What is a particle in quantum mechanics?

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Discussion Overview

The discussion revolves around the concept of what constitutes a particle in quantum mechanics, exploring various definitions and interpretations. It includes theoretical perspectives and conceptual clarifications.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant suggests that a particle can be understood as something detected by a particle detector, which manifests as a dot on a screen.
  • Another participant describes a particle as a discrete excitation of a quantum field, characterized by the eigenvalues of conserved operators like charge, mass, and spin, and notes that particles are often well-localized in space.
  • A further contribution references a definition by E.P. Wigner, framing a particle as a quantum state in the (rigged) Hilbert space that carries an irreducible representation of the universal covering group of the restricted Poincare group.

Areas of Agreement / Disagreement

Participants present multiple competing views on the definition of a particle, indicating that the discussion remains unresolved with no consensus reached.

Contextual Notes

Definitions provided depend on specific interpretations of quantum mechanics and may involve complex mathematical frameworks that are not fully explored in the discussion.

arupel
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I would imagine that there are different viewpoints of what a particle is in quantum mechanics. Is it possible to get a summary of what they are?
 
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Something that is detected by a particle detector, i.e. something that shows up as a dot on a screen, or some such.
 
A discrete excitation of a quantum field which is characterized by the eigenvalues of some set of conserved operators (e.g. charge, mass, and spin). They are often, but not necessarily, well-localized in space.
 
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The definition in post#3 reminds me of the famous one by E.P. Wigner which can be recast as: A particle is a quantum state in the (rigged) Hilbert space which carries an irreducible representation of the universal covering group of the restricted Poincare group.
 

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