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Can math.atan2 return INF?


Marko Rauhamaa wrote:
> We cannot get any information on black holes proper because black holes
> cannot come into existence according to the very theory that predicts
> black holes. It will take infinitely long for an event horizon to form.

Only in some frames of reference.

By your reasoning, Zeno's paradox proves that a runner
can never reach the finish line in a race. But it really
only proves that if you measure time in such a way that
the finishing time is infinitely far in your future, you
will never see him finish.

That's obviously a screwy way to measure time in a
race, but something similar is happening with the black
hole. If you draw coordinate lines in a particular
way (corresponding to the inertial frame of an outside
observer stationary with respect to the hole) then
the time axis bends in such a way that it never
crosses the horizon.

But there's no reason you have to draw the coordinates
that way; there are plenty of others in which the time
axis does cross the horizon.

-- 
Greg