Cecil Moore wrote:
But the rules for black boxes do not allow measurements
on the inside. This is how they help clarify the thinking.

So instead of sweeping technical facts under the rug,
you hide them in a black box. In both cases, the only
apparent purpose is to maintain ignorance.

It seems that whatever part of the system you don't
understand, you draw a black box around it so you
don't have to understand it.


No, it is a perfectly normal technique to test a theory or model. The
black box reveals just enough information to solve the problem, and
nothing more.

In this particular case, the impedance at the terminals of the black box
is the only *necessary* information to solve the transmission-line
problem (in the steady state, at one frequency). It is not necessary to
know how that impedance was created.

Conventional transmission-line theory handles this situation
effortlessly, thus proving that no more information is needed. Any
theory that claims to need more information has failed the test - for
somewhere it has a soft centre that means it cannot be trusted.

Professional scientists and engineers are quite ruthless about this.
They don't wait for other people to propose such tests - they do it
themselves, beating hardest on their own ideas, to find out what they're
good for and where the limits are. Any ideas that don't stand up to this
treatment are ruthlessly discarded.

That isn't always easy, but a professional scientist or engineer has to
have the clarity and integrity to know when it has to be done. That is
why the professionals are very careful not to keep ideas as pets. As in
farming, it's only the amateurs who can afford that self-indulgence.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek