Re: ATM lies, damn lies, and mirror tests

[Bratislav Curcic <epabcc@epa.ericsson.se>]

Bill,

I am sorry that in the end it looked that I have picked on you;
I certainly did not, nor I tried to be 'sarcastic critic'. 

If something CANNOT be stiched together because it is fundamentally
flawed, how would YOU say it ? I have been accused before of saying
it 'too much like it is'. That's how I am. Take it or leave it.
But if you felt offended by any part of my post I offer my public
apology here.

> The reason for this response is attitude. We would still be hunting with bows
> and arrows (they were tried and true in their time) instead of modern rifles
> with telescopic sights, if the attitude had been that the mechanical
> difficulties of making an effective rifle were too complex to master.

I guess we would be 'still hunting with bows and arrows' had not we
developed exact mathematical apparatus and scientific method. We can
experiment randomly with various Formica patterns for Dob bearing, for
example (even that involves some scientific approach), or play with
ways to make this ot that part of a telescope. But testing optics MUST
have mathematical 'backup' and sound physical concept behind it. Just
look at any recent publication on modern optics, or even quite old ones
(Schroeder's book contains works of Schwartzchild et all from beginning
of the century). Boring, eh ?  Maybe, but it NEEDS to be like that.
Just because we have long ago passed the 'bow and arrow' phase. We have
most powerful tools placed in our hands (calculus, finite element
analysis and let's not forget computers) to evaluate the idea fom the
beginning and model our dream into something that has great chance to
work when put together in 'real life'. Even then people make mistakes
(cold fusion etc.).

> The development of new tests or techniques in mirror making don't require
> negative sarcasm to demonstrate the brilliance of the critic. Instead it
> needs the application of grey matter to overcome the obstacles and to produce
> something that works better than what we've been doing for more than a
> hundred years.

Pardon me for being simplistic here, but lets say that I have this
wonderfull idea on making the car engine from wood. Great stuff, much
lighter than metal, can be done in home workshop with hand tools. Would
you back me up and 'apply the gray matter to overcome the obstacles' ?
No, you'd say :  this guy is a loonie and probably not even bother to
tell me so.  
I'm not saying that your testing idea is ridiculous, I'm just saying it 
has fundamental flaws and it is far too difficult to execute with today's
technology. 
Besides it DOESN'T offer anything that Foucault test hasn't got aready.
It has far less sensitivity (being at focus instead of COC), doesn't 
allow you to check more than about 1mm square at the time, involves 
complicated calculations to reach the possibly wrong conclusions,
while Foucault is wonderfully natural and intuitive, and lets you inspect
whole mirror at once. 
The question here isn't 'HOW TO IMPROVE', the question is 'WHY' ?

Best regards,
Bratislav