Gravitation Force: Infinite Attraction & Separation

In summary, the conversation discusses the concept of gravitational force between two objects and whether it would be infinite if the distance between them is zero. It is stated that gravity is not a force and there is uncertainty in position in quantum mechanics that prevents the distance from becoming zero. It is also mentioned that the mass density of fundamental particles should be finite and that the electromagnetic force would overwhelm any experiment trying to test gravity at very small distances. The conversation also highlights the singularity of black holes and whether the charge density of particles is similar to the mass density.
  • #1
jobyts
227
64
If the distance between two objects is zero, won't there be infinite gravitational attraction force between them? How would the objects can get separated?
 
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  • #2
Gravity is't really a force and the amount of attraction between the objects wouldn't be infinate. Gravity can be defied with relatively little force.
 
  • #3
I'm talking about F = G*m1*m2/(d^2).

If d is zero, won't the F be infinite?
Or, is there a lower limit to d between two molecules/atoms, that eventually puts an upper limit to F?
 
  • #4
In the formula d is the distance between the centers of gravity. So even if two objects were touching their centers of gravity wouldn't be.
 
  • #5
jobyts said:
If d is zero, won't the F be infinite?
Congratulations jobyts, you just discovered a problem in classical physics.
When distances are very small (approaching zero in this case), you have to use quantum mechanics.
Since we don't have a working theory of quantum gravity, it's not quite clear how gravity will behave in this case.

jobyts said:
is there a lower limit to d between two molecules/atoms
Good question. In quantum mechanics, there is always uncertainty in position. With like-charged particles, the repulsive force will overwhelm all others, so the distance should never become zero. But with neutral or dissimilar charged particles, we have to consider further. When two dissimilar particles, (take proton and electron) are put together, you get an atom of hydrogen. The force of gravity cannot be infinite because the atom can be ionized (pulling the electron away). I would speculate that the uncertainty in position of the electron keeps the distance non-zero. I don't think two neutral particles (two neutrons) can occupy the same space because they are fermions, and thus obey the Pauli exclusion principle.
 
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  • #6
gendou2 said:
Congratulations jobyts, you just discovered a problem in classical physics. When distances are very small (approaching zero in this case), you have to use quantum mechanics.

That's wouldn't be necessary, nor asuccessful endeavor, without a theory of quantum gravity. It would be sufficient, to eliminate infinites, that mass density be finite.

I don't know of any infinitely dense masses. Newtonian gravity will suffice in avoiding infinities in force and energy, in this case, if you don't assume infinite densities as a premise.
 
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  • #7
Phrak said:
It would be sufficient, to eliminate infinites, that mass density be finite.
Good point, Phrak.
Have the mass density of the fundamental particles been measured?
I have seen fundamental particles treated as point-like particles of infinite density.
I suspect this is not how they really are, and that they should have finite density.
Also, it would be interesting to find out wether the charge density looks like the mass density (for particles that have charge).

Phrak said:
I don't know of any infinitely dense masses.
The singularity in a black hole? :)

EDIT
I just learned that the charge density distribution of the neutron is not constant zero.
So, in testing gravity between two particles approaching zero distance using protons, electrons, or even neutrons, the electromagnetic force will overwhelm the experiment.
http://www.terra.es/personal/gsardin/news13.htm
 
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  • #8
gendou2 said:
Good point, Phrak.
Have the mass density of the fundamental particles been measured?
I have seen fundamental particles treated as point-like particles of infinite density.
I suspect this is not how they really are, and that they should have finite density.
Also, it would be interesting to find out wether the charge density looks like the mass density (for particles that have charge).

The singularity in a black hole? :)

I missed that one. (But is the map the territory?)

That's not a bad question. In quntum mechanics, a measurement can localize a particle's postion, but does locaize it's mass?
 

What is Gravitation Force?

Gravitation Force is a fundamental force of nature that describes the attraction between two objects with mass. It is responsible for keeping planets in orbit around the sun and objects on Earth from floating away into space.

Why is Gravitation Force considered an infinite attraction?

Gravitation Force is considered infinite because it is always present between any two objects with mass, regardless of the distance between them. This means that no matter how far apart two objects are, there will always be a gravitational pull between them.

What causes Gravitation Force?

Gravitation Force is caused by the mass and distance between two objects. The greater the mass of the objects and the closer they are to each other, the stronger the gravitational force.

How does Gravitation Force affect objects?

Gravitation Force affects objects by pulling them towards each other. This can result in objects being pulled into orbit, falling towards a larger object, or being held together in a stable structure, such as a planet or star.

What is the difference between Gravitation Force and Separation?

Gravitation Force and Separation are two opposing forces that act on objects with mass. Gravitation Force pulls objects towards each other, while Separation pushes objects away from each other. These forces are constantly in balance, and the strength of each determines the overall motion of the objects.

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