Hi, I have a question, maybe someone knows details about that:

"What is the minimal Size/Mass of a black hole"

Meaning, how many Particles, such as Atoms do you need
to form a black hole.

Can a single Atom form a black hole?
Are at least 2 Atoms needed?

Or what combination of particles would form the smallest
black hole possible?

Do black holes exist at all?

For black holes in space, the mass must be 4 times the sun I thought? But nobody is entirely sure. Recently they discovered a star turned into a supernovae that was way too light for that. Could've been a binary system rotating into eachother.

Micro black holes, which means small, unstable black holes like they will propably be created in the LHC have a minimum mass of 10^16 TeV (10^-8 kg). The mass of a proton is 1,67*10^-27 kg, so you need about 6*10^18 protons/nucleons. So you need way more that a single atom.

http://de.wikipedia.org/wiki/Micro_Black_Hole
http://de.wikipedia.org/wiki/Proton

i wonder what happens then if you only have (10^16) - 1 TeV

It can not contract then?

I really wonder if black holes can really exist.
As gravitaion for example is not understood yet.
Especially what it does in very small distances.

I guess so. It has something to do with the Planck length.
However I read the Wikipedia article a bit more carfully now, and I found out that, if the assumption that there are small extra dimensions is true, then the minimum mass is only 1 TeV. Otherwise the LHC couldn't create black holes with its 14TeV.
This means you only need about 600 protons/nucleons. That's still more than an atom, but much less than my last number.

EDIT: (as you edited your post, too): I think Stephen Hawking proved that black holes do exist. But of course the current model isn't quite accurate, because in the center of a black hole the timespace warp is infinite and all phyisical laws are only valid under the assumption that it's amlost not warped at all.

But since its not possible to proove black holes by experiement or observation yet. It could be, that stellar black holes, are actually just
some super compact "normal" objects like neutron stars.
Wich would behave the same. (sucking in matter and such)

But "super compact "normal" objects" are much matter in small space, and if it's enough matter, then it would even suck in light with so much "power" that if it's near enough, it can't escape (event horizon). And that's pretty much the definition of a black hole.

The "smallest possible mass" of a black hole depends on your personal definition of what a black-hole IS...

In MY opinion, a super-massive-object is not yet a black-hole UNTIL its gravity
reaches the point where light can no longer escape. Then it IS a black-hole.

So with a bit of net-research, surely there is some information somewhere that
can give a genuine value to the strength of gravity required to stop light.
And from that value it should be possible to calculate how much mass is required
to generate that much gravity.

To the best of my knowledge, a neutron star is a super-heavy-object.
So dense it can nearly be called a single super-massive-ATOM!!
But it will never evolve into a black-hole I believe.
Both neutron stars AND black holes are generated at the heart of a super-nova.
Supernova's can create neutron stars when they are big enough 'crush' their own cores into a solid mass.
But sometimes, if they are big enough, they will create a black-hole instead.
I dont know if the reason for one or the other is due to the amount of mass,
that gets compacted, or if it is the power of the explosion that makes the difference.
I suspect its a combination of both...

So, to my mind, black-holes and neutron stars are related, but only as separate
branches on a star's evolution, not one leading to the other.

So I dont think "small black holes" are possible, the definition makes no sense.
But the LHA does create small amounts of anti-matter (which has nothing to do with back-holes BTW),
and super-dense-particles (call these super-dense-particles "micro black-holes" if you like).
The anti-matter rapidly "delf-destruct"s, and is such small amounts it is harmless.
And (I believe) the super-dense-particles "evaporate" as they are pulled apart by
the gravitational/elelctrical charges of the nearby (and far more numerous) atoms of normal(unmodified) matter.

How about when we find out, that gravitation
can not bend space enough to stop a lightwave from
escaping.
Then black holes would not be possible.

And as gravitation is not even explained yet, I wonder
why everyone preassumes that black holes are a fact.

Thats also why the question about super small black holes.

In these dimensions, quantum mechanics rule,
making the current rules of relativity theory not appliccable.

So how can black holes be derived from relativity theory?

Eh? Gravitation HAS been explained.
Gravitation is not a force as such, it is the "shape" of space-time...
Mass bends space, not gravity, gravity is the 'shape' of the bend that mass has created.
You know, ye-old rubber-sheet example and all that...

And black-holes have(apparently) been observed, kindof.
As matter falling in is torn asunder, just BEFORE the event horizon,
it generates huge amounts of x-ray radiation.
Some of this radiation manages to stay in orbit outside the event-horizon
long enough to get thrown off the north and south 'poles' of a spinning black-hole.
These x-ray "fountains" have been obverved many times...
Not really 'proof', but its the best we can get without visiting one, or making our own...