Assignment Versus Equality

[Ian Kelly]

On Tue, Jun 28, 2016 at 10:39 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>
> (sorry for the premature previous post)
>
> Random832 <random832 at fastmail.com>:
>> All objects, not just black holes, have those properties. The point
>> here is that we are in fact observing those properties of an object
>> that is not yet (and never will be) a black hole in our frame of
>> reference.
>
> A physicist once clarified to me that an almost-black-hole is
> practically identical with a black hole because all information about
> anything falling in is very quickly red-shifted to oblivion.
>
> However, there is some information that (to my knowledge) is not
> affected by the red shift. Here's a thought experiment:
>
>        ----------
>       /          \
>      /  (almost)  \               N
>     |    black     |              |
>     |     hole     |              S
>      \            /
>       \          /
>        ----------
>
> We have a stationary, uncharged (almost) black hole in our vicinity and
> decide to send in a probe. We first align the probe so it is perfectly
> still wrt the black hole and let it fall in. Inside the probe, we have a
> powerful electrical magnet that our compass can detect from a safe
> distance away. The probe is also sending us a steady ping over the
> radio.
>
> As the probe approaches the event horizon, the ping frequency falls
> drastically and the signal frequency is red-shifted below our ability to
> receive. However, our compass still points to the magnet and notices
> that it "floats" on top of the event horizon:
>
>        ----------
>       /          \
>      /  (almost)  \ N
>     |    black     ||
>     |     hole     |S
>      \            /
>       \          /
>        ----------
>
>
>            /
>           / compass needle
>          /
>
> The compass needle shows that the probe is "frozen" and won't budge no
> matter how long we wait.

I'm skeptical of this. As the ping frequency falls drastically due to
relativistic effects, so too does the observed current powering the
electromagnet, does it not?