It is believed that one of the main arguments from which the conclusion about the accelerated expansion of the Universe follows is the reduced brightness of distant supernovae. A mathematical study of this phenomenon unexpectedly led to the exact opposite conclusion. If distant supernovae are visible dimmer, then the Universe is expanding at a slower rate. It is believed that one of the main arguments from which the conclusion about the accelerated expansion of the Universe follows is the reduced brightness of distant supernovae. A mathematical study of this phenomenon unexpectedly led to the exact opposite conclusion. If distant supernovae are seen dimmer, then the universe is expanding decelerate.