Role of particle's diameter in Quantum Mechanics

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Discussion Overview

The discussion centers around the role of a particle's diameter in quantum mechanics, particularly in relation to its position, momentum, and energy. Participants explore whether diameter is relevant in the context of Schrödinger's equation and the implications for different types of particles, including elementary particles and those with internal structures.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question whether a particle's diameter affects its physical properties like position and momentum, particularly in the context of Schrödinger's equation.
  • Others note that introductory quantum mechanics typically considers particles as point-like, without diameter.
  • A participant suggests that diameter may become relevant when discussing particles with internal structures, such as molecules or atomic nuclei, which may involve additional energy contributions from internal degrees of freedom.
  • One participant inquires about the concept of mass density in point particles, which is met with an undefined response.
  • Another participant raises questions about the relationship between point particles and black holes, as well as the significance of Planck's constant in quantum mechanics.
  • There is a reiteration that elementary particles are generally considered point particles, but the internal structure of composite particles like protons, which consist of quarks, may require a different approach.

Areas of Agreement / Disagreement

Participants express differing views on the relevance of diameter in quantum mechanics, with some asserting that it is negligible for elementary particles while others argue it may be significant for composite particles. The discussion remains unresolved regarding the implications of diameter and the nature of point particles.

Contextual Notes

Limitations include the undefined nature of mass density in point particles and the lack of clarity on how diameter influences quantum mechanical properties in various contexts.

SamRoss
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Does a particle's diameter affect anything in determining its position, momentum, energy, etc.? Does it play any role in Shrodinger's equation?
 
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Introductory quantum mechanics deals with a single point particle that has no diameter.
 
Bill_K said:
Introductory quantum mechanics deals with a single point particle that has no diameter.

So when and how does the diameter come into play?
 
Elementary particles are, to our best knowledge, point particles. Only if you're dealing with an object that has internal structure, like a molecule, or an atomic nucleus, does this not apply. In such cases you may need to consider contributions to the energy from the internal degrees of freedom: rotation, vibration, or other modes of excitation.
 
what is the density of mass in a point particle ?
 
Undefined.
 
Let say that the particle has a geodesic. It clear that geodesic of a particle : ( G*M / R ) is it infinity. I am a lay man . i ask: is it point particle a so called black hole?
Why the quantum theoretical mecanics has as the base of the theory the Plank constant "h" and neglect all other Plank constants? And why "h" is called energy when it has the unity E / T ?
 
Bill_K said:
Elementary particles are, to our best knowledge, point particles. Only if you're dealing with an object that has internal structure, like a molecule, or an atomic nucleus, does this not apply. In such cases you may need to consider contributions to the energy from the internal degrees of freedom: rotation, vibration, or other modes of excitation.

The internal structure of protons, for example, would need to be looked at because they are made up of quarks. Is this correct?
 

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