What Came First the Magnet or the Field?

[Dadface]

Below I paraphrase David Tong from:

David Tong -- What is Quantum Field Theory? You can find this by googling.

1. "According to our best laws of physics the fundamental building blocks of nature are fields."

2." Every particle in the universe ... is a tiny ripple of the underlying field"

According to basic school physics if we move the magnet we move the field. But it seems that according to QFT it's sort of the other way round and to move the magnet we must move the field. The only way I can think of moving the field is by moving something else, for example moving a second magnet. It's a bit chicken and egg.

So is the field more fundamental than the particles of the magnet? Or, perhaps, should particles and fields share equal dominance as being considered as fundamental?

 

[Vanadium 50]

. But it seems that according to QFT it's sort of the other way round and to move the magnet we must move the field.

How on Earth did you get that?

 

[Dadface]

How on Earth did you get that?

I got it from the article I referred to where it was stated that fields (not particles) are the "fundamental building blocks of nature".. One way I see of interpreting that is to assume that to make changes to the particles you need to make changes to the fields. But traditionally it's the other way round which is to make changes to the fields you need to make changes to the particles eg move the magnet. I imagine particles and fields as being interlinked as a particle/field construct and I can't see why one aspect of that construct, namely the field aspect should be considered as being more fundamental than the other aspect.

Sorry I tried to include a link but it didn't work.

 

[atyy]

In QFT, the magnet is also made from fields.

 

[Dadface]

In QFT, the magnet is also made from fields.

And particles.

 

[atyy]

And particles.

Particles are excitations of fields.

 

[Ben Wilson]

And particles.

the 'magnet' and the 'magnetic field' are different things, so they are described with different fields.

 

[Dadface]

Particles are excitations of fields.

Changes in fields can cause changes in particles.
Changes in particles can cause changes in fields.
What came first?

 

[Dadface]

the 'magnet' and the 'magnetic field' are different things, so they are described with different fields.

Not sure about the point being made. What of the two different fields describes the magnetic field?

 

[Ben Wilson]

Not sure about the point being made. What of the two different fields describes the magnetic field?

two fields do not describe the magnetic field. the magnetic field is ONE field, the magnetic field. however, with your taking about a magnet and a magnetic field: particles are electron* and photon, fields are electron and electromagnetic respectively.

*for example

 

[Ben Wilson]

Changes in fields can cause changes in particles.
Changes in particles can cause changes in fields.
What came first?

no that's a sloppy description of what's going on, particles are excitations of a quantum field.

 

[Dadface]

the 'magnet' and the 'magnetic field' are different things, so they are described with different fields.

two fields do not describe the magnetic field. the magnetic field is ONE field, the magnetic field. however, with your taking about a magnet and a magnetic field: particles are electron* and photon, fields are electron and electromagnetic respectively.

*for example

It was you who suggested that the magnetic field is described by a field (post 7). That was unclear but now you've cleared it up. But I still don't see the relevance of your comments.

 

[Ben Wilson]

It was you who suggested that the magnetic field is described by a field (post 7). That was unclear but now you've cleared it up. But I still don't see the relevance of your comments.

when you move the magnet what particles are you moving?

 

[Dadface]

no that's a sloppy description of what's going on, particles are excitations of a quantum field.

I'm not disagreeing that particles can be described as excitations of the field. I quoted David Tongs description of a particle in post one and I did not dispute atyy's definition, which is worded in the same way as yours in post six. So to make it clear I am not disputing anything about QFT. In fact I don't know enough about it yet to be able to do that.
What I am questioning is the assumption that fields are more fundamental than particles. And I am doing that by reference to changes. So why is my reference to changes in post 8 an example of sloppy thinking? Please take another look at post one.

 

[Ben Wilson]

I'm not disagreeing that particles can be described as excitations of the field. I quoted David Tongs description of a particle in post one and I did not dispute atyy's definition, which is worded in the same way as yours in post six. So to make it clear I am not disputing anything about QFT. In fact I don't know enough about it yet to be able to do that.
What I am questioning is the assumption that fields are more fundamental than particles. And I am doing that by reference to changes. So why is my reference to changes in post 8 an example of sloppy thinking? Please take another look at post one.

I do not mean sloppy thinking, just a sloppy description in an academic sense, i.e. not very pedantic or precise. I'm saying that when these things are more clear and defined, the chicken and egg problem goes away in my view.

