Black holes, infinite density and the Eternal God

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This whole thread question is irrelevant if we clarify one thing: Black Holes are not infinitely dense. I’m not sure where this idea came from but it is certainly not true; their density is incredibly great, but not infinite.

If the density of a black whole WERE infinite, it would be able to compact all of the matter in the universe into space smaller than an atom; smaller than a sub-atomic particle. The fact that black holes do not do so proves they are not infinitely dense.
 
dshix said:
This whole thread question is irrelevant if we clarify one thing: Black Holes are not infinitely dense. I’m not sure where this idea came from but it is certainly not true; their density is incredibly great, but not infinite.

If the density of a black whole WERE infinite, it would be able to compact all of the matter in the universe into space smaller than an atom; smaller than a sub-atomic particle. The fact that black holes do not do so proves they are not infinitely dense.
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You are mistaking infinite density for infinite mass. A singularity means that the mass (the collapsing core of the supermassive star) has collapsed down into a point. A point has no dimensions, which means that it has no volume, or expressed mathematically, v=0. Density is mass (say, kilograms) divided by volume (cubic centimeters), or m/v, expressed in kg/cm^3. However, in a singularity m/v becomes m/0. Anytime you have a number divided by zero, the only result is infinity. Therefore, the density of the singularity at the center of the black hole is infinite.

However, the mass is not infinite, and therefore the black hole is not capable of sucking all the matter in the universe into it. A supermassive star has a finite (albeit huge) mass. Imagine a supermassive star with a stable planetary system around it. If all the star’s mass collapses into a singularity and forms a black hole*, the density of the singularity is infinite, but the mass is the same it was before. The planetary system was stable before, and it is still stable; the planets will continue to revolve around the black hole.

*This isn’t really the way that it happens; a lot of the stars mass is blown away. I put it this way just for illustration.
 
DaveBj said:
You are mistaking infinite density for infinite mass. A singularity means that the mass (the collapsing core of the supermassive star) has collapsed down into a point. A point has no dimensions, which means that it has no volume, or expressed mathematically, v=0. Density is mass (say, kilograms) divided by volume (cubic centimeters), or m/v, expressed in kg/cm^3. However, in a singularity m/v becomes m/0. Anytime you have a number divided by zero, the only result is infinity. Therefore, the density of the singularity at the center of the black hole is infinite.

However, the mass is not infinite, and therefore the black hole is not capable of sucking all the matter in the universe into it. A supermassive star has a finite (albeit huge) mass. Imagine a supermassive star with a stable planetary system around it. If all the star’s mass collapses into a singularity and forms a black hole*, the density of the singularity is infinite, but the mass is the same it was before. The planetary system was stable before, and it is still stable; the planets will continue to revolve around the black hole.

*This isn’t really the way that it happens; a lot of the stars mass is blown away. I put it this way just for illustration.
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That was helpful, I had the same confusion… 😊
 
DaveBj said:
*This isn’t really the way that it happens; a lot of the stars mass is blown away. I put it this way just for illustration.
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GRRRR!!! . . . a lot of the star’s mass . . .

Proofread. Even at 0600.
 
Layp3rs0n said:
So a black hole is defined as a super massive star that has collapsed on itself to a point in which its density is infinite. This point of infinite density is called a singularity. But isn’t God the only thing that has no limits? How can something be infinity small or dense? It seems to suggest a black holes density is without limits. Presumably, time also shrinks to nothing in a singularity. So it has no time. It is like it exists in eternity. I am confused…really confused. God exists outside of time and is infinite. On that note does He exist in a state of singularity?
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Well first of all one might ask:
  • are black holes real? - sure there is evidence for what something might be a black hole (BH) if interpreted according to the Schwarzschild solution of General Relativy… HOWEVER there are other explainations outthere that fit the data and do not invoke the concept of black hole… but for now let’s assume BHs are real
  • Is the singularity really of infinite mass? - We must remember that thye Swarzschid solution is a mathematical solution, not an observation. We do not actually know what is inside the event horizon of a BH, nor can we be sure that the now accepted theories of gravitation are 100% correct.
In any case even if we answer ‘yes’ to both questions the BH is still a ‘limited object’. It has ‘infine density’ because all its mass is concentrated in one dimensionless point. So what matters in a BH is NOT its density, but the mass-energy that formed it in the first place and that causes the gravitational field.
Since the mass-energy is not infinite, even if ‘crushed’ into a dimensionless point, the BH is still a limited object with limited properties.

