Black Holes

[pgrmdave]

What percentage of stars could become black holes? And do black holes eventually die, or would they exist forever?

[bumab]

I'm not sure the percentage, but balck holes do eventually die- they evaporate through Hawking radiation, I believe. I'll go look it up.....

[UncleAl]

A star's evolution is determined by its mass. If the star is one of a binary system, it can evolve and capture mass from its partner, changing its ultimate destination (including Type I supernovae). Look it all up in Google. The world is raining knowledge. Don't use your soup bowl as a rain bonnet.

 

Small stars (the Sun) will eventually bloat, blow off their outer shell of mass, and leave behind a white dwarf that will slowly cool. It's boring overall and tough on the planets.

 

Heavier stars will go Type II supernova: When their cores reach iron by fusion there is no further energy to be had to keep the star inflated, temperature vs. gravitation. The extraordinary temperature of that iron core plus the increasing pressure lead to sudden photodisintegration of the iron nuclei - and that is endothermic! Suddenly, nothing is holding the star inflated. The core squeezes into neutronium with a huge blast of neutrinos (90% of the total energy emitted - the big flash to follow is piddles) as electrons and protons combine. What happens next depends on the amount of mass present.

 

1) The remaining core is around 1.5 solar masses. As the outer layers blow off into a Type II supernova, the core is stable as a very hot, very rapidly rotating neutron star.

 

2) If the core is much larger, even Pauli exclusion can't keep it inflated against gravitational pressure. The neutronium collapses all the way to a singularity surrounded by a black hole.

 

However... SN1987a which is relatively close by and very visible, star to Type II supernova to current remnant,

 

http://csep10.phys.utk.edu/guidry/violence/sn87a.html

http://zebu.uoregon.edu/~soper/StarDeath/sn1987a.html

http://chem.tufts.edu/science/astronomy/SN1987A.html

 

left no neutron star or black hole visible to date, even by inference. This is a curiosity with no explanation.

[maddog]

I remember from my Astrophysics class that mass limit of 3.1 solar masses for a star would have as part

of the eventual supernovae would proceed to a black hole (thereby bypassing the neutron star outcome).

You have tell-tale signs a sizeable quantity of X-Rays from the accretion disk. :xx:

 

maddog

 

ps: Text: Astrophysics, Martin Harwitt

[Odin]

Well Blackholes do not exist. If you look at Einsteins Special Theorom and the equation E=mc^ you will see it is nothing more than a hyped up creation from Newtons Theory of Potential Energy.

The theory of Einstein is merely that if an object had an infinite mass it would have an infinite energy field.The only thing is that the object would have to be travelling at the speed of light. Even if only in rotation by the collapsing upon oneself the mass would become so small it would no be able to aquire an infinite mass as mass is existance in substance. The smaller the collapsed star became from rotation the energy field would increase but only to a certain degree before its mass would become less than one and the collapsed star would not be able to sustain its momentum or energy levels and the collapsed gases would expand again but since the star is now inactive would just dissipate into the universe

[InfiniteNow]

Well Blackholes do not exist.

How then do you explain those intense gravitation wells which impact the space around them but emit no light?

[ronthepon]

Well Blackholes do not exist....

...

The theory of Einstein is merely that if an object had an infinite mass it would have an infinite energy field.The only thing is that the object would have to be travelling at the speed of light. Even if only in rotation by the collapsing upon oneself the mass would become so small it would no be able to aquire an infinite mass as mass is existance in substance. The smaller the collapsed star became from rotation the energy field would increase but only to a certain degree before its mass would become less than one and the collapsed star would not be able to sustain its momentum or energy levels and the collapsed gases would expand again but since the star is now inactive would just dissipate into the universe

Well, if you can argue against the infinite mass concept, go ahead, you're right.

 

However, black holes do not have infinite mass.

 

The rest of your post is a bit tough to understand for me, are you trying to convey that as the star or whatever body gets smaller, some how the mass gets less? Because that would not be true.

[God's servant]

Well Blackholes do not exist.....

 

And you can prove this how??? All you have there are theories. To have a truth you have to have proof. You have no proof, just theories.

[Little Bang]

You right ron, not infinite mass but infinite density.

[WillieB]

Ron and Little Bang:

 

In your heart of hearts, do you really believe in an infinitely large gathering of mass contained within an infinitely small point. If so you are a captive of esoteric mathematics extended to an infinitely ridiculous extent.

