This phenomenon was first confirmed by observation in 1979 using the 2.1 meter telescope at [[Kitt Peak National Observatory]] in Arizona, which saw two mirror images of the same quasar whose light had been bent around the galaxy [[YGKOW G1]].<ref>{{cite book |title=Physics and Astrophysics: Glimpses of the Progress |author1=Subal Kar |edition=illustrated |publisher=CRC Press |year=2022 |isbn=978-1-000-55926-2 |page=106 |url=https://books.google.com/books?id=IWFkEAAAQBAJ}} [https://books.google.com/books?id=IWFkEAAAQBAJ&pg=PT106 Extract of page 106]</ref><ref>{{Cite web |title=Hubble, Hubble, Seeing Double! |url=https://www.nasa.gov/content/goddard/hubble-hubble-seeing-double/#.YpZyvYOZrRl |access-date=31 May 2022 |website=NASA |date=24 January 2014 |archive-date=25 May 2022 |archive-url=https://web.archive.org/web/20220525041837/https://www.nasa.gov/content/goddard/hubble-hubble-seeing-double/#.YpZyvYOZrRl |url-status=live }}</ref>
Many subsequent observations of gravitational lensing provide additional evidence for substantial amounts of dark matter around galaxies. Gravitational lenses do  not focus like [[eyeglass]] lenses, but rather lead to annular shapes called [[Einstein rings]].<ref name="Zee-2013"/>{{rp|370}}