From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: GR with no Einstein? (Was: Re: No big crunch?)
Organization: University of Virginia
Date: Mon, 9 Nov 1992 18:24:46 GMT

In article <COLUMBUS.92Nov9104245@strident.think.com> columbus@strident.think.com (Michael Weiss) writes:
>Cameron Randale Bass writes: 
>
>   >>     Suppose, as I have been, that you *don't even have* GR.
>   >>     In 1906, there was no certainty that GR would be developed.
>   >>     In fact, if Einstein had died in 1906, I'm quite sure it 
>   >>     wouldn't have been.
>
>   In article <1992Nov6.232435.15628@galois.mit.edu> jbaez@riesz.mit.edu
>   (John C. Baez) writes: 
>
>   >Oh good, let's argue about this, since it is utterly contrafactual.  I'm
>   >sure GR would have been developed (though not in 1906!)....
>
>In fact, there was a fairly extensive thread on this topic about a year
>ago.  Without trying to summarize, let me repeat 4 points people made:
>
>  (2)	Other very different paths to GR exist.  MTW mentions a "graviton"
>    	based approach, worked out apparently by Feynmann.  You don't get a
>    	consistent unification of QM with GR, but you can somehow tweak out
>    	Einstein's field equations.  This was cited as an argument that GR
>    	was "inevitable", once quantum field theory was developed.

     It is wonderful what we can do once we know the 'answer', no?  Seems
     to me that quantum field theory would have been the biggest impediment
     to the development of GR that we know of.

     Though many people were working on gravitation, and always had been
     working on gravitation (and there are still people working on 
     alternatives), it wasn't like there was any vastly compelling reason to 
     overthrow Newton.  With the exception of brief mentions in 1907 and
     1908, Einstein himself did not begin publishing in earnest 
     on GR attempts until the turn of the decade.

>  (3)   One does have to decide what "GR would have been developed" means.
>    	Would it count to have a theory equivalent to GR, not generally
>    	accepted but merely one of a welter of competing theories?

     Absolutely, if we had had to wait until renormalizability
     became a criterion for physical law, I suspect that *no* such
     theory would have become accepted.  The wondrous nature of scientific
     theory being what it is, there has been a huge number
     of formulations that can be recognized in retrospect as being bits
     and pieces of modern theories.   This does not mean that the
     modern formulations were inevitable.

>  (4)   And finally, from Twain we can crib the granddaddy of
>    	counter-factual assertions:  If Walter Scott hadn't written any
>    	novels, there wouldn't have been a Civil War.  [OK, that's not
>	exactly was Twain said.]
>

      No, actually it's more like 'If Walter Scott hadn't written
      any novels, there wouldn't be any Walter Scott novels'.

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