Certainly, we believe the period is 8, but not -8 years. As for the singularity itself, we know too little about it: we know the laws of physics are denied, the case of infinite density and infinite gravity forces. Penrose and others have convincingly showed that the collapse of a large mass of material inevitably ends with the formation of a singularity, and that, at least in the case of spherically symmetric collapse, surely there is an event horizon that hides this singularity of the external observer. Singularity is a region of space where we know the laws of nature are not satisfied, and therefore we can not predict how things are going there and what their results. If the singularity can be observed directly, ie, if there was a so-called naked singularity, we would lose and those little ability to predict developments in the Universe which are now available to us: progress of our argument would be confused by unpredictable behavior of the singularity.
But since the singularity of “hiding” behind an event horizon, what would they not occurred, it does not affect the located outside the event horizon, the observable universe. If the singularity actually unobservable, then the fact of their existence can be disregarded. Not so clear is the question of whether it required forms event horizon around each of the collapsing body. There is no doubt the formation of this horizon during the collapse of a spherically symmetric mass, resulting in the non-rotating black hole, but collapse of non-spherical or very extended objects sets in this regard, a number of problems. Many scientists share the Penrose hypothesis on the so-called cosmic censorship, according to which the universe is arranged so that the singularities are always formed only within the event horizon, but this conjecture does not yet have a rigorous proof, except for a simple and somewhat idealized case of spherical collapse. Inside a black hole gravity dominates over all other forces, but if the cosmic censorship still exists, then we can never observe the effects of the dominant role of gravity in the extreme point – the central singularity.