Editing Doppler effect (section)

==Inverse Doppler effect==
Since 1968 scientists such as [[Victor Veselago]] have speculated about the possibility of an inverse Doppler effect. The size of the Doppler shift depends on the refractive index of the medium a wave is traveling through. Some materials are capable of [[negative refraction]], which should lead to a Doppler shift that works in a direction opposite that of a conventional Doppler shift.<ref>{{cite web|url=https://physicsworld.com/a/doppler-shift-is-seen-in-reverse/|title=Doppler shift is seen in reverse|date=10 March 2011|website=Physics World}}</ref> The first experiment that detected this effect was conducted by Nigel Seddon and Trevor Bearpark in [[Bristol]], [[United Kingdom]] in 2003.<ref group=p>{{cite journal |last1=Kozyrev |first1=Alexander B. |last2=van der Weide |first2=Daniel W. |title=Explanation of the Inverse Doppler Effect Observed in Nonlinear Transmission Lines |journal=Physical Review Letters |volume=94 |issue=20 |pages=203902 |year=2005 |pmid=16090248 |doi=10.1103/PhysRevLett.94.203902 |bibcode=2005PhRvL..94t3902K}}</ref> Later, the inverse Doppler effect was observed in some inhomogeneous materials, and predicted inside a Vavilov–Cherenkov cone.<ref>{{Cite journal| last1=Shi|first1=Xihang | last2=Lin|first2=Xiao| last3=Kaminer|first3=Ido |last4=Gao|first4=Fei |last5=Yang|first5=Zhaoju|last6=Joannopoulos|first6=John D.|last7=Soljačić|first7=Marin| last8=Zhang |first8=Baile |date=October 2018|title=Superlight inverse Doppler effect|journal=Nature Physics|volume=14|issue=10| pages=1001–1005| doi=10.1038/s41567-018-0209-6|issn=1745-2473|arxiv=1805.12427|bibcode=2018NatPh..14.1001S|s2cid=125790662}}</ref>