Why do black holes have infinite density, mass, and gravity?

In summary, the conversation discussed the concept of black holes and the confusion surrounding their characteristics, such as infinite density, mass, and gravity. There was also a mention of a scientist, Michio Kaku, who may have caused some confusion by stating that black hole singularities have infinite density and gravity, without clarifying that this only applies to the singularity itself and not the entire black hole. The conversation also touched on the disagreement among scientists on certain fundamental ideas about the Universe and the challenge of understanding complex scientific concepts for laymen.
  • #1
science_rules
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If stars have finite mass, gravity, and density, why does a black hole have infinite density, mass, and gravity and why doesn't it attract everything around it with such infinite gravity? Also, with infinite density, why are black holes all different sizes?
 
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  • #2
science_rules said:
...why does a black hole have infinite density, mass, and gravity...
As far as we can tell, black holes don't have any of those characteristics.
 
  • #3
In a science documentary, Michio Kaku mentioned that the singularity of black holes have infinite density and infinite gravity. How can laymen expect to learn anything or trust scientists if what some scientists say is not what other scientists believe and scientists never agree with each other about fundamental ideas about the Universe? If what he said is true, it seems then that scientists cannot agree with each other, either that or scientists just make stuff up even if it doesn't make any sense. Same with string theory.
 
  • #4
science_rules said:
In a science documentary, Michio Kaku mentioned that the singularity of black holes have infinite density and infinite gravity.
There is some debate on PF as to what "the singularity" means, however Kaku was almost certainly referring to a finite mass in zero volume. In either case, since we can't ever go and check, that doesn't impact what a black hole looks like to us (a region of space with a finite volume, finite mass and finite gravitational field). There is no debate about that. So does that clear it up...?
How can laymen expect to learn anything or trust scientists if what some scientists say is not what other scientists believe and scientists never agree with each other about fundamental ideas about the Universe? If what he said is true, it seems then that scientists cannot agree with each other, either that or scientists just make stuff up even if it doesn't make any sense.
Sorry, but the misunderstanding there is yours; You extrapolated something beyond what he said.
[also, a link would help...]
 
  • #5
science_rules said:
infinite gravity
Why does an electron have infinite electric field at zero distance?
 
  • #6
russ_watters said:
There is some debate on PF as to what "the singularity" means, however Kaku was almost certainly referring to a finite mass in zero volume. In either case, since we can't ever go and check, that doesn't impact what a black hole looks like to us (a region of space with a finite volume, finite mass and finite gravitational field). There is no debate about that. So does that clear it up...?

Sorry, but the misunderstanding there is yours; You extrapolated something beyond what he said.
[also, a link would help...]
That makes no sense. If Kaku meant that, he should have said so instead of making it confusing and misleading for the laymen. Saying a black hole has infinite density is not the same as saying finite mass in zero volume.

<< Mentor Note -- Insult removed from post >>
 
  • #7
Pay attention to what was said: singularities have infinite density and infinite gravity. This is not the same as black holes having those characteristics. Nor was anything said about infinite mass.

Black hole singularities have 0 volume, so any finite mass they might have will net infinite density, and infinite gravity (since you can get infinitely close to the central mass).

Black holes themselves are regions surrounding the singularity, within which escape velocity is greater than c. Since those regions have finite volume, their density and gravity are finite too.

The extent of that region is dependent on mass encompassed within, so it will vary with varying mass.
 
  • #8
science_rules said:
That makes no sense. If Kaku meant that, he should have said so instead of making it confusing and misleading for the laymen. Saying a black hole has infinite density is not the same as saying finite mass in zero volume.
Yes, actually it is:
What happens to "d" in the following function as "v" approaches zero?
d=m/v

And please slow your roll; I'm trying to help.
 
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  • #9
russ_watters said:
Yes, actually it is:

What happens to "d" in the following function as "v" approaches zero?
d=m/v

And please slow your roll.
You beat me to it...
 
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  • #10
science_rules said:
How can laymen expect to learn anything or trust scientists if what some scientists say is not what other scientists believe
You now understand why most physicists roll their eyes at the mention of Michio Kaku...
 

Related to Why do black holes have infinite density, mass, and gravity?

1. Why do black holes have infinite density?

The infinite density of black holes is a result of the intense gravitational force that causes matter to collapse into an infinitely small point called a singularity. This singularity has infinite density because all the mass of the black hole is concentrated in an infinitely small space.

2. How can black holes have infinite mass?

The mass of a black hole is determined by the amount of matter that has collapsed into the singularity. As more matter falls into the black hole, its mass increases. Since the singularity has infinite density, it can hold an infinite amount of mass, resulting in the black hole having infinite mass.

3. Why do black holes have such strong gravity?

The strength of gravity is directly proportional to the mass of an object. Since black holes have infinite mass, they also have an infinite amount of gravitational force. This intense gravitational pull is what makes it impossible for anything, including light, to escape from a black hole's event horizon.

4. Can anything escape from a black hole's infinite gravity?

No, once an object crosses the event horizon of a black hole, it is impossible for it to escape due to the infinite gravity. The escape velocity required to leave the event horizon is greater than the speed of light, which is why even light cannot escape from a black hole.

5. How do we know that black holes have infinite density, mass, and gravity?

Scientists use various methods, such as studying the effects of a black hole's gravity on surrounding objects, to indirectly observe and measure the properties of black holes. The theory of general relativity also predicts the existence of black holes and their properties, and so far, all observations have confirmed these predictions.

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