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[Phys-L] Re: Fields etc

Jim Green wrote:

At 13:02 25 03 2005 , the following was received:

Go back to basics, in this case the definition of "field". Charged
objects, in a certain region, experience forces that are proportional to
the charges, and for each object there is a unique force vector at each
point of the region. Divide the force vector by the associated charge on
the object. The resulting set of vectors is called the "vector field in
the region". Is it real?

Well, Jack, one small quibble: We don't discover a "unique force vector";
we invent the idea of a vector with the wild hope that our calculations
will be made easier. If we divide a set "force vectors" by the associated
charge, we have the _invented_ concept of a "vector field." We have
not _discovered_ a field. Nevertheless sometimes we reify the idea of a
field. This is just fine as long as we remember that this is an invention
not a bucket of stuff we have discovered.

We sometimes _reify_ the concept and then argue whether it is "real."


OK, I give up! After reading this thread, my question is, What is real?
I thought the concept and application of vectors was well established
before it was ever applied to the definition of the Electric field.
James Mackey
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