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Re: [Phys-l] Denker zero width puzzle?

Joel's solution meets the specification, but is greatly useful to
Benoit Mandelbrot enthusiasts, I imagine.
Perhaps a straight line would be more useful, (though straightness
was not explicitly required) such as the shortest line segment
which joins two points, each of which equally divides the length of
each line of two parallel lines of finite length.
Even where those parallel lines are not vanishingly thin. :-)

Brian W

At 10:30 AM 10/15/2007, you wrote:
Scroll down for one possible answer????
Presumably vetted by J. Denker














































If you draw a line on the blackboard with chalk, the edge of the line
has zero width. I.e. its boundary
________________________
Joel Rauber
Department of Physics - SDSU

Joel.Rauber@sdstate.edu
605-688-4293



| -----Original Message-----
| From: phys-l-bounces@carnot.physics.buffalo.edu
| [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf
| Of John Denker
| Sent: Monday, October 15, 2007 12:33 AM
| To: Forum for Physics Educators
| Subject: [Phys-l] zero width?
|
| Ben Wittner tells this story:
|
|
| When he was in primary school, the teacher said:
| "Everything has some size. In mathematics, they say a line has
| zero width, but I don't believe it. If I draw a line with this
| chalk, it has some width. If it didn't have any width, it wouldn't
| exist."
|
| At this point Ben pipes up:
| "I can draw something with zero width."
|
| The teacher said:
| "Show me."
|
| So Ben went up to the chalkboard and ......
|
| So the puzzle is: What happened next?
|
| The answers I'm looking for might take the form:
| -- If you think it is not possible to draw something with zero
| width, explain why not.
| -- If you think it is possible, explain the best way to go about it.


Brian Whatcott Altus OK Eureka!