Re: cavendish expt

[Brian Whatcott <betwys@DIRECTVINTERNET.COM>]

At 07:15 PM 12/2/02, John Denker, you wrote:

> It would be amusing to see how small you can
> make the [Cavendish] apparatus.  I'll bet it wouldn't be
> too hard to make it smaller than a breadbox.
> You can get some very small fibers cheaply
> and easily as follows:  Go down to the boat
> store and get some good Dacron kernmantel
> rope. Cut through the outer braid with a razor
> knife.  Pull.  Inside you will find angel
> hair, so fine that a single strand can't
> be seen unless the light hits it just right.
> One strand can only support a few grams.  I
> haven't measured or calculated the torsional
> spring constant, but it must be reeeeally
> small.
>
> =========================

Building on this suggestion....
It is exceptionally easy to make a functional
M-M interferometer, with a coherent light source.
You could move a test mass with a micrometer screw
and watch a fringe move, or visualize the period of an
oscillation which has a really quite small amplitude.


Brian Whatcott
  Altus OK                      Eureka!