# Thread: What is a 'field'

1. How is it that at 1cm from a magnet, charged particles and metallic conductors are influced to behave a certain way, yet it behaves another way at a mid point say 3cm away from the magnet? What is it that causes this? Is it the photons that are giving the instructions for the particles in the metal to behave?

I have always had difficultly understanding exactly what a field is. Is a magnetic field always constant in any medium it occupies? Gas/solid/liquid/plasma/vacuum? Is whatever the field is being propogated by affected by the medium its source is in?

2.

3. There no " field " the space is empty , but the partical move forward and backward in time , so it can feel the many option whats ahead

4. Is it just me, or is there an unusual amount of nonsense being posted lately?

5. Originally Posted by Quantime
I have always had difficultly understanding exactly what a field is. Is a magnetic field always constant in any medium it occupies? Gas/solid/liquid/plasma/vacuum? Is whatever the field is being propogated by affected by the medium its source is in?
From what i know, magnetic field is created by rotating charge in all substance. What it need is just that substance to have a net rotation to create a net magnetic field that could dampen or amplifies existing magnetic field. It is Lenz law.In classical physic the field is less dense at longer range, but don't know how this is interpreted in "magnetic field as particle" point of view.

6. IMO, a field is a spacetime 'condition' with certain inherent qualities.

In physics, a field is a physical quantity that has a value for each point in spacetime.[1] A field can be classified as a scalar field, a vector field, a spinor field, or a tensor field according to whether the value of the field at each point is a scalar, a vector, a spinor (e.g., a Dirac electron) or, more generally, a tensor, respectively. For example, the Newtonian gravitational field is a vector field: specifying its value at a point in spacetime requires three numbers, the components of the gravitational field vector at that point. Moreover, within each category (scalar, vector, tensor), a field can be either a classical field or a quantum field, depending on whether it is characterized by numbers or quantum operators respectively.

A field may be thought of as extending throughout the whole of space. In practice, the strength of every known field has been found to diminish with distance to the point of being undetectable. For instance, in Newton's theory of gravity, the gravitational field strength is inversely proportional to the square of the distance from the gravitating object. Therefore the Earth's gravitational field quickly becomes undetectable (on cosmic scales).

Defining the field as "numbers in space" shouldn't detract from the idea that it has physical reality. “It occupies space. It contains energy. Its presence eliminates a true vacuum.”[2] The field creates a "condition in space"[3] such that when we put a particle in it, the particle "feels" a force.
Field (physics) - Wikipedia, the free encyclopedia

7. No, basically it is the intensity of the field that is what decides how things behave. Matter, light everything! When the strenght becomes high the (directional) force of the magnetic might exceed or become of equal strenght as internal interactions. Making large differences possible. The distant is just a measure of the strength of the field.

8. But Star Wars jokes aside what is the 'force'? What is telling the particles to behave in a field, what is transfering this information there has to be a mediator and I'm not so sure a photon can walk up to an electron and say "Excuse me buddy, but you should be coming over here now in this direction, thanks".

9. It is the electromagnetic force, or more classically it is the lorentz force. How a magnetic field influences a charger particle. It also influence an uncharged particle but much much much less. (nuclear forces)

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