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*From*: James Mackey <jmackey@HARDING.EDU>*Date*: Sat, 26 Mar 2005 10:50:19 -0600

Jim Green wrote:

At 13:02 25 03 2005 , the following was received:OK, I give up! After reading this thread, my question is, What is real?

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."

Jim

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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**Follow-Ups**:**[Phys-L] Re: Fields etc***From:*Rodney Dunning <rdunning@BSC.EDU>

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