What Came First the Magnet or the Field?

[bhobba]

Also QFT is deeply layered, and doesn't translate well into analogies like ripples in sheets.

And that is the real answer.

Its fields of quantum operators. Mathematical abstractions used to describe reality, whatever that is. Only by studying QFT can you appreciate it.

The book to delve into it is the following
https://www.amazon.com/dp/3319367560/?tag=pfamazon01-20

But it is just the start.

The real question is why are symmetries so important in physics. We simply do not know but it is without doubt the deepest discovery mankind has ever made, yet outside of physics hardly ever talked about.

Thanks
Bill

 

[Dadface]

I know you're trying to be helpful and I'm grateful for that but I can't see what you think is wrong with the first paragraph of the post. Let me summarise and break the paragraph down:

1. Ripples in the field are particles
2. In one type of field electrons are the particles.
3. Electrons have properties that can be measured
4. Electrons can be moved.
5. We are able to make observations on electrons without any knowledge of QFT

What's wrong with it?
Thank you

1. Particles are excitations of a field.
2. Electrons are excitations of the electron field.
3. These Excitations display themselves as physical phenomena that we can observe.
4. How can you move a single electron?
5. What observations do you mean?

Also QFT is deeply layered, and doesn't translate well into analogies like ripples in sheets.

Your summary points 1,2 and 3 are paraphrases of my summary points.
4 You know as well as I do some methods by which an electron can be moved. I'll just mention a couple of key words: ionisation,collision.
5 Observations include measurements eg of bare charge and mass. Some, of the methods used eg the use of mass spectrometry can be explained in terms of classical physics.
I think the analogies are used for the sake of brevity. You used an analogy in post 24.

 

[Ben Wilson]

Your summary points 1,2 and 3 are paraphrases of my summary points.
4 You know as well as I do some methods by which an electron can be moved. I'll just mention a couple of key words: ionisation,collision.
5 Observations include measurements eg of bare charge and mass. Some, of the methods used eg the use of mass spectrometry can be explained in terms of classical physics.
I think the analogies are used for the sake of brevity. You used an analogy in post 24.

Where is there an analogy in post 24?
Honestly, these questions aren't just to annoy. I have a problem with the wording you have used from a technical standpoint and i need to clarify what you mean with the terms that you are using. As others have said, the fields in qft are not a mental picture of what's going on at the particle scale, they are rigorously defined mathematical concepts that allow calculations to be made about observable phenomena; we as humans can then infer ripples in sheets as particles but this is not qft.
1.2.3. not paraphrased but made more precise, particles are not 'ripples' unless you had a precise mathematical description of what you mean by a ripple. When i say excitation, I know what i mean on a technical level, as I understand the concept of excitation from ordinary quantum mechanics.

4. I do not know as well as you do. I personally do not know how to move a single electron, QFT makes it possible (as far as my understanding goes) for there to be only one electron in the entire universe. How can i move this one electron by means of collision with another electron, when i only have one electron for instance. the point is that the particle picture is insufficient to describe 'moving an electron' if you intend to view the world through qft.

5. mass and charge are properties of quantum fields.

there's a subtle difference between brevity and poetry, brevity can still be technical but electrons are ripples is an analogy which is removed from the mathematical truth. you are trying to understand a quantum field in terms of other things. see http://www.damtp.cam.ac.uk/user/tong/qft/qft.pdf , if you don't understand this course then learn the prerequisites or accept that all analogies of an electron or a magnet or any quantum phenomena will be incomplete and insufficient. This is the nature of quantum mechanics.

 

[SEG]

@Dadface, it's a nice question about the foundations of physics. However, quantum fields are no building blocks, the combined fields are the structure of the universe. And phenomena like particles are no ripples but concentrations of quanta that emerge from the "primary" quantum fields (existend everywhere in the universe). That's why the electromagnetic field of an electron is a local quantum field. Without the electron, there is no electromagnetic electron field although the electron and the electromagnetic electron field emerge from the "underlying" primary quantum fields (vector field and scalar field).
Unfortunately, the biggest problem in theoretical physics is the existence of so many different concepts (hypotheses) and the lack of consensus. You easily can spoil your live by publishing a new concept. All the supporters of the other concepts will tell you you are wrong. ;-))

 

[Dadface]

Your summary points 1,2 and 3 are paraphrases of my summary points.
4 You know as well as I do some methods by which an electron can be moved. I'll just mention a couple of key words: ionisation,collision.
5 Observations include measurements eg of bare charge and mass. Some, of the methods used eg the use of mass spectrometry can be explained in terms of classical physics.
I think the analogies are used for the sake of brevity. You used an analogy in post 24.