 

[Dadface]

when you move the magnet what particles are you moving?

To a large extent that depends on the system within which the magnet is moved.

 

[Ben Wilson]

To a lsrge extent that depends on the system within which the magnet is moved.

I'm asking you what particles the 'magnet', e.g. an iron bar magnet, is made of? its electrons, which are not excitations of the magnetic field, but they do 'cause' the magnetic field in some physical sense.

 

[Dadface]

I'm asking you what partices the 'magnet', e.g. a simple bar magnet, is made of.

I think we both know the answer to that but what's the point of the question?

 

[Dadface]

Will be back here later on.

 

[tech99]

Below I paraphrase David Tong from:

David Tong -- What is Quantum Field Theory? You can find this by googling.

1. "According to our best laws of physics the fundamental building blocks of nature are fields."

2." Every particle in the universe ... is a tiny ripple of the underlying field"

According to basic school physics if we move the magnet we move the field. But it seems that according to QFT it's sort of the other way round and to move the magnet we must move the field. The only way I can think of moving the field is by moving something else, for example moving a second magnet. It's a bit chicken and egg.

So is the field more fundamental than the particles of the magnet? Or, perhaps, should particles and fields share equal dominance as being considered as fundamental?

You can move the magnet by means other than the magnetic field maybe? A magnet contains charges, which although in motion, might perhaps be moved by an electric field?

 

[Dadface]

You can move the magnet by means other than the magnetic field maybe? A magnet contains charges, which although in motion, might perhaps be moved by an electric field?

Yes there are different ways of moving the magnet.

 

[Ben Wilson]

Yes there are different ways of moving the magnet.

what particles are your magnets made of? If you pick somethin then i can explain the qft behind it and answer your question

 

[Dadface]

what particles are your magnets made of? If you pick somethin then i can explain the qft behind it and answer your question

Lets go with up and down quarks and electrons.

 

[Ben Wilson]

Lets go with up and down quarks and electrons.

Just focusing on the one important particle for magnetic fields out of those, electrons are excitations of an electric field. Interacting electrons exchange photons between each other and even themselves because the dynamics of the electron field is coupled with the electromagnetic field in a QED. Photons are excitations of the electromagnetic field. If you move the 'magnet', you will move the electrons. The electrons will interact through the electromagnetic interaction in the new place, giving excitations of the em field.

magnets rarely use nuclei as their magnetic moment is thousands of times smaller than electrons, however MRI scanners utilize the magnetic properties of nuclei.

 

[Ben Wilson]

According to basic school physics if we move the magnet we move the field. But it seems that according to QFT it's sort of the other way round and to move the magnet we must move the field. The only way I can think of moving the field is by moving something else, for example moving a second magnet. It's a bit chicken and egg.

you say to move the magnet we must move the field. Now you have to distinguish between em(magnetic) field or electron field.

 

[PeterDonis]

According to basic school physics if we move the magnet we move the field. But it seems that according to QFT it's sort of the other way round and to move the magnet we must move the field.

No, according to QFT moving the magnet is moving the field. Everything is fields--you are fields, so when you move the magnet it is fields moving fields.

You need to stop and seriously think about what "fields are the fundamental building blocks of everything" actually means.

 

[Demystifier]

Lets go with up and down quarks and electrons.

What you fail to understand is that electric and magnetic field are not the only fields out there. There is also quark field, electron field, etc. The world is not made of particles and fields. Instead, according to QFT, the world is made of fields. It doesn't mean that particles do not exist. They do, but they are made of fields too.

 

[Dadface]

Thank you everyone who commented but before I reply to specific comments may I please ask you to look again at my original post..

 

[weirdoguy]

may I please ask you to look again at my original post..

I think that you should look at it again. It seems that you completely don't uderstand what "particles are excitations of fileds" imply.

 

[Dadface]

What you fail to understand is that electric and magnetic field are not the only fields out there. There is also quark field, electron field, etc. The world is not made of particles and fields. Instead, according to QFT, the world is made of fields. It doesn't mean that particles do not exist. They do, but they are made of fields too.

I know from my comments it may seem that I don't know about other fields but I do. At odd times during the last few weeks I've been reading up on the subject. In the article I referred to David Tong stated:

"The most familiar example of fields are the electric and magnetic field."

I used the example of a magnet because it's familiar.