Rotating and charged black holes are a bit different (the mass-energy concentrates into a ring with sero volume) but the idea is the same.
So it has no time. It is like it exists in eternity.
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Well since a black hole was not always a black hole, ie it has a point in space-time when the star collapses into a BH, than NO it’s not “eternal”.

Whether a BH lasts forever there is also doubt as some think that BHs ‘evaporate’ (Hawking theorized this, see ‘hawking radiation’).
There is strong evidence of a super-massive black hole at the center of our own galaxy, see here. It doesn’t appear possible to explain the observations otherwise. Similarly other galaxies.
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Yes but all in the frame of some suppositions.

Sure the status quo in physics today is that black holes are real… it’s almost a dogma in modern gravitation theories. Actually so many scientists involve themselves with BHs or have them as part of their cosmological therories that denying BHs would practically destroy their life work.

… and no one wants that, certainly not scientists.

yet, there are theories that compete with General Relativity and there are theories that deny black holes even in GR.

So to say “It doesn’t appear possible to explain the observations otherwise” is not exactly true.

I am not advocating here that BHs are not real, since I have no problem with BHs.

I am just pointing out that they are not the super hardcore fact some people, even scientists, take them for.
 
Ismael said:
inocente;11124895:
There is strong evidence of a super-massive black hole at the center of our own galaxy, see here
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. It doesn’t appear possible to explain the observations otherwise. Similarly other galaxies.
Yes but all in the frame of some suppositions. …] I am just pointing out that they are not the super hardcore fact some people, even scientists, take them for.
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From the linked article:
Astronomers are confident that our own Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System, in a region called Sagittarius A*[12] because:


  1. *]The star S2 follows an elliptical orbit with a period of 15.2 years and a pericenter (closest distance) of 17 light-hours (1.8×1013 m or 120 AU) from the center of the central object.[13]

    *]From the motion of star S2, the object’s mass can be estimated as 4.1 million solar masses,[14][15] or about 8.2 × 1036 kg.

    *]The radius of the central object must be significantly less than 17 light-hours, because otherwise, S2 would either collide with it or be ripped apart by tidal forces. In fact, recent observations[16] indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus’ orbit.
    *]Only a black hole is dense enough to contain 4.1 million solar masses in this volume of space.

    The Max Planck Institute for Extraterrestrial Physics and UCLA Galactic Center Group[17] have provided the strongest evidence to date that Sagittarius A* is the site of a supermassive black hole,[12] based on data from ESO’s Very Large Telescope[18] and the Keck telescope.[19]

    So please give your alternative explanation of what is causing the observed tight orbits - it’s all too easy to ignore evidence, not so easy to explain it.
 
DaveBj said:
You are mistaking infinite density for infinite mass. A singularity means that the mass (the collapsing core of the supermassive star) has collapsed down into a point. A point has no dimensions, which means that it has no volume, or expressed mathematically, v=0. Density is mass (say, kilograms) divided by volume (cubic centimeters), or m/v, expressed in kg/cm^3. However, in a singularity m/v becomes m/0. Anytime you have a number divided by zero, the only result is infinity. Therefore, the density of the singularity at the center of the black hole is infinite.

However, the mass is not infinite, and therefore the black hole is not capable of sucking all the matter in the universe into it. A supermassive star has a finite (albeit huge) mass. Imagine a supermassive star with a stable planetary system around it. If all the star’s mass collapses into a singularity and forms a black hole*, the density of the singularity is infinite, but the mass is the same it was before. The planetary system was stable before, and it is still stable; the planets will continue to revolve around the black hole.

