ИСТИНА

Extensive air showers are observing mainly by detections of signals in some surface scintillation detectors or water tanks. These signals are comparing with some estimates calculated in terms of some models of hadron interaction and so some energy estimate is attributing to every shower. Some small fraction of extensive air showers are observed also with the help of telescopes by detection the fluorecence light emitted by nitrogen atoms excited by shower charged particles. As a total number of fluorecence photons is proportional to the energy of the primary particle it is possible to compare this energy with estimates obtained with the surface detectors. If energies of the primary protons are above 30 EeV then due to interactions with cosmic background photons (relic thermal radiation) the energy loses on pi-meson production (Greisen-Zatsepin-Kuzmin effect) will be too high. Thus, these protons can arrive to the Earth only from small distances. Cosmic ray energy spectrum should fall down if real sources of cosmic ray are far away.