Editing Doubly special relativity (section)

==Predictions==
{{see also|Modern searches for Lorentz violation}}

Experiments to date have not observed contradictions to Special Relativity.

It was initially speculated that ordinary special relativity and doubly special relativity would make distinct physical predictions in high-energy processes and, in particular, the derivation of the [[Greisen–Zatsepin–Kuzmin limit|GZK limit]] on energies of [[cosmic ray]]s from distant sources would not be valid. However, it is now established that standard doubly special relativity does not predict any suppression of the GZK cutoff, contrary to the models where an [[preferred frame|absolute local rest frame]] exists, such as [[effective field theory|effective field theories]] like the [[Standard-Model Extension]].

Since DSR generically (though not necessarily) implies an energy-dependence of the speed of light, it has further been predicted that, if there are modifications to first order in energy over the Planck mass, this energy-dependence would be observable in high energetic [[photon]]s reaching Earth from distant [[gamma ray burst]]s. Depending on whether the now energy-dependent speed of light increases or decreases with energy (a model-dependent feature), highly energetic photons would be faster or slower than the lower energetic ones.<ref name="Smolin2009">
{{Cite journal |last1=Amelino-Camelia |first1=Giovanni |last2=Smolin |first2=Lee |year=2009 |title=Prospects for constraining quantum gravity dispersion with near term observations |journal=[[Physical Review D]] |volume=80 |issue=8 |pages=084017 |arxiv=0906.3731 |bibcode=2009PhRvD..80h4017A |doi=10.1103/PhysRevD.80.084017 |s2cid=9533538}}</ref> However, the [[Fermi Gamma-ray Space Telescope|Fermi-LAT]] experiment in 2009 measured a 31&nbsp;GeV photon, which nearly simultaneously arrived with other photons from the same burst, which excluded such dispersion effects even above the Planck energy.<ref name=lat>{{cite journal |author=Fermi LAT Collaboration|title=A limit on the variation of the speed of light arising from quantum gravity effects|journal=Nature|volume=462|issue=7271 |year=2009|pages=331–334|doi=10.1038/nature08574|arxiv=0908.1832|pmid=19865083
|bibcode = 2009Natur.462..331A |s2cid=205218977}}</ref> Moreover, it has been argued that DSR, with an energy-dependent speed of light, is inconsistent and first order effects are ruled out already because they would lead to non-local particle interactions that would long have been observed in particle physics experiments.<ref name="Hossenfelder2009">
{{cite arXiv
 |first=S. |last=Hossenfelder
 |title=The Box-Problem in Deformed Special Relativity
 |year=2009
 |eprint=0912.0090
|class=gr-qc
 }}</ref>