If we consider the observed distance **z** from us according to the model of curved space with a constant radius of curvature **R** as measured along the arc **z = R·φ**, where **φ** is the central angle of this arc, then for a closed circle we cannot consider any observed element as more distant than half of the circle for **φ=π**. And we call such a distance the **SIZE of UNIVERSE** and denote it as **Rv****= R·π**. Because any observed object for **φ>π** would actually already be observed in the opposite direction for **φ<π**. However, we cannot include such an object in the Universe twice, because it cannot even be in the Universe twice.

But we also called the expansion of curved space with a constant radius of curvature **R**, which expansion is the same in all places, as **ECSTASY** of space. If we consider this expansion as if at a constant speed **dR/dt =** **ΔV**_{0} **>0**, then not only the observed distance **z = R·φ** but also the observed speed of receding **ΔV****=** **ΔV**_{0}**·φ** must appear to us as linearly increasing with the central angle** φ** measured from us. And we called the limit of such an increase in the observed speed, when **ΔV****=c** and where **c** is the speed of light, as the **LIGHT BARRIER** of the Universe **SB**_{V}, beyond which we can no longer observe the Universe.

And to this LIGHT BARRIER we also assigned the time term **AGE of UNIVERSE** **Vv** assuming that light spread to us along the entire path at a constant speed **c**. It is therefore such a time interval during which the Universe expanded by ECSTASY, up to a size that I will distinguish by the name **Observable SIZE of UNIVERSE** **RPv****= ****ΔV**_{0}**•Vv**.