Role of particle's diameter in Quantum Mechanics

[SamRoss]

Does a particle's diameter affect anything in determining its position, momentum, energy, etc.? Does it play any role in Shrodinger's equation?

 

[Bill_K]

Introductory quantum mechanics deals with a single point particle that has no diameter.

 

[SamRoss]

Introductory quantum mechanics deals with a single point particle that has no diameter.

So when and how does the diameter come into play?

 

[Bill_K]

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.

 

[mquirce]

what is the density of mass in a point particle ?

 

[jtbell]

Undefined.

 

[mquirce]

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 ?

 

[SamRoss]

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?