If light propagates in some closed space with a constant radius of curvature R along a circular arc, the distance from the observer z = R·φ must increase with the size of this arc measured by the central angle φ. In order for such a space to maintain its property of constant curvature, it can only expand in all places equally and at some speed dR/dt = ΔV0 >0. For such expansion of space in all places the same, I proposed the name ECSTASY. The observed speed of the objects moving away ΔV will, however, automatically increase with the distance from the observer ΔV= ΔV0·φ.
Such observation is only possible up to the distance from the observer, for which the limit ΔV= c applies, in which c denotes the speed of light propagation to us through space. I called such a boundary a LIGHT BARRIER after the example of a “sound barrier”, which has proven itself, for example, in aviation. In physics, this name probably best corresponds to the so-called cosmological horizon https://en.wikipedia.org/wiki/Cosmological_horizon..
It means that observation beyond this barrier is no longer possible. The emitted light from objects would travel to us at speed c from objects that in our observation would be moving away from us faster than c.