Is imagination more important than knowledge?

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Discussion Overview

The discussion revolves around the relationship between electric and magnetic fields, exploring whether one can be considered more fundamental than the other. Participants reference historical perspectives, theoretical implications, and thought experiments related to electromagnetism, with a focus on relativistic electrodynamics.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory reasoning

Main Points Raised

  • Some participants suggest that if a moving electric charge in a magnetic field experiences an electric field, this could imply that magnetic fields are essentially electric fields from different frames of reference.
  • Others argue that the terms "electric" and "magnetic" are context-dependent and that it may be more appropriate to refer to an "electromagnetic field" that encompasses both aspects.
  • A participant questions the meaning of "magnetic" if it can be reduced to interactions between electric fields, suggesting that our perception of magnetic fields is tied to their effects on moving charges.
  • Another participant emphasizes that not all magnetic fields can be described solely as electric fields in another frame, referencing the invariants of the electromagnetic tensor.
  • Some assert that the magnetic field is as fundamental as the electric field, highlighting that relativistic electrodynamics allows for transformations between the two under Lorentz transformations.
  • There are calls for thought experiments to better understand the interactions between electric and magnetic fields, suggesting a fresh perspective on established theories.
  • Participants reference Einstein's quote about imagination versus knowledge, indicating a philosophical angle on the discussion of theoretical frameworks.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the fundamental nature of electric and magnetic fields, with no consensus reached on which is more fundamental or if they are interchangeable in meaning.

Contextual Notes

Some claims depend on specific definitions of electric and magnetic fields, and the discussion includes unresolved mathematical implications related to the invariants of the electromagnetic tensor.

crx
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In 1953 Albert Einstein wrote to the Cleveland Physics Society on the occasion of a commemoration of the Michaelson–Morley experiment. In that letter he wrote:[1]
What led me more or less directly to the special theory of relativity was the conviction that the electromotive force acting on a body in motion in a magnetic field was nothing else but an electric field. - source wikipedia

If a moving electric charge in a magnetic filed will experience (from its frame ) an electric field, and because the only posible way to interact with magnetic filed are by moving charges doesn't this imply that the magnetic filed in reality and from any frame it is an electric filed ?
If the magnetic field it's actually an electric filed we could find its distribution by watching the forces acting on a test charge that approaches a very long straight current carrying conductor. In this way if the charge is negative it will be deviated in opposite direction and away from the current carrying conductor so we can say that the negative test charge experiences a positive electric field from the direction of the "source " of the current in the conductor and from the space behind it and a "negative" electric filed from the "sink" of the current in the conductor.
This COULD mean that the magnetic filed as we represent it as beeing transversal on the current, is not actually transversal but the real filed COULD BE distributed along the current carryin conductor as an electric filed (that can't be shielded for some reason...) and the transversal magnetic filed of lines COULD BE just an apparence of the iron piling pattern not actually real force filed orientation because the iron piling and magnetic filed interaction its also based on moving charges ...
 
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It is better to call any such field an electro-magnetic field. What portion can experienced as "electric" and what "magnetic" will depend upon the motion of the object.
 
But does the word "magnetic" have any meaning if everything regarding to it boils down to interactions between electric fileds?
A stationary observer can see a moving electric filed relative to him as a magnetic filed... The only way for us to experience, to "see", a magnetic filed is to watch its effects on moving electric charges or (test charges, currents). But then a moving charge experiences a magnetic filed as an electric filed. This mean that all we are capable to "see" and experience its an electric filed distributed along the current...Not the ordinary electric filed we know but still an electric filed sorta...
I can't see no magnetic filed that circles an ellectric current ! All I can see its an electric field that somehow only affects other electric charge if the charge is moving. Like walking in the water, you only experience resistance if you are moving...

Am I wrong?
 
crx said:
But does the word "magnetic" have any meaning if everything regarding to it boils down to interactions between electric fields?

You could just as easily ask whether the word "electric" has any meaning if everything related to it boils down to interactions between magnetic fields of moving particles.

Or we could save ourselves some grief, think in terms of electromagnetic fields, and cover both the moving and the stationary cases with a single theory.
 
You cannot describe all B fields simply as E fields in another frame. One of the invariants of the EM tensor is ##E^2-B^2##. For a EM field where that invariant is positive there exists a frame where there is only an E field and no B field, but for a field where that invariant is 0 or negative there is no such frame.
 
Nugatory said:
You could just as easily ask whether the word "electric" has any meaning if everything related to it boils down to interactions between magnetic fields of moving particles.

Or we could save ourselves some grief, think in terms of electromagnetic fields, and cover both the moving and the stationary cases with a single theory.



You could say that its just a point of view...But we start with electric field ! We know that there is an electric filed there from the begining... A magnetic filed would be just the effect of moving electric fields...

Its not a theory Its an observation, relativistic view of electrodynamics...
 
The magnetic field is just as fundamental as the electric field. As DaleSpam noted there are field configurations wherein the magnetic field cannot be made to vanish entirely due to the Lorentz invariant mentioned by DaleSpam. Relativistic electrodynamics does not say that the electric field is more fundamental than the magnetic field, it says that components of the electric and magnetic field can transform into one another under Lorentz transformations.
 
DaleSpam said:
You cannot describe all B fields simply as E fields in another frame. One of the invariants of the EM tensor is ##E^2-B^2##. For a EM field where that invariant is positive there exists a frame where there is only an E field and no B field, but for a field where that invariant is 0 or negative there is no such frame.

Justifying using known electromagnetic theory will not help here...

How about you think of what I said as a thought experiment...
Just imagine the currents the charges...Try to imagine what is going on between two parallel conductros when currents flow in them, how induction can happen between two parallel conductors etc. Ask yourself questions and try to answer to them. Do it like you see them from the first time, start from scratch and let's see where you end up...
 
Such thought experiments, and discussions of said thought experiments, can be found in electromagnetism texts e.g. Purcell chapters 5 and 6. It is simply not true that the electric field is any more "real" than the magnetic field.
 
  • #10
WannabeNewton said:
The magnetic field is just as fundamental as the electric field. As DaleSpam noted there are field configurations wherein the magnetic field cannot be made to vanish entirely due to the Lorentz invariant mentioned by DaleSpam. Relativistic electrodynamics does not say that the electric field is more fundamental than the magnetic field, it says that components of the electric and magnetic field can transform into one another under Lorentz transformations.


So without a Lorents transformation the Universe can't do that trick?

I read many post here from experts but all of you guys when something its not happening as the standard theory predicts you consider it that its wrong... Did you ever think that the theory might be incomplete than the Universe?
 
  • #11
WannabeNewton said:
Such thought experiments, and discussions of said thought experiments, can be found in electromagnetism texts e.g. Purcell chapters 5 and 6. It is simply not true that the electric field is any more "real" than the magnetic field.



Can you do that thought experiment by yourself ? You will only need a paper and a pencil...
 
  • #12
I found this nice quote from Albert Einstein, and I would like to share it with you :

“Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.” Albert Einstein
 

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