Particles more fundamental than fields

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Discussion Overview

The discussion revolves around the conceptual status of particles and fields in quantum field theory (QFT). Participants explore whether particles can be considered more fundamental than fields, referencing various texts and theories, including works by Nima Arkani-Hamed and Steven Weinberg. The scope includes theoretical implications and philosophical considerations regarding the nature of particles and fields.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants cite Nima Arkani-Hamed's paper suggesting that constraints in QFT arise from treating fields as auxiliary to more fundamental particles.
  • Others argue that the traditional view in QFT literature positions fields as more fundamental than particles, with particles being excitations of these fields.
  • One participant questions the clarity of the original question, suggesting that without empirical agreement on what is fundamental, the discussion may lack scientific grounding.
  • Another participant notes that particles only exist in perturbation theory, raising doubts about the possibility of them being more fundamental than fields.
  • Some participants acknowledge that while Schwartz's QFT book does not promote the idea of particles being more fundamental, the notion is still considered a legitimate area for further investigation.
  • A reference to old-fashioned S-matrix theory is made, which attempted to derive particle behavior without relying on field theory, suggesting alternative approaches to the fundamental nature of particles.
  • A participant mentions an upcoming three-volume book by E. Stefanovich that promotes the idea of particles as primary ingredients, with quantum fields being secondary.

Areas of Agreement / Disagreement

Participants express multiple competing views on the fundamental nature of particles versus fields. There is no consensus on whether particles are more fundamental than fields, and the discussion remains unresolved.

Contextual Notes

Participants highlight the philosophical implications of defining "fundamental" in a scientific context, as well as the dependence on specific theoretical frameworks and interpretations in QFT.

Lapidus
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In this Nima Arkani-Hamed paper on page 5 I found the sentence:

These constraints are an artifact of using fields as auxiliary objects to describe the interactions of the more fundamental particles.

In Schwartz's QFT book I also get away with the impression that the Poincaré irreps (i.e. particles) are more fundamental and field representations are just secondary.

But this view seems to be contrary with most other (older) QFT books and notes that I came across, where particles are just excitations of the fundamental quantum fields.

My question: is there are "conceptual shift" taking place towards an understanding that particles are more fundamental than fields?
 
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This is not a well-defined question. Until there is an empirical way for two people to agree on the fundamentalness of something, it is not a scientific question and I predict that this thread, like the many that have come before it, will circle the philosophical drain until the Mentors decide to put it out of its misery.
 
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Lapidus said:
In Schwartz's QFT book I also get away with the impression that the Poincaré irreps (i.e. particles) are more fundamental and field representations are just secondary.
In "Poincaré irrep", representation is mathematical jargon, it means representation of a group. But what do you mean by "field representation"?
is there a "conceptual shift" taking place towards an understanding that particles are more fundamental than fields?
Particles only exist in perturbation theory, so I don't see how that could happen.
 
Lapidus said:
In this Nima Arkani-Hamed paper on page 5 I found the sentence:

These constraints are an artifact of using fields as auxiliary objects to describe the interactions of the more fundamental particles.

In Schwartz's QFT book I also get away with the impression that the Poincaré irreps (i.e. particles) are more fundamental and field representations are just secondary.

But this view seems to be contrary with most other (older) QFT books and notes that I came across, where particles are just excitations of the fundamental quantum fields.

My question: is there are "conceptual shift" taking place towards an understanding that particles are more fundamental than fields?
I wouldn't say that Schwartz's QFT book promotes the idea that particles are more fundamental than fields. The opposite idea, that fields are more fundamental than particles, is still a mainstream. Yet the idea that particles could be more fundamental, pushed forward by Arkani-Hamed among others, is a legitimate idea worthwhile of further investigations.
 
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mitchell porter said:
Particles only exist in perturbation theory, so I don't see how that could happen.
If you start from fields, then it's true that particles only exist in perturbation theory. But it is not logically necessary to start from fields. See e.g. the old-fashioned S-matrix theory where people tried to derive S-matrix (for particles) directly from analyticity and certain symmetries, without using field theory. The recent work by Arkani-Hamed and others seems to be something similar.
 
Lapidus said:
In Schwartz's QFT book I also get away with the impression that the Poincaré irreps (i.e. particles) are more fundamental and field representations are just secondary.

Demystifier said:
I wouldn't say that Schwartz's QFT book promotes the idea that particles are more fundamental than fields.

I agree with @Demystifier.

@Lapidus: What makes you say that Poincaré irreps are only used to describe particles? For example, Weinberg did not title his books "Quantum Field Theory", he purposely titled them "The Quantum Field Theory of Fields", and Weinberg has an extensive discussion of Poincaré irreps.
 
Watch for the coming 3-volume book (in November 2018)

E. Stefanovich, Elementary particle physics. Vol. 1: Quantum mechanics, (De Gruyter Stud. Math. Phys. Vol. 45. Berlin: De Gruyter), 2018.
E. Stefanovich, Elementary particle physics. Vol. 2: Quantum electrodynamics, (De Gruyter Stud. Math. Phys. Vol. 46. Berlin: De Gruyter), 2018.
E. Stefanovich, Elementary particle physics. Vol. 3: Relativistic quantum dynamics, (De Gruyter Stud. Math. Phys. Vol. 47. Berlin: De Gruyter), 2018.

It promotes the idea that particles are the primary ingredients, but quantum fields are secondary.

Eugene.
 
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