🚀 go-pugleaf

Cameron Randale Bass writes: 

	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.

Others did, however (e.g., Nordstrom, and someone else whose name I
forget)--though I forget exactly when.  Every couple of weeks, someone in
this newsgroup seems to rediscover that instaneous action at a distance is
incompatible with SR-- I don't think it required an Einstein to realize
that Newtonian gravitation needed modification.  It is worth noting however
that physicists in the period 1905-1915 had no difficulty coming up with
several non-equivalent modification of Newton's law, compatible with SR.

As I recall the previous incarnation of this thread, people tended to one
of two extremes:

    (a)	"Historical determinism": since GR is "correct" (whatever that
    	means), we'd have it by now, by hook or by crook or by Hilbert (or
    	Wheeler, or ...).  And if we didn't have GR, it would be because we
    	had the correct theory of quantum gravity instead.

    (b) "Einstein's inhuman insight": the road Einstein took to GR was so
    	unique (as becomes even clearer when it is compared with other
    	contemporary efforts), and the voice of experiment so muffled, that
    	GR would have languished undiscovered, perhaps for hundreds of years.

Elaborations of (a) frequently contain the unstated assumption that the
rest of physics would have flowed undiverted along its historical banks
even if Einstein's discovery of GR was deftly plucked out.  I find this
dubious, since (for example) Weyl's pioneering work on gauge symmetry was
directly inspired by GR.

If I seem to be fence-sitting, it's because I am.  Perhaps without
Einstein, the wave function wouldn't have collapsed and GR would be
|discovered> + |undiscovered> }}:\)

I wrote:

  (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.]
    
Dale replies:

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

Just to be quite clear: Twain actually said something closer to: The
attitudes in the South before the Civil War was so shaped by Walter Scott's
novels, that he was in a way partly responsible for the War.  (That's not a
verbatim quote.)  Some logician paraphrased Twain's remark as above, as an
example of an "if-then" statement that one might want to disagree with.
Of course, the non-subjunctive version:

    	If Walter Scott didn't write any novels, then there wasn't any Civil
    	War

is true according to the usual rules of the propositional calculus.