From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: STRUCTURE OF TIME
Organization: University of Virginia
Date: Fri, 9 Oct 1992 15:43:45 GMT

In article <1992Oct09.134954.35485@watson.ibm.com> platt@watson.ibm.com (Daniel E. Platt) writes:
>In article <1992Oct8.212221.5633@murdoch.acc.Virginia.EDU>, crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
>|> In article <1992Oct08.200637.162851@watson.ibm.com> platt@watson.ibm.com (Daniel E. Platt) writes:
>|> 
>|> >|> >A gedanken experiment is an act of faith.
>|> >|> 
>|> >|>      A gedanken experiment is a construct that admits falsifiability if
>|> >|>      it is physics.  It is not an act of Faith.
>|> >
>|> >Now this I feel misses the point.  I think gedanken experiments are
>|> >ways of exploring the consequences of principles or theories in a
>|> >more practical setting.  Einstein's relativistic railroads were never
>|> >things that one could do falsifiable tests on.  However, they did
>|> >provide a good way to articulate consequences.
>|> 
>|>      I feel compelled to point out that falsifiability does not
>|>      necessarily imply that you need to perform the experiment, or even
>|>      that you know how.  A mental construct can admit falsifiability, even if
>|>      you do not actually know how to falsify it.  If it does not
>|>      admit falsifiability, it is not physics.  
>|> 
>|>      On a more concrete level, these consequences of which you speak
>|>      can falsify your gedankenexperiments.  The ability is sufficient.
>
>No.  A Gedankenexperiment can never falsify anything.  It can be used to
>analyze consequences.  If those consequences violate other experimental
>results, then it is the comparison with THOSE real experimental results that
>falsifies the theory.

     No one said that a gedankenexperiment can falsify anything.
     The point is that a gedankenexperiment is falsifi*able* if
     it is physics.  It can either be consistent with what we
     see, or not.

>|>      I don't want to go too deeply into religion, but I do hope that you'll 
>|>      understand.  
>|> 
>|>      No text or concept taken on Faith has ever been falsified, by physics or 
>|>      by anything else.  Try to rid yourself of the rules by which you
>|>      are thinking of this.  If one of my tenets of Faith was that the moon 
>|>      was made of green cheese, no amount of 'evidence' to the contrary
>|>      would suffice to falsify this tenet, simply because evidence does
>|>      not matter with Faith.  Evidence has absolutely nothing to do with 
>|>      Faith. 
>
>A more liberally theological position would disagree with your definition
>of faith.  However, the same problem (situation?) exists in physics today,
>when people insist that my coffee cup has a state vector.  Insisting that
>the state vector is some substantial thing is a leap of faith, and is
>not falsifiable (both those who consider state vectors to be descriptions
>and those that believe the coffee cup HAS a state vector would agree on
>their observations, and would construct substantively similar descriptions
>of the physics).

     In the abscence of possible experimental determination, discussion of
     the 'reality' of the state vector is metaphysics, not physics. 

>On the other hand, when I was growing up, a friend of mine said they couldn't
>have flown to the moon since 'heaven was in the way.'  Now THAT's a statement
>of faith along the lines you're speaking of.  My response was, 'well, where
>did they go then?'

     The obvious response is 'Not to the moon, appearances can be deceiving.'

>|>      All of these descriptions are certainly falsifiable in that they
>|>      are all tentative.  They do not generally fall into the category
>|>      of Faith.
>
>As descriptions, they are falsifiable.  Investing them with concrete reality,
>beyond simple description, is not falsifiable; it also does not contribute
>or detract from the descriptive power of the concepts.

     Investing them with 'concrete reality' is metaphysics, not physics.

                                  dale bass
-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926