Assertion: gamma ray's energy | /r/CapableOf | extend up to a few trillion electron volts
Facets:
value: presently
type: MANNER
Source sentences:
text: There is no theoretical upper limit to the energies of gamma-ray photons and no lower limit to gamma-ray wavelengths; observed energies presently extend up to a few trillion electron volts—these extremely high-energy photons are produced in astronomical sources through currently unidentified mechanisms.