🚀 go-pugleaf

In article <6NOV199211570602@csa1.lbl.gov> sichase@csa1.lbl.gov (SCOTT I CHASE) writes:
>In article <1992Nov5.212050.25373@murdoch.acc.Virginia.EDU>, crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes...

>>     However, getting back on track it is silly to say that a theory that in 
>>     some sense avoids internal inconsistency has passed some sort of 
>>     valid scientific 'test'.  It's like patting oneself on the back
>>     for not having assumed ii equals 3 and ii equals 5 at the same
>>     time.  
>
>.... However, I assure you
>that it really works that way in particle physics.  Internally consistent
>theories come much more easily in classical physics than in quantum field
>theory.  Over the fifty-odd years of particle physics history, internal 
>consistency has repeatedly been a useful way of discovering new physics.

Let me strengthen Scott's point in a rather backhanded way.  Saying that
"Internally consistent theories come much more easily in classical
physics than in quantum field theory" is an understatement.  In fact, as
I never tire of repeating, none of the quantum field theories that are
used by physicists to do practical calculations have been shown to be
consistent - despite huge amounts of work by very good physicists and
mathematicians.  So in practice one doesn't even seek (demonstrable)
consistency; one simply seeks to avoid the KNOWN causes of (seeming)
inconsistency - this is quite hard enough!  

The other curious thing is that nonrenormalizability and anomalies -- two
things one tries mightily to avoid - have never been shown to lead to
inconsistency in a quantum field theory; they merely indicate the
failure of a certain perturbative method for doing calculations with the
field theory - a perturbative method with rather shaky foundations to
begin with!  Of course, the word "merely" above is tongue-in-cheek,
spoken like an ivory-tower mathematical physicist.  Since all we have of
these quantum field theories is "a certain perturbative method for doing
calculations, with rather shaky foundations," anomalies or
nonrenormalizability are utterly crippling at the present time.  One can
imagine a future in which nonlinear analysis is much more sophisticated
than it is now, in which one could prove the consistency of interacting
quantum field theories, perhaps even some that are nonrenormalizable or
have anomalies... at this point, we can only guess.