# B Total % of Photons Redshifted While Moving Away From a Black Hole?

#### metastable

So? You are describing something that's not observable (because it's not part of the observable universe), but is observable (because of its effects). So it's observable and not observable. I don't think you actually have a consistent scenario here.
Not observable via light (and also because it's a black hole)... but still observable via its gravity.

We can't "see" black hole mergers but we can measure the gravity waves.

#### Ibix

Not observable via light (and also because it's a black hole)... but still observable via its gravity.
It's not clear to me that this is a consistent model. If the black hole is eternal, then yes you can detect its gravity at any distance (in principle). However, such a universe does not have the concept of "observable universe". The observable universe is a concept in FLRW spacetimes, in which black holes may form but are simply a kind of extreme over-dense patch. They don't have a long-range gravitational effect different from any other kind of over-dense region.
We can't "see" black hole mergers but we can measure the gravity waves.
Gravitational waves (nitpick: gravity waves are a kind of surface wave on liquids) propagate at the speed of light. If we can observe them, we can observe light emitted at the same time.

#### metastable

However, such a universe does not have the concept of "observable universe". The observable universe is a concept in FLRW spacetimes, in which black holes may form but are simply a kind of extreme over-dense patch.
So the distances I refer to in my original post (black hole radius = observable universe radius and rough craft distance = 2 black hole radii from geometric center of black hole) should be taken to mean the distances are derived from estimates of the size of the observable universe in the actual observable universe.

#### PeterDonis

Mentor
The black hole in the scenario is sized in such a way that the effects it causes in the scenario are still detectable while the black hole itself is completely outside the observable universe.
This model of yours is personal speculation, as you have already been told in at least one previous thread. Please do not post about it further or you will receive a warning.

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