Seeing the entire future of the Universe

[Naty1]

What does " Sees the entire future of the Universe" mean? I can't even imagine seeing one minute into the future let alone the 'entire future'...

The interior structure of rotating black holes 1. Concise derivation
http://arxiv.org/pdf/1010.1269v3.pdf

[From the third paragraph, INTRODUCTION]

The Kerr geometry, and more generally the Kerr-Newman geometry, has two inner horizons that are gateways to regions of unpredictability, signalled by the presence of timelike singularities. In 1968, Penrose [5] pointed out that an observer passing through the outgoing inner horizon (the Cauchy horizon) of a spherical charged black hole would see the outside Universe infinitely blueshifted, and he suggested that the infinite blueshift would destabilize the inner horizon. The infinite blueshift is plain from the Penrose diagram, Figure 1, which shows that a person passing through the outgoing inner horizon sees the entire future of the outside Universe go by in a finite time.

 

[pervect]

Well, if you were to hover sufficiently close to the event horizon of a black hole, you could imagine, for instance, looking out and seeing the universe age at 1000x the rate at which it would age if you were out of the BH's gravity well.

So now all you need to do is imagine that factor of 1000 going up without bound - higher and higher - until you approach infinity, to understand what the paper is talking about.

Of course if that did happen, you wouldn't be alive to see it, because there'd be no way to survive an infinite blueshift, there is some maximum "survivable" blueshift based on your radiation tolerance.

The other issue is that even if you could survive that, the Kerr metric assumes that the amount of matter infalling isn't large enough to disturb the metric. If you've got a potentially infinite amount of energy infalling, obviously the idea needs to be re-examined.

Current thinking is that the Kerr metric isn't stable, and that the actual metric of a rotating black hole is "something else". The paper describes what that something else may be, the section you are reading is justifying why the authors feel the Kerr metric isn't really adaquate.

 

[Naty1]

The other issue is that even if you could survive that, the Kerr metric assumes that the amount of matter infalling isn't large enough to disturb the metric. If you've got a potentially infinite amount of energy infalling, obviously the idea needs to be re-examined.

Ah, that I did not know...thanks