Can particles interact without a mass?

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Discussion Overview

The discussion revolves around the possibility of particle interactions in the absence of mass, particularly in the context of the Higgs boson and its role in the early universe. Participants explore theoretical implications, definitions of mass, and the nature of interactions among massless particles.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question whether the Higgs boson could have been the primordial atom that initiated the universe, given that the Higgs field was zero and could not provide mass.
  • It is proposed that mass is not a requirement for particle interactions, as interactions can occur through charge and force carriers.
  • Participants discuss the distinction between rest mass and total mass, with some asserting that photons have zero mass while others argue that all particles possess mass in some form.
  • The Higgs mechanism is mentioned as a process that allows particles to acquire mass through their interaction with the Higgs field.
  • There is contention regarding whether force carriers can have mass, with some asserting that they cannot while others note exceptions in specific theories.
  • Discussions touch on the implications of mass terms in quantum electrodynamics (QED) and electroweak theory, with varying opinions on their allowance and relevance.
  • Participants also mention gluons and their role in mass dynamics, noting that they do not have rest mass but contribute to baryon mass through interactions.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of mass in particle physics, particularly regarding the Higgs field and its role in interactions. There is no consensus on the nature of mass or the specifics of particle interactions without mass.

Contextual Notes

Limitations include varying definitions of mass, the dependence on theoretical frameworks, and unresolved questions about the nature of interactions in different contexts, such as QED and electroweak theory.

  • #31
ohwilleke said:
It follows from the fact that there is a finite amount of mass-energy in the Universe
Only in the observable universe. The universe as a whole is spatially infinite.

ohwilleke said:
conservation of mass-energy
Which is a local concept in GR, not a global one. In a non-stationary spacetime, such as the spacetime that describes our universe as a whole, there is no conserved global energy.

ohwilleke said:
which is very basic and uncontroversial premises of the Big Bang theory of cosmology
I think you are either misunderstanding or misstating the theory.
 
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  • #33
ohwilleke said:
A good background discussion of asymptotic safety which I oversimplify in my comment can be found in this published open source paper (Eichhorn 2019) (particularly Part 5). See also here and here. Also here (discussing distinction between classical GR singularity Big Bang at infinite temperature and limitations on that in a quantum gravity scenario).
All of these are speculative quantum gravity models, not mainstream cosmology. Discussion of them belongs in the Beyond the Standard Model forum, not here.

Also, it is rather inconsistent of you to first emphasize that all physics above energy scales we can currently probe is speculative and should be taken with a grain of salt, and then to inundate us with such speculations.
 
  • #34
Why should energy not be conserved globally?
 
  • #35
Prishon said:
Why should energy not be conserved globally?
In GR, it's more that there isn't even a well-defined global concept of "energy" except in a special class of spacetimes (the stationary spacetimes).
 
  • #36
I don't follow... Can you give a link? I am very interested.
 

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