Particles vs. Virtual Particles vs. Fields

In summary, the photon is the force carrying particle for the electromagnetic force, similar to how W and Z bosons carry the weak force. This can be confusing when thinking about the interaction between an electromagnet and a piece of iron, as it may seem like photons are constantly shooting out of the electromagnet. However, the reality is that the electromagnet creates an electromagnetic field which interacts with the iron to create an attractive force. This field is described mathematically by virtual photons, which are not "real" particles but rather a way to model interactions. This concept of virtual particles only seems to be discussed in relation to photons and it is unknown if other force carrying particles like W and Z bosons also have virtual counterparts. Additionally, it
  • #1
industry7
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It's easy to find references which explain that the photon is the force carrying particle for the electromagnetic force (ie https://en.wikipedia.org/wiki/Force_carrier). Similarly there are force carrying particles for other forces, like W and Z bosons carry the weak force.

This has always been confusing to me though. For example, I remember learning in school that an electromagnet, supplied with power, produces an electromagnetic field. That field is what attracts a piece of iron. But now I know that the iron is actually being attracted by the force carrying particles, photons. So photons are constantly shooting out of the electromagnet and when they hit the piece of iron, then the iron experiences an attractive force.

So then why don't I see photons shooting out of electromagnets?

Also, if photons are the force carrying particle, does that mean that there is no actual field? It's just the photons? I've read that force carrying particles are "not real" in the sense that they are actually excitations of their respective fields. I'm not entirely sure what to make of that. It seems to imply that when a photon is shooting through the vacuum of space (say, on its way from a distant star to a telescope on Earth), that there must exist an electromagnetic field which permeates all of space for the photon to travel through. Since obviously a field has to exist to being with in order for there to be an excitation of that field. But then how is that any different from the old and debunked aether theory? (see https://en.wikipedia.org/wiki/Luminiferous_aether for reference)

Speaking of fields, I thought it was possible to have a magnetic field without any accompanying electric field, and vice versa. This implies photons with only one component, electric, or magnetic. Do the photons coming out of my flashlight have both components? Do they have to?

Finally, virtual particles. I've also read in some places that force carrying particles are actually virtual particles. To my understanding, this means that you can model interactions with forces as though quantized packets of energy were being exchanged between the objects in question. So this would mean that a magnet attached to my fridge is not transferring real photons to the surface of the fridge (real in the sense of being like photons you'd see from a flashlight), but rather only virtual particles are being exchanged.

But then I never see anything talking about virtual vs real for other types of particles, only photons. Are there both real and virtual W bosons? Are there both real and virtual Higgs bosons? I assume no, since I've never read about them, but then plenty of stuff exists which I've never heard of...

This has all been rather rambly, so I'll wrap it up with one final question. If photons are the force carrying particle for the electromagnetic force, then why can't I place a magnet between myself and a light-source, and see a visual effect produced from the interaction between the photons coming from my light source and the magnetic field from my magnet?
 
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  • #2
industry7 said:
That field is what attracts a piece of iron. But now I know that the iron is actually being attracted by the force carrying particles, photons. So photons are constantly shooting out of the electromagnet and when they hit the piece of iron, then the iron experiences an attractive force.

That's not what happening. The electromagnet is creating an electromagnetic field just like you always thought, and the interaction between that field and the iron is creating a force drawing the iron towards the magnet just like you always thought. The virtual photons appear as part of the mathematical description of how the iron interacts with the field.
 

Related to Particles vs. Virtual Particles vs. Fields

1. What are particles?

Particles are small, indivisible units of matter that make up the physical world. They can be thought of as the building blocks of everything around us, including atoms, molecules, and larger structures.

2. What are virtual particles?

Virtual particles are theoretical particles that are not directly observable, but are believed to exist based on their effects on other particles. They are constantly popping in and out of existence and are responsible for mediating certain fundamental forces, such as the electromagnetic force.

3. What is the difference between particles and virtual particles?

The main difference between particles and virtual particles is that particles have a real, physical existence whereas virtual particles are only theoretical and do not exist in the same way as particles do. Virtual particles also have a shorter lifespan and can only exist in certain conditions.

4. What are fields?

Fields are regions of space that have a measurable value at every point. They can be thought of as a property of space itself and can influence the behavior of particles and virtual particles. Examples of fields include the gravitational field, electric field, and magnetic field.

5. How are particles, virtual particles, and fields related?

Particles and virtual particles are both affected by fields, as fields can interact with and influence their behavior. The concept of fields is used to explain the interactions between particles and virtual particles, and how they can affect each other even when not in direct contact.

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