What separates one particle from another?

  • Context: Graduate 
  • Thread starter Thread starter JDude13
  • Start date Start date
  • Tags Tags
    Particle
Click For Summary

Discussion Overview

The discussion centers around the distinctions between particles based on their wavefunctions, energy, mass, and momentum. Participants explore the implications of the energy relation E=hv, particularly in the context of particles with mass versus massless particles, and how these factors contribute to identifying different particles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how to differentiate between a slow, heavy particle and a light, fast particle if each particle's wavefunction is related to its energy (E=hv).
  • Another participant argues that E=hv is applicable only to massless particles like photons, suggesting the initial question is inconsistent with this equation.
  • A participant seeks clarification on the correct equation for particles with mass and questions the validity of their original inquiry regarding particle identity.
  • One participant acknowledges a misunderstanding regarding the interpretation of 'v' in the equation, clarifying that it refers to frequency, not velocity.
  • Another participant introduces the concept of momentum, stating that particles of differing mass but the same energy will have different momentum.
  • A participant challenges the focus on energy by stating that the equation does not address momentum directly and requests an explanation of how momentum relates to the discussion.
  • One participant reiterates the need to measure mass and velocity independently, noting their relationship to energy and momentum through specific equations.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the energy relation E=hv to particles with mass, leading to confusion and debate regarding the role of momentum and the correct equations to use. No consensus is reached on these points.

Contextual Notes

There are unresolved assumptions regarding the definitions of energy and momentum in the context of different particle types, as well as the implications of the equations discussed. The discussion reflects a mix of interpretations and clarifications that have not been fully settled.

JDude13
Messages
95
Reaction score
0
If each particle's wavefunction is directly related to it's energy (E=hv), how cn we tell the difference between a slow, heavy particle and a light, fast particle?
 
Physics news on Phys.org
The energy relation that you provided (E=hv) works only for massless particles, like the photon, which always moves at the speed of light. Therefore your question isn't quite consistent with the equation.
 
Okay... umm... What is the equation for particles with mass? and is my question still valid?

What keeps particles with different types but simmilar levels of energy from being the same particle?
 
oops, your equation is valid for all particle types. My mistake. I mistook your 'v' as somehow being related to velocity instead of the frequency.

Anyway, the answer to your question is that the momentum is different for particles of differing mass but with same energy.
 
TriTertButoxy said:
The energy relation that you provided (E=hv) works only for massless particles, like the photon, which always moves at the speed of light. Therefore your question isn't quite consistent with the equation...
..oops, your equation is valid for all particle types. My mistake. I mistook your 'v' as somehow being related to velocity instead of the frequency...
How do you come to that conclusion? This is confusing energy relations, which can be found by looking under the heading "The relativistic energy-momentum equation" at http://en.wikipedia.org/wiki/Mass_in_special_relativity, with the de Broglie relation p = hf/c (I here use f for frequency). There is a universal relationship between particle momentum p and frequency, not particle energy E and frequency!
 
Last edited:
TriTertButoxy said:
oops, your equation is valid for all particle types. My mistake. I mistook your 'v' as somehow being related to velocity instead of the frequency.

Anyway, the answer to your question is that the momentum is different for particles of differing mass but with same energy.

But the equation doesn't say anything about momentum; just energy.

Could you please explain to me where momentum comes in?
 
JDude13 said:
If each particle's wavefunction is directly related to it's energy (E=hv), how cn we tell the difference between a slow, heavy particle and a light, fast particle?

This only holds for eigenstates of the Hamiltonian. It says nothing about mass m and velocity v. The latter quantities must be measured independently and are related to the energy and momentum p by (E/c)^2=(mc)^2+p^2 and p=mv.
 

Similar threads

Graduate Scattering cross section between charged particle and magnetic moment
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Three Plus Anti-symmetric Particles
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad What is the true nature of microscopic particles when not interacting?
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Can you tell the difference between two neutrons in an alpha particle?
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Importance of Densities in QFT
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad The claymath 4-d QFT problem and virtual particles (as an example)
  • · Replies 36 ·
2
Replies
36
Views
4K
Undergrad Question regarding quantum mechanics from relativity perspective
  • · Replies 3 ·
Replies
3
Views
1K
Undergrad Quantum fluctuations & 'virtual particles'
  • · Replies 10 ·
Replies
10
Views
5K
Graduate Can particles appear and disappear "with" a cause?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Indistinguishable particles in separate boxes
  • · Replies 9 ·
Replies
9
Views
2K