Spam Alert: Re: [Amps] The Philosophy of Science

Gary Schafer garyschafer at attbi.com
Tue Feb 11 20:57:58 EST 2003


My vote it that there is an excessive amount of ego bolstering going on. 
Nothing more nothing less.

73
Gary  K4FMX


MorgusMagnificen at aol.com wrote:
> Okay, I sincerely apologize for the aggressive broadside. I am just sick and 
> tired of hearing all of the distortions of theoretical science and 
> engineering that I hear EVERYWHERE . I hoped this group would have a little 
> more understanding of it. If your world ends at the 4th significant figure, 
> fine for you. For many others, the action doesn't even begin until the 6th - 
> or 10th.
> 
> One statement by you and others ( in some of those OTHER armchairs) regards 
> the term 'computer modelling'. There is somewhat of a semantic problem here, 
> as follows. The computer models which we use are EXACT, precise physical 
> devices whose electronic equations we can write precisely. We can then apply 
> them in circuits and solve the circuit equations to any desired degree of 
> accuracy. In the limit (this is a profound mathematical statement, which 
> forms the basis of all numerical computation algorithms) these solutions 
> converge to the exact answer (if the algorithm designer has not screwed up!). 
> 
> The approximation comes in when we attempt to apply this exact model to a 
> practical circuit. Again, the degree of agreement between the two is limited 
> by our ability to measure the real-world components, which we all know has 
> practical as well as theoretical limits. So it is not the modelling process 
> which is 'inexact'. The error comes from our measurment limits, which we 
> know, control, and can accurately predict.
> 
> The laws of physics themselves are models. I posed the very relavent question 
> "is the formula R=E/I an exact model" and no one wants to take a stand on 
> that, the most basic of all of our electrical 'laws'. That we can approach 
> exactness only in the limit sense does not make it any less useful to us.
> 
> I want to close this (although I am sure you would like to conrtinue to hear 
> me rant) by going back to where it began, and show how all of those who have 
> argued against me have badly distorted the issue. It started when Jeff posted 
> a very simple solution to a somewhat complex problem - the calculation of 
> filter capacitance in a PS. I was, like others, initially suspicious of his 
> results but I wanted to check it out as accurately as possible before 
> attacking his work. To do so, I made the most accurate calculation I could of 
> the same problem, so that if I were to raise a complaint, no one could accuse 
> me of basing it on an inexact calculation (i.e. an approximation, with which 
> the older power supply literature is filled .) So by comparison, my 
> calculations were so precise (let's say they produced results accurate to 
> .01%) that they were effectively exact in comparison to older data. To most 
> engineers I know, that constitutes an exact calculation. (What you may not 
> realize is that this 'old' data which I always refer to was based on highly 
> approximated models - with our modern computers we do not have to severely 
> approximate our models.)
> 
> Does it really change anything if I change the wording to read 'highly 
> precise'  calculations instead of 'exact'? Would it convey any more or less 
> useful information to you? Would it make any difference when you finally get 
> back to your workshop to build your amp, for which you will be doing well to 
> get a filter cap that is within 10% of the predicted EXACT value?
> 
> I would like to ask for a polling by everyone reading this (if you are still 
> awake) on the following: Does the fact that my calculations were terminated 
> at an accuracy of .01%, as opposed to the known errors of 10% or greater  in 
> old data, mean that my calculations are not exact? And if not, how precise 
> would I have to make them  in order to qualify as a standard against which to 
> measure simple approximated calculations, such as Jeff's? Does it bother you 
> that I use the word 'exact' in the context of "high-accuracy, so high that 
> its estimated error is too low to be of  any concern" ?.
> 
> Eric K8LV
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> 





More information about the Amps mailing list