🚀 go-pugleaf

In article <snodgras.716184184@crash> snodgras@crash.cts.com (John Snodgrass) writes:
>In <1992Sep8.010243.21974@unixg.ubc.ca> ramsay@unixg.ubc.ca (Keith Ramsay) writes:
>
[ ... ]
>>The details of its mechanism are not especially relevant to an
>>exposition of relativity, however, since the same correspondence
>>between the activity of stationary and moving bodies is supposed to
>>hold for any other kind of system, even if it doesn't operate by
>>springwork.
>
>      Yes, this is what makes it mystical. It doesn't involve physical
>interaction as a cause, therefore it is placing mathematical notions (which
>are meant to be descriptive) in the role of cause. It's an advanced form
>of superstition. Numerology with abstract variables.

I think there is a difference between saying "observably, things work in a
way that I can summarize with Lorentz symmetry, even if I don't know all the
details right now" and saying that "the lorentz symmetry *causes* things to 
work in a certain way".  The former is what physicists would assert, and
doesn't seem mystical to me.  It is nothing more than a concise summary of
experiments to date -- it certainly does not rule out later experiments 
invalidating it to some degree (as happened to Galilean symmetries).

>>The crucial fact, from a modern point of view, is the kinds of
>>symmetries which (all known) phenomena of nature are found to have.
>
>      This is the heart of the myth. Nature may or may not possess symmetries.
>IMO it does not. Just as it does not possess straight lines or perfect
>curves or dodecahedrons. But scientists are always wishing it would, because
>then a description would fit nicely into a chalkboard formula, which is
>the theoretical physicist's idea of paradise -- especially if he personally
>is the one to discover that formula. This is what drives this mystical hunt
>for the 'cosmic answer' in mathematical terms. It'll never happen. Nature
>is not that way.
>
>      The typical example of failure of symmetry is the once-vaunted
>conservation of parity. Scientists spent 25 years or so seeing this principle
>at work -- the principle which never existed. Did they learn their lesson?
>Hah-hah.

Parity is a perfectly valid symmetry in the areas it was tested in at the time:
(strong) nuclear and electromagnetic interactions.  It was generally assumed 
(with a certain amount of hubris, I suppose) to be a good symmetry of all 
interactions, even though not fully tested.  But, eventually, along comes a
couple of guys to check out all the experiments performed to date and point
out that parity had *NOT* been tested in weak interactions, and that it might
*NOT* be a symmetry there.  And, indeed, right after Lee and Yang's paper, the
experiment was done to prove that weak decays do violate parity.

[So saying that people spent 25 years seeing a principle at work that never 
existed is misleading.  It was seen working in electromagnetic and strong
interactions, and assumed to work in weak interactions but certainly never
seen there.]

So what is the lesson here?  That scientists get used to ideas and have a hard
time seeing around them (recognizing their limits)?  Undoubtedly; few would 
deny this.  There are trends and fashions in theoretical physics as in 
clothing.  It would be nice, perhaps, if scientific bandwagons weren't so 
readily jumped upon, but that is a lot to ask of any human endeavor.  And yes,
many theorists would prefer nature to have nice perfect symmetries that fit
in chalkboard formulae.  Searching for the simplest (a human concept)
description of the universe doesn't strike me as a bad thing, since the
description is for us humans.  In any case, few successful theorists are 
inextricably bound to such ideas, and there will be young rebels once in a 
while to shake things up.

But your first statement in the quoted paragraphs is just wrong:
>      This is the heart of the myth. Nature may or may not possess symmetries.
>IMO it does not. Just as it does not possess straight lines ...

The simple fact is that Nature does have a lot of symmetries.  Many are known
to have limited domains of usefulness.  Treating space as homogenous works
when the smallest volumes are large enough to cover several superclusters or
something.  Parity is a symmetry for electromagnetism and the colour force.
CP works for electromagnetism, the weak force to corrections of .1%, and maybe
the colour force.  So Lorentz symmetry seems generally applicable today, but
even if it is shown to fail in some domain, it will still work in the areas it
works today.  And people will still say that these interactions "have Lorentz
symmetry" (in domain X).  Nature possesses Lorentz symmetry (in domain X).

>      Antimatter is the same blunder. In fact, no such thing as antimatter
>(as the term is taken) exists. You have a particle with a few (very few)
>properties. You discover another particle where all the (miniscule number of)
>other properties appear the same or opposite. Voila! Antimatter! Then they
>can't understand where all the antimatter went, given it must have been
>created in the big bang in equal quantities. But, sure, they've cooked up
>plenty of explanations. Fantasies built on fantasies. These theories are like
>snowflakes built around tiny particles of data. Very pretty, but a little
>sunlight and they melt right away.

Well, please show us the sunlight.  You've argued the sunlight may exist, and
we all agree.  The only difference seems to be that most scientists prefer to
find the sunlight by assuming the symmetries are there and pushing the
theory to the experimental limits, in hopes that something will break.  That
way they might have clues about where to look for a better theory.  You seem 
to think that by excoriating physicists for their endeavors, someone will
suddenly wake up and realise some fatal flaw in all modern theories.

I've probably missed it, but I don't recall seeing a clear explanation of
precisely what we should be replacing the current practices with.

>[...] Einstein cashed in on that need and converted humanity
>by a cultural transformation. His concept of matter was, compared to the
>notion you just described, shall we say _superficial_....

Why do you keep bringing up what Einstein thought?  He may well have
superficial conceptions or motivations compared to nowadays.  So what?  He
wasn't a god.  Interpretations and motivations change and sharpen over time
for all theories.  One of my pet peeves is that Dirac's original interpretation
of his equation is vaunted as a superb "prediction" of antimatter.  It's really
nothing of the sort -- it's a half-cocked attempt to explain away some
embarrasing features of a nice theory.  Once reinterpreted as a field 
equation, the embarrasment goes out of the features and the theory is 
beautiful.  

The point being that original interpretations and motivations don't need to
be convincing sixty years later.  The important thing is that the equations
capture the result of some experiments -- the meaning of them can be dreamed
up later.

>>ramsay@unixg.ubc.ca
>
>      John E. Snodgrass [snodgras@cyber.net]
-- 
Steve Robbins  --  steve@nyongwa.cam.org
I asked Hank Williams "how lonely does it get?"
Hank Williams hasn't answered yet.