Where is there an analogy in post 24?
Honestly, these questions aren't just to annoy. I have a problem with the wording you have used from a technical standpoint and i need to clarify what you mean with the terms that you are using. As others have said, the fields in qft are not a mental picture of what's going on at the particle scale, they are rigorously defined mathematical concepts that allow calculations to be made about observable phenomena; we as humans can then infer ripples in sheets as particles but this is not qft.
1.2.3. not paraphrased but made more precise, particles are not 'ripples' unless you had a precise mathematical description of what you mean by a ripple. When i say excitation, I know what i mean on a technical level, as I understand the concept of excitation from ordinary quantum mechanics.

4. I do not know as well as you do. I personally do not know how to move a single electron, QFT makes it possible (as far as my understanding goes) for there to be only one electron in the entire universe. How can i move this one electron by means of collision with another electron, when i only have one electron for instance. the point is that the particle picture is insufficient to describe 'moving an electron' if you intend to view the world through qft.

5. mass and charge are properties of quantum fields.

there's a subtle difference between brevity and poetry, brevity can still be technical but electrons are ripples is an analogy which is removed from the mathematical truth. you are trying to understand a quantum field in terms of other things. see http://www.damtp.cam.ac.uk/user/tong/qft/qft.pdf , if you don't understand this course then learn the prerequisites or accept that all analogies of an electron or a magnet or any quantum phenomena will be incomplete and insufficient. This is the nature of quantum mechanics.

Firstly let me reply to your comments up to and including points one two and three and beyond that to your closing paragraph. I think this discussion has deviated somewhat into semantics for example in post 24 and other places reference has been made to the word "excitation" whereas I referred to the word "ripples"... ripples is the word used by David Tong in the paper I referred to in the opening post.
David Tong has quite an impressive background in the world of theoretical physics. Amongst other places he has had a research career at TIFR Mumbai, Stamford, MIT and Cambridge. He has a bunch of prizes, fellowships and awards and at present is a professor at university of Cambridge and a fellow of Trinity College. He works on QFT and he described particles in terms of ripples. Because of his experience in the subject I consider it reasonable for me to adopt his terminology. But you prefer to describe particles in terms of excitation's That's fair It's a word I can use .In fact I probably will use it.

4. I think you've pointed out another example of so called quantum weirdness. If QFT really makes it possible for there to be only one electron in the whole universe then I think that's a failing of QFT. I base that on a mega powerful theory, the theory of general knowledge and common sense. How can the electrons involved in the biochemical process of digesting my fish and chips and the electrons smashing into the targets of X ray tubes and so on and so on all be a single electron? By the way I don't want to discuss that here.

5. I agree with point 5 but to clarify your statement and be more precise I would add that mass and charge are properties of excitations of fields in other words properties of particles. And that's one of the points i was trying to make.

I think we've gone about as far as we can go with this discussion and I thank you very much for all your input. It has made made me think more deeply about the matter and as a result my understanding has improved.

 

[weirdoguy]

David Tong has quite an impressive background in the world of theoretical physics.

Oh please. Still pop-science is pop-science no matter who is doing it.

 

[Ben Wilson]

Oh please. Still pop-science is pop-science no matter who is doing it.

think this discussion has deviated somewhat into semantics for example in post 24 and other places reference has been made to the word "excitation" whereas I referred to the word "ripples"... ripples is the word used by David Tong in the paper I referred to in the opening post.

i linked you to david tongs qft course, he says ripple for a quick mental picture for the reader in the intro, this is an analogy. In the course he says excitation, because there's a consensus amongst physicists about what this means in a mathematical sense (see p 29). It doesn't matter what word you use, you are allowed to say ripple, provided the word ripple carries a precise physical meaning e.g. a creation operator applied to a Fock space. For the final time, it has nothing to do with semantics or picking on words you are using.

 

[Dadface]

Oh please. Still pop-science is pop-science no matter who is doing it.

I would appreciate it if you don't comment on small sections of posts out of context but try to look at the whole thing. Is your comment relevant when you look at post fourteen? is your comment constructive in any way?

 

[PeterDonis]

try to look at the whole thing

We already have, and the correct response has been given to you repeatedly: if we are talking about quantum field theory, then everything is made of quantum fields. "Particles" are made of quantum fields. "Electric and magnetic fields" are made of quantum fields. You and I are made of quantum fields. That's all there is to it.

This thread has already beaten the above point to death. Thread closed.