Quantum field theory questions?

I think that there is a vacuum ##|0\rangle## for the electrons, another for photons and so on. There is creation operator ##a^\dagger## for each field. The vacuum has a null occupation number(##a^\dagger a |0\rangle = zero##. You can call quantum the result of a creation operator on a vacuum (as the result has a number of 1)

 

You know that in an hydrogen atom an electron may be on his ground state (lower energy) he may be excited when a photon has been annihilated by the electron.
When we speak of fields we say that a field is in is ground state ##|0 \rangle## when its energy is minimum. its particle number is null. This field can interact with another field so that it is excited. it is no more on the ground state but in a state with a particle occupation number equal
to one. That is why we say the electron is an excitation of the electronic field
the word quanta is not important.

 

So electrons in atoms can be modelled as excitations of the electron field.. but why do we still discuss about whether electrons are particle or wave in the atoms.. why not just mention them as field excitations?

But then, is it possible this model of electron as field excitations can be replaced with other models.. meaning qft is just a temporary or effective field theory?

 

I bought the book you suggested above and reading it since yesterday. But it says qft didn't solve the mystery of the double slit too. Quoting in the book:

"Field collapse: Field collapse is not an easy concept to accept- perhaps more difficult than the concept of a field. Here I have been working hard, trying to convince you that fields are a real property of space - indeed, the only reality - and now I am asking you to believe that this field quantum, spread out as it may be, suddenly disappears into a tiny absorbing atom. Yet it is the process that can be visualized without inconsistency. In fact, if a photon is an entity that lives and dies as a unit, field collapse must occur. A quantum cannot split and put half its energy in one place and half in another, or live here and die there. That would violate the basic quantum principle. While QFT does not provide an explanation for when or why collapse occurs, somne day we may have a theory that does. In any case, field collapse is necessary and has been demonstrated experimentally."

Bill, Is this why the double slit experimental are not explained using QFT.. because field collapse is just as inexplanable as particles passing both slits? Also I think most physicists don't attribute any physical existence of the quantum fields.. and field collapse if real needs instantaneously faster than light signaling.. this is almost like saying the wave function was real.. only this time the quantum fields are real but fields collapse superluminally. What is your thoughts of this?

 

Bill. Have you actually read the book you recommended days ago (the "Fields color theory escaped Einstein"? I finished reading it and it's a very unusual book with a different interpretation of QFT and even special relativity. For example. There is a passage inside that says:

"While I hope you can accept, as did FitzGerald and Lorentz, that length contraction happens because the field equations require it, it would be nice to have some intuitive insight into the phenomenon. We must recognize that even if the molecular configuration of an object appears to be static, the component fields are always interacting with each other. The EM field interacts with the matter fields and vice versa, the strong field interacts with with the nucleon fields, etc. These interactions are what holds the object together. Now if the object is moving very fast, this communication among fields will become more difficult because the fields, on the average, will have to interact through greater distances. Thus the object in motion must somehow adjust itself so that the same interaction among fields can occur. How can it do this? The only way is by reducing the distance the component fields must travel. Since the spacing between atoms and molecules, and hence the dimensions of an object, are determined by the nature and configuration of the force fields that bind them together, the dimensions of an object must therefore be affected by motion"

He also explains why time dilation occurs because the fields need finite time to travel in between atoms. And the reason c can't be exceeded is because the fields need finite speed. And mass increase because of more inertia the fields have to resist. Ok. Why don't I see these explanations given by the average physicists? And how many subscribe to this view?

About General Relativity. It says something like "What Schwinger is saying is that four dimensional geometry does not exist in the real world - it is "impossible", but matheticians "who think algebraically" are free to construct equations that would describe it if is did exist. By stretching our minds, some of us can even form a vague mental image of what four-dimensional curvature would be like if it did not exist. Nevertheless, saying that the gravitational field equations are equivalent to curvature is not the same as saying there is curvature. In QFT, the gravitational field is just another force fields, like the EM, strong and weak fields, albeit with a greater complexity that is reflected in its higher spin value of 2."

Read the rest in the book.

For others besides Bill. Can you share or comment what could possible be wrong with it?

 

QFT is about operators acting on the state vectors and these are not supposed to be physical.. but why did the author kept emphasizing the field is physical and in fact literally pass thru both slits and then the fields vanish when one part gets "detected" by the detector atom? Who are other physicists who hold this view?

 

I read in sci am that "A classical field is like a weather map that shows the temperature in various cities. The quantum version like a weather map that does not show you "40 degree," but "sqrt ()". To obtain an actual temperature value, you would need to go through an extra step of applying the operator to another mathematical entity, known as a state vector, which represents the configuration of the system in question"

How could these operator fields be physical like in qm position or momentum? And our instrument just detects particles.. we can't detect the raw field.. in the same manner we can't detect wave function because these are just mathematical devices to produce detections. Do you attribute the quantum fields as more real than wave function? But function fields are composed of configuration of wave functions too, and they collapse similarly to QM wave function so how can the quantum fields wave function be more real?

Also what is the theoretical reason why we can't apply QFT to a piece of wood such that the atoms can be annihilated or be created making the wood indeterminate.. I read something like QFT can be applied to free fields (?) only and not to bound states like atoms. Why?

 

But how do you detect electron fields? We detect electron particle instead of the electron field.

But QFT deals with annihilation and creation operators.. if you apply this to wood.. won't this just destroy it since you are annihilating the wood atoms making it vanish?

 

The problem is that there is no apple tree fields interacting with EM field. If so we could easily get fruits from a laser.

 

In QM, time is a parameter in that all system have similar time. But Einstein says time varies in different locations, so in QFT, we have time as coordinate.. but a fixed coordinate. .

General Relativity teaches us that spacetime is curved in the presence of matter.. so QFT can be further improved to have fields that can interact with the geometry. I'd like to know if general relativitisic QFT would be simply about planck scale physics (or quantum gravity) or it would also predict or model other above planck scale effects like information dynamics (for example from the holographic principle) akin to how QFT can give us interactions and particles that can annihilate or create (larger than planck scale) versus that of plain QM?