The irreversibility of the arrow of time in Space Abstract: In accordance with the law of conservation of momentum, it is shown that the photon at when propagated in outer space, it loses its energy to radiation gravitational waves. With the complete loss of its energy, the photon disappears into the cosmic space. The loss of electromagnetic energy per linear meter is shown. Keywords: arrow of time, the property of a photon to emit gravity, A property of the physical vacuum. The irreversibility of the arrow of time in Space Author: Yanbikov Vildan Shavkyatovich. Volgograd. vildyanyanbikov@yandex.ru Abstract: In accordance with the law of conservation of momentum, it is shown that the photon at when propagated in outer space, it loses its energy to radiation gravitational waves. With the complete loss of its energy, the photon disappears into the cosmic space. The loss of electromagnetic energy per linear meter is shown. Keywords: arrow of time, the property of a photon to emit gravi