*This isn’t really the way that it happens; a lot of the stars mass is blown away. I put it this way just for illustration.
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I did not make the mistake of mixing up density and mass; on the contrary, I took it into account; it is the reason my point is valid. If a black hole had infinite density, the entire mass would be compacted into a single point. This is not the case; rather, all black holes have a substantial size, and some are estimated to be several to many miles in diameter.
 
dshix said:
I did not make the mistake of mixing up density and mass; on the contrary, I took it into account; it is the reason my point is valid. If a black hole had infinite density, the entire mass would be compacted into a single point. This is not the case; rather, all black holes have a substantial size, and some are estimated to be several to many miles in diameter.
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As long as we differentiate between the “black hole” and the singularity at its center, you are correct. The singularity does have infinite density; the black hole (the volume of space within the event horizon) does not.
 
DaveBj said:
If all the star’s mass collapses into a singularity and forms a black hole*, the density of the singularity is infinite, but the mass is the same it was before.
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Having coffee in the morning is good for the mind. My question is…how does it come to be that the galaxy orbits around a black hole in its center? Does this not happen because of the black hole’s mass? If it is the same as before…does this imply that the galaxy orbited first around a large star?

My science is not so strong. 😊
 
Porknpie said:
Having coffee in the morning is good for the mind. My question is…how does it come to be that the galaxy orbits around a black hole in its center? Does this not happen because of the black hole’s mass? If it is the same as before…does this imply that the galaxy orbited first around a large star?

My science is not so strong. 😊
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Yes, that was precisely my point. The mass is the same as it was before; it doesn’t increase to infinity just because it is suddenly infinitely dense.

With regard to Sagittarius A* (the black hole in the center of the galaxy, and similar black holes at the centers of other galaxies), astronomers and cosmologists are still trying to figure them out. It’s obviously more than the remains of a single large star; the one in our galaxy is estimated at more than four million times the mass of our sun.

Check out the Wiki article; it’s a good read and not too technical.
 
Does a galaxy swirl clockwise, or counterclockwise? Maybe galaxies are what form from individual “big bangs”, and then slowly swirl around a slow growing drain (black hole). Once the galaxy gets sucked in, the black hole explodes again and it starts all over. A galaxy is then like the breath of God.
 
Layp3rs0n said:
So a black hole is defined as a super massive star that has collapsed on itself to a point in which its density is infinite.
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Are their densities at actual infinity? If not then I don’t think you’ll want to use them as a metaphor for God.
 
None of this has anything at all to do with the Existence of God.

Linus2nd
 
There are numerous web sites available for people to learn about Galaxies ,Black holes,
and anything about astronomy that you can dream of… check universities for some of those have great Resources which are freely available… plus some Television Networks have Science departments, I look at ABC.net .au… it has links to anywhere on the planet that has an interest in Astronomy … Education, is what help the feeble mind needs…
 
ThinkingSapien said:
Are their densities at actual infinity? If not then I don’t think you’ll want to use them as a metaphor for God.
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General Relativity predicts a singularity at the center of a black hole, containing all the mass in one point. That would mean an infinite density, but infinities are anathema in physics so GR must be getting that prediction wrong. That’s probably because at that scale quantum physics rules, and no theory has yet been developed.

Imho it’s a mistake to try to think of God in terms of physics. Monsignor Lemaître, who developed big bang theory from GR, said:

He (the Christian researcher) knows that not one thing in all creation has been done without God, but he knows also that God nowhere takes the place of his creatures. Omnipresent divine activity is everywhere essentially hidden. It never had to be a question of reducing the supreme Being to the rank of a scientific hypothesis.
 
inocente said:
General Relativity predicts a singularity at the center of a black hole, containing all the mass in one point. That would mean an infinite density, but infinities are anathema in physics so GR must be getting that prediction wrong. That’s probably because at that scale quantum physics rules, and no theory has yet been developed.
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Since black holes don’t have infinite mass when ever I see something about infinite density it always raises a flag for me. Like you said, I think it’s a scale problem. Just as counting the number of atoms that could be strung from here to the Andromeda galaxy would appear to be infinite. But when viewed at different scales we see it’s a finite distance.
 
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