[scherado (OP)]

There seems to be no controversy (in Science) with respect to the existence of the Black Hole. My question:

Is there more than one Black Hole in the Universe?

[PmbPhy]

There seems to be no controversy (in Science) with respect to the existence of the Black Hole. My question:

Is there more than one Black Hole in the Universe?

Sure. In fact in this galaxy alone there could be a million of them.

[evan_au]

It is thought that there is a supermassive black hole in the center of (nearly) every galaxy.
See https://en.wikipedia.org/wiki/Supermassive_black_hole

Supernova of a large star is very likely to produce a black hole. It is thought that there are about 30 supernovas per 1000 years in our galaxy, but ancient astronomers have only reported about 3 every 1000 years.
- One possible reason for the discrepancy is that the black hole swallows the star before it can emit the massive burst of superheated gas that glows for months.
- A more boring reason may be that the ancient Greek philosophy that "the stars are unchanging" may have inhibited Europeans from reporting such events for many centuries. But Chinese astronomers were not under this illusion.
See: https://en.wikipedia.org/wiki/Supernova#Core_collapse

[PmbPhy]

It is thought that there is a supermassive black hole in the center of (nearly) every galaxy.

Another black hole is my wallet. It seems that every time I put something in it, it disappears in microseconds! 

[Bill S]

Another black hole is my wallet. It seems that every time I put something in it, it disappears in microseconds!

Just wait until you're old!  Then it's your wallet that disappears, along with your car keys, specs, mug of tea (or coffee, of course) and loads of other things.  Most of them seem to turn up again in this Universe, but I suspect some may not.

[scherado (OP)]

As for the question in the title, the merger of two black holes was witnessed (recorded by LIGO) just 3 years ago.

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I did read about the event you referenced and thank you for using the word "merger." It is precisely what I needed to advance an argument I've been honing over time.
 
I'll post an explanation as a new post in this thread as soon as it is written. Thanks.

[Halc]

I did read about the event you referenced and thank you for using the word "merger." It is precisely what I needed to advance an argument I've been honing over time.

Merge seems appropriate for two things of similar order of magnitude of mass.  But if one is tiny and the other huge, it seems more like the little one falling into and adding to the bigger one, but the process is really the same.

Does a meteor fall to Earth or do the two just merge?  Or maybe the Earth falls down onto the rock and becomes this huge meteorite on it.

[evan_au]

...an argument I've been honing over time... I'll post an explanation as a new post in this thread as soon as it is written.

Merger of black holes (or merger of two neutron stars to form a black hole) is mainstream science, based on scientific observation of the real world.
See: https://en.wikipedia.org/wiki/List_of_gravitational_wave_observations

Questions about black holes belong in the "Physics, Astronomy & Cosmology" section of the forum.
However, a proposed explanation of the structure of the cosmos based on black holes belongs in the "New Theories" section of the forum.
@scherado, I recommend that you post your explanation there instead. 

[scherado (OP)]

Merge seems appropriate for two things of similar order of magnitude of mass.  But if one is tiny and the other huge, it seems more like the little one falling into and adding to the bigger one, but the process is really the same.

Does a meteor fall to Earth or do the two just merge?  Or maybe the Earth falls down onto the rock and becomes this huge meteorite on it.

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Thanks!! Your new answer can be used to advance my argument a very long way, which I've been working on sporadically over the last few years.

FYI, I do informal debating on scientific subjects, as well as others, and have taken on the task of forming an unassailable response to those who accuse others of being so intractable in disagreement with an argument as to be guilty of violating the "obvious" truth of "2 + 2", which sometimes appears as, "2 + 2 = 5." I'm sure more than a few here have seen such things. This site not being a debate forum, such accusations may not actually occur on this site.

If I were to apply your question about Earth and a meteor in my argument, then I begin with:

1. Can we express the event in the form "1 + 1 = ___?" This, you will see, is an acceptable substitute of "2 + 2" in the abstract or in the classroom, if you like?

2. Apply the new addends (replace the 1s): "Meteor 'falls to' Earth = ____"; the operation (process) "+" become "falls to" and the addends (1 and 1) become "meteor" and "Earth" respectively. You see immediately that I've replaced what began as two identical things in the abstract--the two 1s--by two non-identical things.

At this point, the astute reader will wonder, are there to be found in Nature or by human construct any two things that are identical? The question is not without significance, though one might think it to be obvious as "no." Yet, in grade-school, high school and well beyond, we treat 1 + 1 = 2 as an unassailable truth, and it is just that always when and only when the addends remain abstract.

There is more, but I have to go now.
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Based on the reply by "evan_au", I won't be taking up any more of your time, as you all are, I suspect, still looking for adequate clothing.
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Questions about black holes belong in the "Physics, Astronomy & Cosmology" section of the forum.
However, a proposed explanation of the structure of the cosmos based on black holes belongs in the "New Theories" section of the forum.
@scherado, I recommend that you post your explanation there instead.

[evan_au]

In an interview, Astrophysicist Priya Nataranjan quoted the current estimate on the mass of black holes in a galaxy:
- The central massive black hole has a mass around 0.1% of the mass of the central bulge of the galaxy
- The central black hole + stellar-mass black holes in the galaxy make up around 0.1% of the total mass of the galaxy

The interview is available here (quite a good series):
https://player.fm/series/the-after-on-podcast/ep-36-priya-nataranjan-mapping-the-heavens

[Bill S]

Interesting stats, Evan. Multiply this by the number (and size) of galaxies and you have the number for the Universe.

Wait! We can't see all of the Universe; we don't know what is out there.  The answer to the OP must be something akin to the answer to "how many angels can dance on the point of a needle".

[geordief]

Interesting stats, Evan. Multiply this by the number (and size) of galaxies and you have the number for the Universe.

Wait! We can't see all of the Universe; we don't know what is out there.  The answer to the OP must be something akin to the answer to "how many angels can dance on the point of a needle".

Are there any educated guesses at all as to the ratio between the observed and the unobserved universe? Could it be an infinite ratio?

[Bill S]

Could it be an infinite ratio?

Would that be the common ratio of an infinite series, which is the sum of an infinite sequence? 
If so, I'm outta here. Peace out y'all!

[scherado (OP)]

Is there more than one Black Hole in the Universe?

The answer to the OP must be something akin to the answer to "how many angels can dance on the point of a needle".

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The only reason I asked whether there were more than one is that I could not use the entity "Black Hole" as an addend in the argument I'm honing if there were not more than one. Now, you can be sure that I did assume that there were more than one. It is what happens when they become the addends in an equation that is relevant to my argument.

Sneak preview: Describe the operation, denoted by "+", in the equation, "1 + 1 = ____", when the addends are Black Holes.

Now you know were I'm going with this.

[scherado (OP)]

"One and one don't make two. One and one make one."
-- The Who

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Thanks. You've revealed that you know that addition inside the classroom, in the abstract, is nice and easy, but less so outside. So, tell me, have you ever accused someone of being so obstinate in accepting your argument that it is tantamount to a denial of the result of "2 + 2?"

[evan_au]

Are there any educated guesses at all as to the ratio between the observed and the unobserved universe? Could it be an infinite ratio?

That question comes up later in the same interview with Prya Nataranjan.
As I recall, "an infinite universe is still on the menu of possibilities".

[geordief]

Are there any educated guesses at all as to the ratio between the observed and the unobserved universe? Could it be an infinite ratio?

That question comes up later in the same interview with Prya Nataranjan.
As I recall, "an infinite universe is still on the menu".

thanks. I will give it a listen if I get time.