From Jörg Michael
In your article on the true nature of black holes, Lawrence Krauss and others suggest that event horizons may not exist around black holes (6 October, p 36).
Although I am just a “normal” physicist, not an astronomer, I know that light from an object falling into a black hole should become increasingly “stretched out” – red-shifted – and diminish in intensity (from the perspective of an outside observer), as the object approaches the black hole.
So even if there is no “real” event horizon, this won’t matter since infalling objects would still be invisible to anyone watching.
Hannover, Germany
