

Wormholes Untangle a Black Hole Paradox - digital55
https://www.quantamagazine.org/20150424-wormholes-entanglement-firewalls-er-epr/

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dave_sullivan
Can someone explain why black holes are often assumed to "lead somewhere"?
Aren't they just Very Dense Objects in space--hence, they lead to the surface
of the object?

Also, the event horizon can be quite wide, but why the assumption that there's
some kind of "singularity" inside? There's a center of mass, but what's to say
the central massive object is not quite large in volume and organized at
scales/levels near the bottom of the planck scale? Or is that what they mean
by singularity (not so much a single point in space as a small but quite
massive object residing within the event horizon)?

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PuffinBlue
There are a lot of questions in there but I can try and answer a few:

1) Leading somewhere...

It's not really assumed they do but some speculate that they could.

2) Surface of the object/singularity/wide event horizon.

This is tricky to explain quickly and simply but here goes. In a very simple
sense, a 'singularity' is really a name given to a thing which can't be
explained by known laws or perhaps involves an infinity that shouldn't be able
to exist in reality or some such. It's a name for a thing that by it's
existance causes a 'problem' in that we an't fully explain it.

That's the layman's definition I often hear but in reality to be a singularity
it needs to fit a set of criteria regarding geodesics and curvature etc that
wikipedia can explain.

In the case of black holes it's used to refer to the infinitely dense mass
that 'is' the black hole, or rather the point at which you'd reach if
theoretically you fell all the way down to it. This isn't a small but massive
object - it's an infinitely dense object.

So...there's the matter of infinitely dense. Once something loses the ability
of its outward pressure of its mass etc to resist the inward crush of gravity,
you get an object that becomes denser and denser and denser ad infinitum
because it continuously collapses under its own gravity. It simply continues
to collapse inwards on itself forever becoming 'infinitely dense' as it gets
smaller and smaller.

There is no known reason why it wouldn't continue to collapse inwards on
itself to an infinitely small point. There is no known reason why it would
stop at the planck scale, no mechanism to suddenly overcome the immense
gravity, and that's the problem really.

There is an assumption of a singularity because in order to create a 'strong'
enough curvature of space-time such that light couldn't escape (i.e. to form
an event horizon), you need to have a sufficiently dense object. The only way
to achieve this is with an object that has collapsed past the 'point of no
return' and continues to collapse in on itself (i.e you need a singularity).

Other fantastically dense objects like neutron stars lack the density, you've
got to go 'super dense' and then you just get the run away effect and a
singularity.

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btouellette
Doesn't any spherically symmetric configuration of mass compressed into an
area smaller than the Schwarzschild radius create a gravitational force strong
enough such that light can't escape? If there was an unknown force that could
prevent the collapse at some level below the Schwarzschild radius it would
still be dense enough to capture light. And there certainly could be since our
understanding of things at the Planck scale isn't complete.

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PuffinBlue
First question answer: yes

Second question: yes maybe. No one knows.

An interesting aside is that infinite density occurs only (I think) with no
rotating singularities which don't exist in reality. Anything rotating will
produce a non-infinitely dense singulatiry somehow, though the details of the
maths behind that elude me.

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techdragon
Kerr vs non Kerr blackholes is where I usually start replying with "we don't
know" to every second question.

But broadly speaking the inside is theorised to be a 1 dimensional torus
having only diameter as a measurable quantity other than the location of its
center of mass. This is opposed to a zero dimensional point having only the
location of its center of mass. This means the mass is distributed through the
torus and is "less infinite" in the aleph zero vs aleph one kind of way.

It just gets weirder from there haha

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Errorcod3
Interesting using gloves for an analogy.

I've gotten so use to using 1's and 0's.

