Can math.atan2 return INF?

Marko Rauhamaa marko at pacujo.net
Tue Jun 28 02:23:26 EDT 2016


Gregory Ewing <greg.ewing at canterbury.ac.nz>:

> 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.

In Zeno's case, the limit is finite. Zeno's error is not realizing that
you can pack an infinite number of jiffies in finite time. In the black
hole case, the limit is infinite.

> 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.

An external observer never experiences any effect whatsoever (direct or
indirect) from an event horizon or a black hole.

> 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.

Not where I'm standing.


Marko


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