Quantum field theory and wave particle duality

In summary, David Tong explains quantum fields in a concise and easy-to-understand way. He shows that fields for particles and fields for forces are related, and that there is no wave-particle duality in modern quantum theory.
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LifelongLearner125
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TL;DR Summary
Quantum field theory (QFT) states that every thing is a field, particles are fields and forces are fields. The early quantum theory talks a lot about electrons behaving like a particle and a wave. Is it the same phenomenon as explained by QFT that particles have a corresponding field associated with them which can 'wave'?
I recently watched this lecture "Quantum Fields: The Real Building Blocks of the Universe" by David Tong where the professor provides a succinct explanation of QFT in about 6 minutes around the midway mark.


The main point being that there are fields for particles and fields for forces and the particles get their properties by the interaction of the particle fields with the force fields. Like Charge of an electron is the outcome of the electron field interacting with the field associated with electromagnetic force.
is this notion of particles having a field same or corresponds to the wave particle duality of early quantum physics that is often described using the double slit experiment?
 
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LifelongLearner125 said:
there are fields for particles and fields for forces
And yet the "fields for forces" have particles too--the photon is the particle of the electromagnetic force field.

I see what he's basically trying to get at--he's referring to the distinction between boson and fermion fields, where the former are "forces" and the latter are what he calls "particles"--but I don't think it's anywhere near as simple as he seems to be trying to make it.

LifelongLearner125 said:
is this notion of particles having a field same or corresponds to the wave particle duality of early quantum physics that is often described using the double slit experiment?
Not really. The early QM "wave particle duality" was just a way of describing how surprised physicists were at that time that everything could be made to behave like either a particle or a wave, depending on what experiment you did. Physicists before that had thought that things like light were waves and things like electrons were particles. Then they did experiments that showed light behaving like particles and other experiments that showed electrons behaving like waves, and everyone started saying "wave particle duality" as if that somehow explained what was going on instead of just describing their confusion.

In quantum field theory, "wave" and "particle" are just shorthand ways of describing certain kinds of quantum field states. The same experimental results that confused everybody before are still there, but now they have an actual explanation: that the underlying entities are neither waves nor particles, but quantum fields, and yes, you can do certain experiments that make quantum fields behave like particles, and other experiments that make them behave like waves. And you can also find quantum field states that can't be easily described as either particles or waves.
 
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I think that "wave-particle duality" strictly and exclusively belongs to the "old quantum theory". None of the physicists developing this "theory" has been satisfied with it to begin with. Particularly Einstein was very critical about his own work about "light quanta".

The resolution of all the quibbles of "old quantum theory" is "modern quantum theory", developed in three versions in 1925/26: (a) matrix mechanics, heuristically stated by Heisenberg, then worked out by Born and Jordan (including quantization of the electromagnetic field by the way, (b) wave mechanics by Schrödinger (including the proof that it's equivalent to matrix mechanics), (c) transformation theory by Dirac (the representation free formulation with operators and bras and kets, including also quantization of the electromagnetic field).

According to modern quantum theory there is no self-contradictory wave-particle dualism anymore. That relativsitic QT is today formulated exclusively as QFT is due to the fact that when having scattering processes at "relativistic energies" there are no conserved particle numbers of any kind. Only the various charges of the Standard model (electric charge, baryon number, etc.) are conserved but you create and annihilate all kinds of particles in such processes. That's why a QFT formulation is most convenient, because QFTs particularly describe such situations where particles can be annihilated and created.
 
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FAQ: Quantum field theory and wave particle duality

What is quantum field theory?

Quantum field theory is a theoretical framework that combines the principles of quantum mechanics and special relativity to describe the behavior of particles at the subatomic level. It is based on the concept of fields, which are mathematical representations of physical quantities that permeate all of space and time.

How does quantum field theory explain wave-particle duality?

According to quantum field theory, particles can exhibit both wave-like and particle-like behavior. This is because particles are described as excitations in their corresponding quantum fields, and these excitations can behave like waves. This duality is a fundamental aspect of quantum mechanics and is necessary to explain many phenomena at the subatomic level.

Can you provide an example of wave-particle duality in action?

One example of wave-particle duality is the double-slit experiment. In this experiment, a beam of particles, such as electrons, is directed towards a barrier with two narrow slits. The particles behave like waves as they pass through the slits and interfere with each other, creating a pattern of light and dark bands on a screen behind the barrier. This phenomenon demonstrates the dual nature of particles as both waves and particles.

How does quantum field theory relate to the standard model of particle physics?

The standard model of particle physics is a theory that describes the fundamental particles and forces of nature. It is based on the principles of quantum field theory and is currently the most accurate and comprehensive model we have for understanding the subatomic world. The standard model includes the three fundamental forces of nature (electromagnetism, strong nuclear force, and weak nuclear force) and the particles that mediate these forces.

What are the practical applications of quantum field theory?

Quantum field theory has many practical applications in fields such as particle physics, condensed matter physics, and cosmology. It is used to make predictions and calculations about the behavior of particles and their interactions, which can then be tested and verified through experiments. Quantum field theory has also led to the development of technologies such as transistors, lasers, and magnetic resonance imaging (MRI).

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