### 6.1 Relevance of astrophysical observations

Terrestrial experiments are invariably concerned with low energy processes. They are therefore best
suited for looking at the mSME, which involves lower dimension operators. Astrophysics is more suited for
directly constraining higher dimension operators as the Lorentz violating effects scale with energy. As
mentioned in Section 4.3, the existence of Lorentz violating higher dimensional operators would generically
generate lower dimension ones. At the level of sensitivity of astrophysical tests, the size of the
corresponding lower dimension operators should give signals in terrestrial experiments. Hence,
if a signal is seen in astrophysics for Lorentz violation, one must then explain why Lorentz
invariance passes all the low energy tests. As mentioned in Section 4.3, exact SUSY, which is
the only known mechanism to completely protect lower dimension operators, yields dispersion
modifications (the primary method used in astrophysics) that are unobservable. In summary there is
currently no “natural” and complete way that astrophysics might observe Lorentz violation, but
terrestrial experiments confirm Lorentz invariance. That said, physics is often surprising, and it
is therefore still important to check for Lorentz violating signals in all possible observational
areas.