Comment on ``Velocity at the Schwarzschild Horizon Revisited'' by I. Tereno

Abstract

In a recent preprint (astro-ph/9905144) Tereno has tried to find the physical 3-velocity (V) at the Event Horizon of a Kruskal Black Hole. This has been done in the backdrop of the recent work by Mitra (astro-ph/9904162) where it was shown that the radial geodesic of material particle, unphysically, becomes null at the Event Horizon. Although Tereno stops short of finding the precise value of V at r=2M, he concludes that V <1. It is pointed out with reference to Eq.(13) of Tereno's work that since his delta = (r -2M)/r tends to 0 as r tends to 2M, V indeed tends to 1. It appears that Tereno's conclusion is driven by his inability to conceive proper limiting value of fractions. Similarly, his idea that, the velocity addition formula of Sp. Theory of Relativity breaks down when both the velocities approach unity is due his same inability. In particular, our central result that Schwarschild BHs must have M=0 has been obtained independently from three different considerations (gr-qc/9810038, astro-ph/9904162, 163). And we also offer here the essential physical reason why the speed of free fall at the Event Horizon must be equal to the speed of light in coordinate system. Yet we are thankful to Tereno for making the first attempt to scientifically criticize our relevant work.