[ExI] ligo again: was: RE: puzzling

[John Clark]

On Mon, Oct 19, 2020 at 1:44 PM spike jones via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

 >
>
>
> *I simultaneously pondered that black hole merger announced in early
> September.  That one too has me leaning toward the simplest solution: that
> these two black holes formed in the plane of an enormous accretion disc and
> grew to their absurd size by absorbing material from that disc,*


It's difficult for a small Black Hole to grow into a large one in the
limited time available by that method because as matter starts to spiral
into the hole it gets very hot and produces a lot of x-rays that push much
of the remaining gas away. Maybe in the very early universe it is formed by
direct collapse from a cloud of gas to a Black Hole without ever becoming a
star or even getting very hot because in some ways it's easier to make a
large Black Hole than a small one because, although you need more matter,
you don't have to concentrate it as densely to make a large black hole as
you do to make a small one. For example if you wanted to make a one solar
mass Black Hole you'd have to concentrate matter so it had a density
1.8*10^16 times greater than water and have a radius of 3 km, but if you
wanted to make a 11 billion solar mass Black Hole you'd only need to
concentrate matter so it had the density of air at sea level, it would then
have a radius 2 1/2 times that of Pluto's orbit and form a Supermassive
Black Hole.

But I have a hunch we're not gonna really understand how they formed until
we know what dark matter is, after all there's five times as much of it as
there is normal matter so it must play a part in the formation of a black
hole.

 John K Clark
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