The phenomena of the microwave induced zero resistance states (MIZRS) and the microwave induced resistance oscillations (MIRO) were discovered in the ultraclean two-dimensional electron systems in 2001 -- 2003 and have attracted great interest of researchers. In spite of numerous theoretical efforts the true origin of these effects remains unknown so far. We show that the MIRO/ZRS phenomena are naturally explained by the influence of the ponderomotive forces which arise in the near-contact

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... ns of the two-dimensional electron gas under the action of microwaves. The proposed analytical theory is in agreement with all experimental facts accumulated so far and provides a simple and self-evident explanation of the microwave frequency, polarization, magnetic field, mobility, power and temperature dependencies of the observed effects.