On 8/19/17 2:00 AM,
pora...@gmail.com wrote:
> On Friday, August 18, 2017 at 11:01:14 PM UTC+3, Edward Prochak wrote:
>> On Friday, August 18, 2017 at 3:54:19 PM UTC-4, Odd Bodkin wrote:
>>> John Sefton is incensed about the idea of a black hole, because he read
>>> somewhere that the central idea of a black hole is infinite gravity, and
>>> he will insist that gravity has to be finite (even though he believes
>>> the size of the universe is infinite). And because he believes this is
>>> the central lynchpin of black holes, then a belief in finite gravity
>>> means to him that black holes are denied.
>>>
>>> But John is kinda missing the boat on what makes a black hole.
>>>
>>> First of all, let's get straight what a black hole is. A black hole
>>> happens when a sufficiently large but FINITE amount of matter falls
>>> inside a sufficiently small but FINITE radius. This radius is called the
>>> Schwarzchild radius. That radius is r = 2GM/c^2. All you have to do is
>>> get more mass than M inside that radius r, and you will have a black
>>> hole. A black hole simply means that ANYTHING that falls inside this
>>> radius will never get out or send anything out. Things outside of this
>>> radius can be perfectly happy, orbiting around and never falling in. The
>>> idea of a black hole swallowing everything on the OUTSIDE of this radius
>>> is just bullshit, gradeschool bullshit. Some stuff will fall in, sure,
>>> just like some stuff falls into the sun, but the planets have not fallen
>>> into the sun for billions of years.
>>>
>>> So far, there is absolutely nothing about infinite anything here.
>>>
>>> So now the question is, why don't ALL stars compress under gravity and
>>> become black holes. The reason is that there are sources of outward
>>> pressure, obviously, and if the outward pressure equals the inward pull
>>> of gravity, then collapse doesn't proceed.
>>>
>>> In ordinary burning stars, what provides the outward pressure is heat
>>> from nuclear fusion. Heat pushes matter outward, as anyone who has
>>> watched a firecracker knows. If gravity is enough to pull it in (more
>>> than a firecracker's gravity, for sure), then there can be a balance,
>>> which is like our sun.
>>>
>>> When the fuel for fusion is gone, then there is no fusion to provide
>>> heat to push things outward, and the star starts to collapse, until a
>>> new outward force pushes it out. That outward force is almost exactly
>>> the same thing that makes a metal solid. It's called electron
>>> degeneracy, and it's basically the Pauli exclusion principle at work.
>>> Electrons in the same state cannot get too close to each other, because
>>> they are fermions. It's this repulsion, not from electrostatics, but
>>> from Fermi statistics and the Pauli principle, that makes metal solid,
>>> and it also makes burnt-out stars resist gravitational collapse.
>>>
>>> But if you get enough gravitational pressure coming from the further
>>> collapse, then you can introduce something that only happens extremely
>>> rarely in solid materials, and that's the electron being squeezed into
>>> the nucleus for long enough periods of time that it interacts with a
>>> proton and generates a neutron. Do this enough, and all of the atoms
>>> collapse into the size of their nuclei, which is a trillion times
>>> smaller and more dense. Since there are equal numbers of protons and
>>> electrons, you're going to end up with something like a solid again, but
>>> now made up entirely of neutrons. The good news is that neutrons are
>>> also fermions, and the Pauli exclusion principle also applies to them,
>>> and so you can't just squeeze neutrons together forever, before they
>>> want to push each other away and you now have outward pressure. When
>>> that balances gravity, then you have a stable neutron star, of which
>>> we've seen plenty.
>>>
>>> But if this neutron star collapse brings enough mass close enough
>>> together that you're inside the Schwarzchild radius, then gravity is
>>> strong enough to not be balanced by neutron degeneracy. So then another
>>> collapse happens just like the previous ones. The difference here is
>>> that we're not aware of any other layer of degeneracy pressure that
>>> might cause another balance with gravity. So AS FAR AS WE KNOW, there is
>>> nothing to stop the collapse from gravity and it is ASSUMED that it will
>>> just continue unstopped. However, as this all happens inside the
>>> Schwarzchild radius, we WILL NEVER KNOW anyway, because we can't see
>>> anything coming out to tell us what's going on.
>>>
>>> All of this is to point out that infinite gravity is NOT a logical
>>> must-have for black-holes. All that is needed is enough FINITE gravity
>>> to overcome the FINITE neutron degeneracy pressure, and you'll have a
>>> black hole, and what happens inside after that is moot.
>>>
>>> So John .... get over it. The crap comic book stuff you read about black
>>> holes is cheapo, sloppy, popularization nonsense.
>>>
>>>
>>> --
>>> Odd Bodkin -- maker of fine toys, tools, tables
>>
>> Very nice exposition there Odd. Good work.
>> ed
> ====================
> yes indeed good detailed explanation
> now
> I am not sure that odd indicate that
> some energy **does** go out the back hole
> ie
> EM WAVES ARE EMITTED FROM SOME center OF BLACKHOLE
Nope. There is no EM wave emitted from inside the event horizon. Zero. Nada.
>
> and me
> Y.Porat
> proved that
> EM WAVE HAS MASS !! THE ONLY MASS !!!
> -----
> TIA
> Y.Porat
> ==========================