Re: [Phys-l] Paradoxes, or not. (Was: invariant mass...)

[Hugh Haskell <hhaskell@mindspring.com>]

At 1:50 PM -0700 2/26/08, John Denker wrote:
> To answer my own rhetorical question:  I think teaching
> paradoxes (in an introductory course) is the epitome of bad
> pedagogy.  It just sows confusion.  Where's the fun in that?  
> Maybe if I were a sadist I would enjoy tormenting the students. 
> Maybe if I were really, really insecure I would need a way
> to confuse the students so I would look smart by comparison. 
> Either way it sounds like bad pedagogy to me.
I think it depends on how you do it. If you lead the students to 
think that you have stated the problem correctly, then you do confuse 
the students, but if you put the problem out in the form of how 
different observers see the same situation, then it becomes an 
"apparent paradox," which, when the problem is properly stated, goes 
away. So using this technique enables students to realize just what 
you said--a correctly stated problem cannot lead to a paradox.

In my use of apparent paradoxes in the classroom, the emphasis is on 
what the different observers see and why that shouldn't be surprising 
if you describe the situation correctly. I also use the idea of 
apparent paradox to establish why relativity works only along the 
line of motion and not transverse to it. I think the way the word 
"paradox" is being used here is more closely related to "proof by 
contradiction," than to the more traditional definition of paradox.

Hugh
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Hugh Haskell
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<mailto:hhaskell@mindspring.com>

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