The discussion centers on the nature of force particles in high-energy and particle physics, specifically within the framework of quantum field theory (QFT). Participants clarify that there are four fundamental forces, each associated with a force particle: electromagnetism (photon), strong nuclear (gluon), weak nuclear (W and Z bosons), and gravity (hypothetical graviton). The conversation emphasizes that while these particles are often referred to as such, they also exhibit wave-like properties, leading to confusion about their classification. The distinction between particles and wave functions is critical, as the latter describes probabilities rather than physical entities.
PREREQUISITESStudents and researchers in physics, particularly those focusing on high-energy physics, quantum mechanics, and the Standard Model, will benefit from this discussion. It provides insights into the complexities of particle classification and the underlying theories governing their behavior.
atyy said:Particle is just a bad, but standard name for a quantized excitation of a field. See ZapperZ's posts #4 & 5 for other "force carriers" in condensed matter physics.
Nano-Passion said:I would have rather heard the term "quantized excitation" than "particle" a loong time ago. Which is why I was frustrated with the thread earlier, there were too many inconsistencies with respect to terms and semantics.
You won't hear people use the expression "wave/particle duality" much in the context of modern quantum theory. It's more a term that was used in the early days (first half of the 20th century) when people were still struggling with the question of whether the fundamental constituents of nature were better described as particles or as waves.Nano-Passion said:I would have rather heard the term "quantized excitation" than "particle" a loong time ago. Which is why I was frustrated with the thread earlier, there were too many inconsistencies with respect to terms and semantics.
belliott4488 said:You won't hear people use the expression "wave/particle duality" much in the context of modern quantum theory. It's more a term that was used in the early days (first half of the 20th century) when people were still struggling with the question of whether the fundamental constituents of nature were better described as particles or as waves.
I prefer to say that both terms are classical in nature, and that neither one correctly (or completely) captures the behavior of quantum "entities". Rather, I like to think of everything as a quantum field. Such a thing can be observed, and in the process it will exhibit particle-like properties. To predict its behavior, however, you must propagate a field, which is where it exhibits wave-like behavior.
As for why the interactions are mediated by fields that can exhibit particle-like behavior - they just do. The oldest example is the photon, whose existence Einstein first postulated in 1905 in his photoelectric effect paper - the electromagnetic field was behaving like a particle. Nowadays W and Z particles leave traces in particle detectors, i.e. they behave like particles. But they also mediate the electroweak interaction - they just do.
I suppose you could say that these fields behave like particles when they are observed and like waves when they propagate ... but I'd rather just say that they behave like quantum fields and leave it at that.
cbetanco said:In post 24, juanrga already points out that fields are not more fundamental than particles. So while it is useful to think of particles as excitation of fields, and indeed the one particle states of a particle at a position x in QM can be written as |x>=\psi (x) |0>, where |0> is the vacuum state and \psi (x) is the field at point x. That is, when a field operates on the vacuum, it creates a particle at point x.
Perhaps your confusion is that you are thinking of a particle in the traditional sense, that is a infinitely small billard ball with a definite position. In field theory, particles are really irreducible representations of the Poincare group and some gauge groups (U(1), SU(2), etc.). I like to think of them as little chunks of the symmetry of our universe, but maybe this is not entirely correct. That is, to me the universe has some symmetry, and particles are the simplest form of how the symmetry manifests itself.