Field is something more than just a region

  • Thread starter benzun_1999
  • Start date
  • Tags
    Field
In summary: I guess you refer to a definition that appears in some school textbooks. "The region where magnetic forces appear is called the magnetic field" or similar. I think this is a nonsensical, misleading statement.This is a good point. A field without waves is nonsensical, right? And historically, it has been called a 'field'. Thanks for your input.
  • #1
benzun_1999
260
0
Hello,

I believe that a field is something more than just a region. I feel it has something that we all don’t know. If anyone knows more in this topic can they share it?

-Benzun
All For God
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
A field in theory is defined to be a something (number, vector, etc.) which has a value at each point of space (or spacetime in relativistic theories). So it's just like a function, f(x,y,z) where the value of f could be a number or a vector or spinot or whatever.

Physically you go anywhere and measure the intensity of a field and you get an answer. At different points the intensity could be different. The temperature of the air is an example. If it's a vactor field, what you experience will be a force (like attraction near a magnet).

From the point of physics the most important additional property a field has is symmetry. The values of the of the field don't change if you change coordinates in various ways. This leads to physical laws.
 
  • #3
benzun_1999,
I guess you refer to a definition that appears in some school textbooks. "The region where magnetic forces appear is called the magnetic field" or similar. I think this is a nonsensical, misleading statement.
selfAdjoint gave a correct definition.

And why is it, historically, called a 'field'?
Imagine you use a grid of points, and draw from each point a short arrow in the direction of the observed force, with a length proportional to the force's absolute.
You get a pattern much resembling a field of corn plants or so, which are being bent in different directions by the wind.
I guess that is why, historically, it has been called a 'field'.
 
  • #4
thanks...but...need more help

Thank you for helping me, I feel that a magnetic field is a region where a special kind of wave travels. these waves are only created when an object is placed in it. These waves have alternating energy, frequency. the frequency keeps increasing.

-Benzun
 
  • #5


Originally posted by benzun_1999
Thank you for helping me, I feel that a magnetic field is a region where a special kind of wave travels. these waves are only created when an object is placed in it. These waves have alternating energy, frequency. the frequency keeps increasing.

-Benzun

What physical phenomena can you cite for this description of the magnetic field? Why do you think there is a frequency and why do you think it is increasing?
 
  • #6


Originally posted by benzun_1999
I feel that a magnetic field is a region where a special kind of wave travels.
I disagree. I say, you can have a field without a wave. Because, a wave is something that shows some change with time. But you can have fields that don't change with time (stationary fields). Take a magnet. Cover it with a sheet of paper, and scatter iron filings onto it. What you see, is a pattern of lines giving a rough representation of the magnetic field. No change with time, there. So, no wave.
these waves are only created when an object is placed in it.
Placed in what? I think you say "A field is something that creates waves when an object is placed in it". That, to me, is rather the definition of a medium, not a field. Water may create waves when something is thrown into it. Water is a medium, not a field.
These waves have alternating energy, frequency.
Careful. A wave can have a frequency, OK, but what do you mean by 'alternating energy'? Energy is a property of a physical system - what system are you talking about? 'Alternating' may mean, it changes sign as time proceeds - so 'alternating energy' would mean, positive now, and negative later, and zero in between. Are you sure you mean this?
the frequency keeps increasing.
It does if something oscillates faster and faster. But that has nothing to do with fields, does it?

Please excuse if I sound unfriendly - don't mean to. I'm not a native speaker. Just trying to be helpful.
 
Last edited:
  • #7
I disagree. I say, you can have a field without a wave. Because, a wave is something that shows some change with time. But you can have fields that don't change with time (stationary fields). Take a magnet. Cover it with a sheet of paper, and scatter iron filings onto it. What you see, is a pattern of lines giving a rough representation of the magnetic field. No change with time, there. So, no wave.
What would you expect those iron filings to be doing if the field had waves? Jiggle?
I fail to see how this little experiment suggest that a magnetic field is not a wave, or has no waves.
 
Last edited by a moderator:
  • #8
OK, bad example, maybe. I admit a field is a theoretical construct, so we can't prove or disprove any field properties by experiment. Still, you can define a stationary field - while a wave in my understanding is not stationary but time-dependent.

I guess benzun_1999 is wondering how a magnet or charge can influence a body at a distance, even thru a vacuum. I guess that's why he says 'a wave travels'. Sure it's mysterious how one body can affect another when there's 'nothing in between'.

I think we are takling about 2 different questions:

Question 1: How can we describe mathematically the influence of one body on another, distant body? Answer: By fields.

Question 2: Why does this influence occur? Well, there have been many answers to this: Faraday's mechanistic ideas, ether theories, modern gauge-invariance arguments, and so on. I just think 'a wave travels' is not a good answer, since there is no experimental evidence for this.
 
  • #9
Or "a boson travels"? The boson being the quantum of the field.
 
  • #10
thanks...but...need more help

i thank you for helping me to overcome the confusion i had i will be happy if someone tell me more about what is in the field ?
 
  • #11
Does field have an end ?[?]
 

1. What is meant by "field" in this context?

In this context, "field" refers to a specific area or subject of study, typically within the scientific or academic community.

2. How is a field different from a discipline or a profession?

A field is a more specific and specialized area of study within a larger discipline or profession. For example, biology is a discipline, while marine biology is a field within that discipline.

3. Can a field overlap with other fields?

Yes, it is common for fields to overlap with each other. This can lead to interdisciplinary research and collaboration between different fields.

4. Why is it important to recognize that a field is more than just a region?

Recognizing that a field is more than just a region helps to acknowledge the depth and complexity of a particular subject of study. It also allows for a better understanding of how different fields may intersect and contribute to a broader understanding of a topic.

5. How can one determine the boundaries of a field?

The boundaries of a field are often determined by the specific questions and problems that are being addressed within that field. These can change and evolve over time as new research and discoveries are made.

Similar threads

  • Quantum Physics
Replies
3
Views
718
Replies
4
Views
835
  • Quantum Physics
Replies
1
Views
735
Replies
10
Views
940
  • Quantum Physics
Replies
3
Views
134
Replies
5
Views
849
Replies
11
Views
612
Replies
7
Views
1K
Replies
31
Views
2K
Back
Top