[ronthepon]

Ron and Little Bang:

 

In your heart of hearts, do you really believe in an infinitely large gathering of mass contained within an infinitely small point. If so you are a captive of esoteric mathematics extended to an infinitely ridiculous extent.

Maybe not, but there have been a lot of things that I haven't believed in the 'heart of my hearts', and have come out to be true. While the concept is not exactly extremely practical, it is possible.

 

Because for a density tending to infinity, what you need is not infinite mass, but infitessimally small dimension. If you have a even a microgram in a cube with a side of one nanometer, you'll have an enormous density.

[Janus]

You right ron, not infinite mass but infinite density.

 

Actually, neither is required for a black hole. If you take the volume of a black hole as defined by the radius of it event horizon, you can find the density of the black hole by

 

[math]1.8 \frac{g}{cm^3} x 10^16 \left ( \frac{M_s}{M} \right )^2[/math]

 

Where Ms is the mass of the Sun and M the mass of the black hole.

 

The inifinite density arises only if you consider the singularity. And while present models predict a singularity at the center of a black hole, we do not know for a fact that one exists there, and the lack of a singularity does not preclude the existence of a black hole. All you need for a black hole is a body which has a density equal to or greater than the denstiy given in the formula.

 

Also note that as the mass of the blackhole increases, the density decreases, a super massive black hole of 100,000,000 solar masses would only have a density of 1.8 g/cm^3

[WillieB]

Maybe not, but there have been a lot of things that I haven't believed in the 'heart of my hearts', and have come out to be true. While the concept is not exactly extremely practical, it is possible.

 

Because for a density tending to infinity, what you need is not infinite mass, but infitessimally small dimension. If you have a even a microgram in a cube with a side of one nanometer, you'll have an enormous density.

 

Yes. But you still wouldn't have either infinite mass or infinite density. A singularity is only a theoretical construct. Mass has substance. I firmly believe that substance cannot be compressed to an infinitely small point. What is an infinitely small point anyway? It is nothing.

[CraigD]

A singularity is only a theoretical construct. Mass has substance. I firmly believe that substance cannot be compressed to an infinitely small point.

Quantum physics predicts something like what WillieB believes, in that it’s not really meaningful in its formalism to speak of any particle having any size – which is why, when we say something like “The classical electron radius is about 2.818 \times 10^{-15} \, \cbox{meters}[math]”, we’re careful to qualify this as classical, meaning “sort of equivalent in terms of classical physics”. Particles, and ensembles of particles, exist only in terms of their measurable interaction with other particles, so while they have position and mass, they don’t precisely have volume.

 

Some of the mass in ordinary matter consists of fermions, such as quarks (surprisingly, only about 1%, the rest being made of bosons, such as gluons). Although the laws of quantum physics don’t prohibit all of the bosons in the universe having the same location, they do prohibit fermions from doing this (per a part of the Fermi-Dirac statistic called the Pauli exclusion principle), so no matter how much ordinary matter is compressed, quantum physics predicts that there’s a density that it can’t exceed. Matter that is as dense as possible is called fully degenerate.

 

When predicting the behavior of objects like black holes, quantum physics comes up vague on precisely what this maximum density is. This is because, although quantum mechanics predicts (a possible incomplete list of) various kinds of degenerate matter for various maximum densities, it doesn’t predict how many kinds there are.

 

This is what quantum physics predicts a black hole is like. Classical physics predicts that a black hole contains an infinitely dense point of finite mass, its “singularity”.

 

I’ve a hunch quantum physics is more right in its prediction than classical physics is in its, but just a hunch. The experiments necessary to know more appear, at present, to be beyond human capability. When experimental physics has the ability to either create or visit black holes, , or some really clever way of answering these questions in a round-about way is found , we’ll be able to say more.

[Europa]

And you can prove this how??? All you have there are theories. To have a truth you have to have proof. You have no proof, just theories.

 

A theory it may be, but a most feasible theory at that.

 

Let me explain as a 2 year SETI Institue scientist. If you apply the faster the rotation, the lower the density around the equator, you quickly and logically acquire the fact that a black hole(if it could exist) would not at all be a disk. The object would be pulled from its center in which a large mass(spherical) would appear.

The faster the rotation, the lower the density around the equator is not theory, but an observable mathematical fact:) . Take the earth for example.

Due to its rate of rotation, it has developed bubbles if you will at its north and south poles, and just a little at it's equator;)