I get that it’s values. It’s like, you assign a value to every point in space. But what “is” the electron field? It’s… what? I mean like a Kantian “field an sich”. Is the electron field the amount of electron-ness at a given point in space? What does that even mean beyond a calculation?
Are fields “real entities” with an objective physical reality? Or are they just mathematical abstractions that we use for calculation? Can you talk about fields without math? Does that even make sense? Like, I can talk about electrons without math. I can say they’re point particles that carry charge. But can you talk about the electron field outside of math? Or the EM field? Does it genuinely exist outside of an Electrodynamics calculation?
In: 56
As a simple ELI5
A field is just an area where something can be affected by a force
There are other things to consider, like different parts of the areas having different strengths, but being in an area of higher strength just means there’ll be a bigger force in that area
I think probably the simplest description is “a zone of influence (or zone where some influence can be observed) surrounding a phenomenon.” The field is not solely the source itself, it is the region where whatever the source does has impact without direct contact being required.
It is a pretty vague term for a pretty vague thing. The “value” that gets assigned is just a way to measure the magnitude of the effect produced by the phenomenon at a specific location.
Fields usually, but are not required to, involve a distance parameter as one of the variables to the mathematical function used to define the behavior of the field.
>Can you talk about fields without math? Does that even make sense?
No, not really, it’s entirely a mathematical concept. Physics doesn’t quite try and explain what reality really is, more accurately it explains how reality behaves, using mathematical models.
If Newton treats forces as vectors, there is no such thing as a vector in a real world, it’s merely a mathematical concept. Same thing with fields.
Think of it like this:
There is a river. Lets say that water is made of little balls. Each ball has some velocity (a speed and a direction to it) and this velocity depends on where the ball is. At the bank the flow is slower and faster towards the center for example.
So even though the velocity of the flow in the river is not independent from the water that is flowing, mathematically we can separate them and say that the flow of water is a function of location. I give you a location and the function tells me the velocity at that location. This is a vector field. Physically you can’t separate the electric field from the charges that creat it but mathematically you can work with the field as its own separate thing. Its the model.
The electric field is defined as the force that would act on a unit positive charge at a given point. The physics is that charges interact through the EM filed and the mathematical model is that we consider the E vector field and this vector field determines motion for charges. Much like how I can say that there is a velocity vector field and I pour water into it and the water flows accordingly. Of course without the water that field doesn’t physically exist, its a mathematical abstraction.
So ok how do charges interact then, like what is the mechanism. Well, well well, good question. Currently our best theory is quantum field theory which consider quantum fields, where particles are excitations in corresponding field and interactions happen in fields as well. These fields (by QFT) are what physical reality is. However it is worth pointing out that just because a model works well doesn’t mean its what reality is. For example before we could see an atom, the atom model existed, but are these little quantized balls? Reality we didn’t know. What models suggest and what reality “is” are correlated in complicated and nontrivial ways. After a certain point it becomes really difficult to say what something “is”. And its arguably more of a philosophical question.
What physics can do is to model reality more and more accurately. What it can’t do is to guarantee that these models coverage to actually reality. It’s really hard to decide whether your model is a 1:1 representation of reality or an equivalent way of treating it and after a certain point it could be undecideable.
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