Are Field Boundaries Absolute in Space?

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Discussion Overview

The discussion explores the nature of field boundaries in the context of electrical charge and magnetic polarity, questioning whether these boundaries are absolute or "fuzzy." Participants examine the implications of overlapping fields and the experience of net fields at various points in spacetime.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that while macroscopic boundaries (like skin) may seem absolute, at a microscopic level, boundaries are "fuzzy" and cannot be precisely defined.
  • Another participant states that fields can overlap, referencing the principle of superposition as a characteristic of linear systems.
  • A question is raised about whether a point in space can simultaneously exist in regions of both positive and negative charge.
  • It is confirmed that one can experience a net field, which is the sum of overlapping fields, rather than distinct positive or negative charges at a single point.
  • A participant elaborates that at large distances, the net potential experienced from an atom is weak due to cancellation of fields from positive and negative charge clouds.
  • There is a discussion about the vector nature of fields, emphasizing that fields are not inherently positive or negative but have direction and magnitude.
  • One participant explains that field lines are merely a representation and do not indicate physical boundaries.

Areas of Agreement / Disagreement

Participants express varying views on the nature of field boundaries, with some agreeing that fields can overlap and others questioning the implications of experiencing a net field. The discussion remains unresolved regarding the absolute nature of field boundaries.

Contextual Notes

Participants acknowledge the complexity of defining boundaries in fields, with references to the vector nature of fields and the principle of superposition. There are unresolved aspects regarding how fields interact and the implications of their overlapping characteristics.

spacebear2000
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My understanding is that, while at a macroscopic level, my skin may seem like an absolute boundary between my interior and exterior, at a microscopic level, it is full of wholes--we cannot draw a line or arc that represents and absolute boundary between my interior and exterior at a given point in time. I can generalize a skin-boundary for myself, but only in a "fuzzy" way.

Are fields of electrical charge and magnetic polarity dissimilar to my body in this way? In other words, is the boundary between a positively charged field and a negatively charged field "fuzzy," or do they never interpenetrate or overlap at a given point in spacetime? If your observational capacity is in the center of a negatively charged field and heads out in a given direction towards a positively charged field, what would passing the threshold between the two field charges be like?
 
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Fields do overlap. This is called the principle of superposition and is a general characteristic of all systems which are called linear.
 
So if I'm a point at coordinates x,y,z at time t, I can be in a region of positive and negative charge simultaneously?
 
That's right, but you only experience the 'net' field, which is the sum of the two.
 
If I only experience the net field, doesn't that mean I would only experience positive, negative, or neutral charge at any given point in spacetime?
 
spacebear2000 said:
If I only experience the net field, doesn't that mean I would only experience positive, negative, or neutral charge at any given point in spacetime?

Look at an atom from large distances: you experience a very weak net potential U(r) because the fields from the positive and negative charge clouds in atom cancel each other at large distances. Negative and positive ions create long-tailed Coulomb potentials of different signs.
 
spacebear2000 said:
If I only experience the net field, doesn't that mean I would only experience positive, negative, or neutral charge at any given point in spacetime?
The field is not positive or negative, it is a vector which points in some direction with some magnitude at each point in space.
 
spacebear2000 said:
If I only experience the net field, doesn't that mean I would only experience positive, negative, or neutral charge at any given point in spacetime?

So if you think of labeling the staring end of the field lines positive and the terminal end negative and you have two fields overlapping, considering a point where the fields overlap with the same magnitude but facing the exactly the opposite directions (180 degrees for 2 angle measurements in 3d) the net field you experience is 0. Otherwise add the components of the fields in each direction since they are vectors and overall the magnitude that you experience may be less or more than the magnitude of the either of the fields alone.

Note: Field lines are just a way to represent a field on paper and are not representing any sort of physical boundary.
 
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