# Cleveland Physics Society

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1. Jul 6, 2013

### crx

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 ...

2. Jul 6, 2013

### HallsofIvy

Staff Emeritus
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.

3. Jul 6, 2013

### crx

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?

4. Jul 6, 2013

### Staff: Mentor

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.

5. Jul 6, 2013

### Staff: Mentor

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.

6. Jul 6, 2013

### crx

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...

7. Jul 6, 2013

### WannabeNewton

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.

8. Jul 6, 2013

### crx

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 paralel 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 lets see where you end up...

9. Jul 6, 2013

### WannabeNewton

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. Jul 6, 2013

### crx

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. Jul 6, 2013

### crx

Can you do that thought experiment by yourself ? You will only need a paper and a pencil....

12. Jul 6, 2013

### crx

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