Notion of a zero dimensional point particle?

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Discussion Overview

The discussion revolves around the concept of a zero-dimensional point particle, particularly in the context of quantum mechanics and its implications for the properties of fundamental particles. Participants explore whether the notion of zero-dimensionality is literal or figurative, and how it relates to the spatial properties of particles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether the term "zero-dimensional" is to be taken literally or figuratively, suggesting that it may represent a mathematical model rather than a physical reality.
  • One participant notes that the "size" of a particle is context-dependent and described by its cross-section, which varies with interactions.
  • Another viewpoint suggests that a particle's properties, such as charge and mass, could be spread over a finite volume but may appear to be localized when measured, potentially described by a Gaussian distribution with a small standard deviation.
  • Some participants argue that intrinsic spatial properties of a particle are only meaningful in relation to an observer or an interaction, implying that location and size are not inherent to the particle itself.
  • There is a contention regarding the concept of a "zero-dimensional plane," with one participant asserting that such a term is contradictory, while others clarify that a zero-dimensional point can exist within higher-dimensional spaces.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of zero-dimensionality and the implications for the properties of particles, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

Some discussions hinge on the definitions of dimensionality and the context in which spatial properties are considered, which may not be universally agreed upon.

Nickyv2423
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When we say a fundamental particle is 0 dimensional, is that literal or figurative?
Is it physically possible that a particle has it's properties (like charge, mass) spread out in a finite volume, but can be "shrunk" to increasingly small volumes when we measure it?
 
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Nickyv2423 said:
When we say a fundamental particle is 0 dimensional, is that literal or figurative?
It is a mathematical model. Strictly speaking it means that the classical extent of the particle in space has no clear meaning in QM.
The "size" of a particle depends on the interaction and is given by a quantity called the cross-section.
The location of the particle in space is given by a probability distribution which tells you the chance of detecting the particle within a particular volume within a particular time period.

Is it physically possible that a particle has it's properties (like charge, mass) spread out in a finite volume, but can be "shrunk" to increasingly small volumes when we measure it?
The statistics of the particle may, in principle, be arbitrarily tightly located - yes.
For example: if the position is described by a Gaussian distribution, then the standard deviation of that distribution may be arbitrarily small.
 
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My way of looking at it is that the particle has no intrinsic spatial properties. Spatial properties like location (and even size), for instance, are meaningful only in another entity's context (such as an observer).
 
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mikeyork said:
My way of looking at it is that the particle has no intrinsic spatial properties. Spatial properties like location (and even size), for instance, are meaningful only in another entity's context (such as an observer).
... or in the context of an interaction, or a confining potential, either of which could qualify as an observer.
 
MonteCristo said:
There is absolutely no way in which the particle can exist in a zero dimensional plane
Well, that's true but not for the reason you think.

Your "zero dimensional plane" is an oxymoron - a plane consists of two dimensions.
But that's not what the OP is talking about.

MonteCristo said:
as it needs an actual base of existence in a dimension,
Can a two-dimensional plane inhabit three-dimensional space? Sure. The plane that divides my pretty neighbour's property from mine.
Can a one-dimensional line inhabit three-dimensional space? Sure. The line of sight between my land-scope and my neighbour's kitchen window. Anything that intersects that line intersects my sight line.
Can a zero-dimensional point inhabit a three-dimensional plane? Sure. The focus of the eyepiece that I'm using to ensure my neighbour is safe from creeps.
 
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