OK, first let me tell you this is not my field..I was watching a program about the universe the other night. They also talked about the formation of black holes after stars had burned out. Now, my question is..."Is it possible that enough rubble could collect and form a super planet between the space of galaxies. If enough matter/rock/ice/rubble collected over time wouldnt it be possible that it could become massive enough to create a black hole, wonder just how big it would be? Would it be possible within our galaxy in some of the more barren areas of space..Now back to my biology...
Highly unlikely. Most of the ordinary (baryonic) matter in the universe is hydrogen (75%) or helium (25%). Therefore any large accumulation would turn into a star long before it could become a black hole.
I wondered about a similiar question a while ago; I wanted to know whether a neutron star could accumulate enough material to turn into a black hole. I unfortunately can't remember the details of the answer, except that it boiled down to "no". I think it may have involved x-ray and gamma-ray burst type phenomena, i.e. if you dump too much stuff onto the neutron star it will destabilise and eject some of it, but I might have just made that up. I doubt that an accumulation of the kind of matter you mentioned would even make it to the neutron star stage though, but I don't have much to back up that intuition.
I was thinking more along the lines of rock and other hard matter rather than gases. I am not sure if this hard matter would be star material even even it was the size of our sun. Example, if the earth was twice the size of our sun floating outside our solar systme halfway to the nearest star. Are you guys telling me that gravity would cause this mass to become some type of star? I thought that cold matter could become compressed without causing it to generate heat. Just an extra large ball of dirt...Massive with no internal fires..
Hydrogen, helium,nitrogen, carbon oxygen, neon,mangaan, silicium sulpher,iron,nicle it all fuses as the mass go up, I'm pretty sure that all elements somewhat fuse when you start reaching neutron star densities. So everything eventually fuses before it becomes a black hole
Probably there's a bound on the size of rocky objects---have you ever noticed how all of the rocky objects in our solar system are smaller than Earth (or so), and all of the bigger bodies are gaseous? Another thing to consider is that there's probably too low a density of ``loose matter'' between stars to get this behavior. Most matter in the universe is hydrogen gas, and dark matter. (We know dark matter doesn't interact with itself strongly, so it can't form black holes.)
Well actually once you reach iron fusion stops, because iron is the most stable element and thus has the lowest nuclear binding energy. Once you go above iron fission becomes favourable (in the sense that you will get energy from fission, while you have to put energy in if you want to continue with fusion). This is why the heavy elements are only produced in supernovae. (Stars die when they run out of fuel, i.e. when they have nothing but iron left in them (loosely speaking)). You're right, it wouldn't ignite into any "living" star, but an object made of Earth-like matter which was twice the size of the sun wouldn't be able to support its own weight, so something funny would surely happen. Nah can't do that, even the Earth is really hot in the middle due to being compressed. It will cool down eventually, but no matter what you do compressing things will always generate heat. I'm not really sure what would happen, but I'd guess that such an object would collapse itself into something like a brown or white dwarf star, which aren't really stars because there is no fusion occuring, they are usually just the remnant cores of dead stars. Originally though I thought you were asking how far you could push this, as in what would happen if you just kept piling matter on. This is where my neutron star "theory" came from, which again is not really a star, it is a compact object much closer in nature to a black hole than a normal star, prevented from final collapse to a black hole by something crazy like quark degeneracy pressure (i.e. the uncertainty principle), although I'm not sure anyone really knows. I'm not sure you can push past this phase to a black hole just by piling on more matter though, and maybe you can't even make it this far. Of course as Ben says this scenario would almost certainly never occur naturally. Maybe in a few thousand years we'll be able to attempt crazy experiments like this though.
A black hole forms basicly because of gravitational collapse,ones you get to neutron mater, you are left with a neutron soup and the object will resemble 1 single atomic nucleus. Hence you could say everything is fused to a single "atom" there won't be any iron atoms left that can be descrived as such.
I think you could deliberately make a black hole if you had sufficient technology and energy to do it. You would have to use a magnetic bottle to create a small black hole with say a moon and you would have to keep sufficient forces on it to keep it a black hole as you add ever more matter to it till it had sufficient mass to be a stable black hole (a few solar masses). If your bottle slips before that period, you have a hypernova force explosion. Then again, if you had that kind of technology, easier to just push large double stars into each other so they are above the mass limit to form a black hole. The original idea for a black hole a century or two ago was a super-massive star with an escape velocity faster than light. They knew nothing about collapsed stars then.
