Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Martin Brown <'''newspam'''@nonad.co.uk>
Newsgroups: sci.electronics.design
Subject: Re: OT: More about the universe and black holes
Date: Thu, 5 Dec 2024 09:34:15 +0000
Organization: A noiseless patient Spider
Lines: 46
Message-ID: <virs34$1gv4g$1@dont-email.me>
References: <vipcj1$puc1$1@solani.org> <vipfn9$rmtm$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Thu, 05 Dec 2024 10:34:28 +0100 (CET)
Injection-Info: dont-email.me; posting-host="6ad25a792198da0235e030bbf8166c13";
	logging-data="1604752"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18WphWyyd253hSoWULj7/9TBA6l2EtXzUj5fN/G7uVE0Q=="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:0/vNjG7hUvLInsrDrZ0475BwJLc=
Content-Language: en-GB
In-Reply-To: <vipfn9$rmtm$1@dont-email.me>
Bytes: 3020

On 04/12/2024 11:54, Jeroen Belleman wrote:
> On 12/4/24 11:57, Jan Panteltje wrote:
>> Could dark matter have been forged in a 'Dark Big Bang?'
>>   https://www.space.com/second-big-bang-second-dark-matter
>>
>> Are planet-killing black holes hiding inside your cat?
>>   https://www.space.com/primordial-black-holes-cat-big-bang
> 
> Hollow out the earth? Preposterous! No cavity can persist
> in the core of an object big enough to be drawn into the
> shape of a sphere under its own gravity.
> 
> Tiny black holes that would drill microscopic tunnels
> through matter wouldn't go unnoticed. I think they don't
> exist. For that matter, I think black holes, in the sense
> of gravitational singularities, don't exist either, for
> the simple reason that their mass energy, even though huge,
> is not infinite.

Indeed. It is possible that small sized black holes do account for some 
of the missing matter but you can't hide them so easily. If they were 
too low a mass they will already have evaporated by now from Hawking 
radiation. If there were a range of masse sthere should be some around 
evaporating right now and they would have a particular signature that GR 
can predict.

It is just possible that the next generation supercolliders might be 
powerful enough to momentarily create nano BH objects once in a 
bluemoon. Hyper energetic cosmic rays might do this too but their decay 
products are impossible to observe.
> 
> If a theory predicts a singularity, this merely tells us
> the theory is incomplete.

The theory could be complete if it only posits singularities in places 
where you can never observe them and report your findings. With the 
possible sole exception of a maximal angular momentum Kerr metric I 
think that Penrose's cosmic censorship conjecture holds.

https://en.wikipedia.org/wiki/Cosmic_censorship_hypothesis

I don't know how strongly supported it is these days.

-- 
Martin Brown