No Potential Energy due to Sphere of Mass?

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Discussion Overview

The discussion revolves around the concept of potential energy in relation to spheres of mass and charge. Participants explore the differences in energy considerations when assembling charged spheres versus massive spheres, questioning whether mass has intrinsic potential energy in the classical sense.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants argue that building a sphere of charge requires work due to repulsion, implying it has intrinsic potential energy, while a sphere of mass does not require energy to form under gravity.
  • Others contend that while mass only attracts, this does not explain the existence of clumps of mass compared to clumps of charge.
  • One participant suggests that gravitational potential differences lead to clumping of mass, while electric charges require external stabilization.
  • There is a discussion about the nature of charge, with some participants questioning the concept of continuous charge distributions versus discrete charges.
  • Concerns are raised about mixing discrete (quantum) and continuous (classical) ideas in the context of charge and potential energy.
  • Another participant introduces the notion that energy is released during the natural assembly of mass, relating it to gravitational potential energy and the concept of a gravity well.

Areas of Agreement / Disagreement

Participants express differing views on whether mass has intrinsic potential energy and the implications of gravitational versus electrostatic interactions. The discussion remains unresolved with multiple competing perspectives on the nature of energy in mass and charge.

Contextual Notes

Participants reference classical electrostatics and the distinction between discrete and continuous charge distributions, indicating a need for clarity in definitions and assumptions. The discussion also touches on the implications of gravitational potential energy being negative and the conventions surrounding it.

FallenApple
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So we all know that it takes work to build up a sphere of charge by taking charge from infinity and piling it up into a sphere. Since the sphere wants to break apart under repulsion, its like a spring. It has intrinsic potential energy.However it doesn't seem the case with a sphere of mass, with no charge. It takes energy to disassemble it. But no energy to build it, since it happens naturally under gravity.

What does this all mean? Does this mean that in the classical sense, constructs of mass has no energy?
 
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FallenApple said:
So we all know that it takes work to build up a sphere of charge by taking charge from infinity and piling it up into a sphere. Since the sphere wants to break apart under repulsion, its like a spring. It has intrinsic potential energy.However it doesn't seem the case with a sphere of mass, with no charge. It takes energy to disassemble it. But no energy to build it, since it happens naturally under gravity.

What does this all mean? Does this mean that in the classical sense, mass itself has no energy?

Masses only attract, there is no repulsion in Gravity.
 
lychette said:
Masses only attract, there is no repulsion in Gravity.
Does that explain why clumps of masses exists and clumps of charge doesn't?
 
FallenApple said:
Does that explain why clumps of masses exists and clumps of charge doesn't?
No
 
But masses will clump up naturally due to gravity. Solid electric spheres of same charges needs external something to stablize it. But mass doesn't.
 
FallenApple said:
But masses will clump up naturally due to gravity. Solid electric spheres of same charges needs external something to stablize it. But mass doesn't.

What is the diameter of your 'solid' sheers?
 
lychette said:
What is the diameter of your 'solid' sheers?
Lets just say large enough so that you don't have to go quantum or relativistic.
 
FallenApple said:
Lets just say large enough so that you don't have to go quantum or relativistic.

Mmmm...you are describing where not to go...what about 100mm diameter. Have you come across such a solid electric charge?
 
lychette said:
Mmmm...you are describing where not to go...what about 100mm diameter. Have you come across such a solid electric charge?

No i have not.
 
  • #10
FallenApple said:
No i have not.

Well I have a 100mm diameter hemisphere in front of me that needs charging.
 
  • #11
lychette said:
Well I have a 100mm diameter hemisphere in front of me that needs charging.
Oh I get it. So you just need to induce a potential difference and clumps of charge will form in a conductor. And this can occur naturally.

Is the energy put into create the potential difference form a clump of charge Q a conductor the same as the potential energy of a solid continuous sphere of charge Q?
 
  • #12
FallenApple said:
Oh I get it. So you just need to induce a potential difference and clumps of charge will form in a conductor. And this can occur naturally.

Is the energy put into create the potential difference form a clump of charge Q a conductor the same as the potential energy of a solid continuous sphere of charge Q?

My hemisphere relies on gravitational potential difference to form a clump.
What do you mean by a 'continuous' sphere of charge?... Charge consists (as far as I know) of discrete entities (1.6x 10^-19)... Not a continuum.
 
  • #13
lychette said:
My hemisphere relies on gravitational potential difference to form a clump.
What do you mean by a 'continuous' sphere of charge?... Charge consists (as far as I know) of discrete entities (1.6x 10^-19)... Not a continuum.
I'm talking about classical electrostatics where there can be charges that are continuous. Besides, aren't electrons so small that they can be considered as differentials? e.g dq.
 
  • #14
FallenApple said:
I'm talking about classical electrostatics where there can be charges that continuous. Besides, aren't electrons so small that they can be considered as differentials? e.g dq.

You are confused about discrete and continuous ! Earlier you refer to 'clumps' of charge in my hemispherical Container And now you are using classical ideas to refer to continuous Charges. You cannot mix up 'discrete' (quantum) ideas with 'continuous' (classical) ideas easily.
'Differentials' are a mathematical idea as are 'integrals'
FallenApple said:
I'm talking about classical electrostatics where there can be charges that are continuous. Besides, aren't electrons so small that they can be considered as differentials? e.g dq.
FallenApple said:
I'm talking about classical electrostatics where there can be charges that are continuous. Besides, aren't electrons so small that they can be considered as differentials? e.g dq.
 
  • #15
lychette said:
You are confused about discrete and continuous ! Earlier you refer to 'clumps' of charge in my hemispherical Container And now you are using classical ideas to refer to continuous Charges. You cannot mix up 'discrete' (quantum) ideas with 'continuous' (classical) ideas easily.
'Differentials' are a mathematical idea as are 'integrals'
I know that continuous charges do not literally exist. But if I take a trillions of electrons and put them together, would it not have a net charge that is numerically similar to one that is evaluated with integrals?
 
  • #16
FallenApple said:
I know that continuous charges do not literally exist. But if I take a trillions of electrons and put them together, would it not have a net charge that is numerically similar to one that is evaluated with integrals?

You have forgotten your original question.
The answer I gave is that masses do not repel...has your original question been answered? How will your current question help you get to grips with your original question?... Are you any wiser?
 
  • #17
FallenApple said:
It takes energy to disassemble it. But no energy to build it, since it happens naturally under gravity.
Energy is released during the process (exactly the same amount it would take to disassemble it later). For example a third of the heat coming out from Earth core is primordial heat left over from the times of Earth formation. This is also how stars ignite.
Objects closer to the gravitating mass have less potential energy that those further away. By convention potential energy is assumed to be 0 for objects 'at infinity'. This makes gravitation potential energy negative everywhere. Thus the notion of gravity well we live in.
But for practical purposes you can place the origin anywhere you like.You you set 0 to be at sea level, objects above it will have positive energy, below it - negative.
 

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