I Notion of a zero dimensional point particle?

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1. Feb 23, 2017

Nickyv2423

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?

2. Feb 23, 2017

Simon Bridge

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.

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.

Last edited: Feb 23, 2017
3. Feb 23, 2017

mikeyork

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).

4. Feb 23, 2017

Simon Bridge

... or in the context of an interaction, or a confining potential, either of which could qualify as an observer.