What exactly is meant by the word "particle"

  • Context: High School 
  • Thread starter Thread starter Enjamiering
  • Start date Start date
  • Tags Tags
    Particle
Click For Summary

Discussion Overview

The discussion revolves around the meaning of the term "particle" in various contexts, particularly in classical physics versus quantum mechanics. Participants explore the implications of this terminology and its application to different types of particles, including point masses and subatomic particles.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that in classical physics, a particle is often considered an ideal point mass, while in quantum mechanics, the term encompasses a broader range of entities, including electrons and photons, which do not conform to the classical definition.
  • There is a suggestion that the term "particle" has evolved from "material points" or "point masses," indicating a shift in terminology over time.
  • One participant expresses concern that referring to photons as particles conflates them with massive particles, arguing that their properties are sufficiently distinct to warrant a different term.
  • A later reply questions the characterization of particles in quantum field theory (QFT) as "not ideal point masses," prompting further exploration of what this distinction entails.
  • Another participant defines a "classical pointlike particle" as a macroscopic object described by a single geometrical point, while suggesting that elementary particles like electrons require a quantum theoretical description.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of the term "particle" for various entities, particularly photons versus massive particles. The discussion remains unresolved regarding the implications of this terminology and the distinctions between classical and quantum descriptions.

Contextual Notes

Limitations include the potential ambiguity in definitions of "particle" across different physical theories and the unresolved nature of how these definitions apply in various contexts.

Enjamiering
Messages
4
Reaction score
0
I was browsing through the content section of my book and see the word particle mentioned many times in many chapters. Each time I read I start thinking that maybe it can mean more than subatomic particles.
I commonly deal with particles with point masses and things of the sort and I'm not sure exactly what it could mean in layman's terms
 
Physics news on Phys.org
Enjamiering said:
I was browsing through the content section of my book and see the word particle mentioned many times in many chapters. Each time I read I start thinking that maybe it can mean more than subatomic particles.
I commonly deal with particles with point masses and things of the sort and I'm not sure exactly what it could mean in layman's terms

In classical physics, a particle is an ideal point mass.

In quantum mechanics and especially quantum field theory, the word "particle" is used, but it means something very different - electrons, photons, quarks, and all the rest of the subatomic zoo are not ideal point masses. There's no ambiguity or unclarity in the quantum mechanical description, but it doesn't match our intuition about how objects should behave.
 
  • Like
Likes   Reactions: Enjamiering
Enjamiering said:
I was browsing through the content section of my book and see the word particle mentioned many times in many chapters. Each time I read I start thinking that maybe it can mean more than subatomic particles.
I commonly deal with particles with point masses and things of the sort and I'm not sure exactly what it could mean in layman's terms
We used to speak about material points or point masses, now "particle" is frequently used instead.
 
All the above is perfectly ok thinking. The problem arose when 'they' started calling photons 'particles', which lumped them in with particles with mass. The properties of photons are, to my mind, sufficiently different for them to deserve a different word. I guess it's too late to do anything about that, unfortunately.
 
  • Like
Likes   Reactions: vanhees71
Nugatory said:
In classical physics, a particle is an ideal point mass.

In quantum mechanics and especially quantum field theory, the word "particle" is used, but it means something very different - electrons, photons, quarks, and all the rest of the subatomic zoo are not ideal point masses. There's no ambiguity or unclarity in the quantum mechanical description, but it doesn't match our intuition about how objects should behave.
I'd say an electron in qft is a pointlike particle, having no internal stucture. What do you mean precisely by 'not ideal point masses'?

Edit never mind, I just read

http://physics.stackexchange.com/questions/163691/the-concept-of-particle-in-qft
 
I'd define a "classical pointlike particle" as a macroscopic object for which it is in some given context sufficient to be described just by the position of one geometrical point related to this object. Usually it's convenient to choose the center of mass (or in relativistic physics the center of energy) as this point. E.g., for the description of the motion of the Earth around the Sun, it is not too wrong to describe the Earth as a "point particle".

Elementary particles like electrons are usually not describable as classical point particles, because they must be described quantum theoretically.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 14 ·
Replies
14
Views
4K
  • · Replies 25 ·
Replies
25
Views
5K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 41 ·
2
Replies
41
Views
5K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 23 ·
Replies
23
Views
3K