Can math.atan2 return INF?
Gregory Ewing <greg.ewing at canterbury.ac.nz>:
> Marko Rauhamaa wrote:
>> Which phenomenon prevents a black hole from ever forming. Yet
>> astronomers keep telling us they are all over the place.
> Astronomers have observed objects whose behaviour is entirely
> consistent with the existence of black holes as predicted by general
As far as I understand, all we can ever observe is black holes in the
making since the making can never (seem to) finish. IOW, the event
horizon never forms.
These almost-black-holes are virtually indistinguishable from black
holes proper. However, we don't have to speculate about the physics of
the insides of the black hole.
> The singularity being talked about there is an artifact of a
> particular coordinate system; the theory predicts that there is no
> *physical* singularity at the event horizon.
That theory can't be tested even in principle, can it? Therefore, it is
> It's true that we outside can't be absolutely sure that things are as
> predicted at the horizon itself, because any observer we sent in to
> check would be unable to report back. But in principle we can observe
> arbitrarily close to it. The observations we've made so far all fit
> the theory, and the theory doesn't present any obstacles to
> extrapolating those results to the horizon and beyond, so we accept
> the theory as valid.
Religious theories about the afterlife face similar difficulties -- and
present similar extrapolations.
> There *is* a difficulty at the very center of the hole, where there is
> a true singularity in the theory, so something else must happen there.
> But for other reasons we don't expect those effects to become
> important until you get very close to the singularity -- something on
> the order of the Planck length.
That's my point: such speculation must remaing mere speculation. The
universe doesn't owe us an answer to a question that we can never face.