On Saturday, January 11, 2003, at 12:28 PM, Eric Hawthorne wrote:
> ...
>
> This scientific process works pretty well
> but is somehow loosy-goosy and unsatisfying. Do theories which replace
> other older, now discredited theories, keep getting better and better?
> Probably yes.
> But what is the limit of that? Is there one? Or a limit in each domain
> about which
> we theorize?
Sometimes there is a refinement process which looks a lot like
refinement of a computer program, in the sense that more and more of
the desired specifications are met. (This is like a series of subsets
of a set, with each smaller set converging on the "perfect program," a
kind of fixed point for the process. This set-theoretic view has an
equivalent formulation in terms of a sequence of branch points, a type
of lattice. Cf. "Lattices and Order," by Davey and Priestley, for
example.)
Other times science proceeds via substantial paradigm shifts,
well-covered by Kuhn of course. In these "knowledgequake" steps, the
model of gradual refinement is essentially shifted to one where a
change of basis occurs, where the very building blocks are altered.
The transition from Ptolemaic to Copernican, for example, or from
"humors" to "microorganisms" in medicine.
Both relativity (special and general) and QM basically satisfy the
correspondence principle by reducing to the classical theories at low
relative speeds, with ordinary falling objects in gravity fields, and
with macroscopic objects. (QM does not in the sense that many
phenomena--slit and photoelectric, stability of atoms, etc.--have no
classical theory. And electronics are all around us and need QM to
explain. But QM reduces to classical in various obvious ways.)
Hey, I'm not going to write a free-form essay here on science and the
nature of theories, so I'll move on to your next point.
> But hold on, most of the scientific revolutions tell us that we had a
> nice
> theory, but were theorizing about a badly-scoped, badly conceptualized
> idea of what
> the "domain" was. A better theory is usually a better set of formal,
> interacting concepts
> which map to a slightly (or greatly) differently defined and scoped
> external domain than the
> last theory mapped to. None of this is very straightforward at all.
>
> For example, would you go out on a limb and say that Einstein's
> theories are
> the "best" (and only "true") way of modelling the aspects of physics
> he was concerned
> with?
Yes, I would, with some caveats.
His 1905 theory has not been significantly changed, and it has been
tested at a wide range of energies (e.g., slowed decay of muons in
cosmic showers and accelerators, as one example). And his 1915 theory
has been tested in various ways, with gyroscopes in orbit,
astrophysical objects, lensing, etc.
However, a new result could always force changes. So far, these have
not been needed. (Also, there are new solutions to field equations, new
mathematical formalisms like differential forms over standard tensors,
and so on. Einstein did not wrap up all problems, even with
gravitation. This is why much work was done later, and is still being
done.)
And quantum gravity and other "theories of everything" which unite the
known forces, are very much up in the air at this time.
So, yes, relativity was the "best" theory and remains so. Is it the
"only true" theory for the things it covers? Certainly not.
But science is an evolutionary process, in the evolutionary learning
and selection sense. Until something challenges a theory, the theory
lives. Until something better comes along...
> If so, would you be equally confident that his theories cover
> "essentially
> all the important issues" in that domain? Or might someone else,
> someday, re-conceptualize
> a similar but not 100% overlapping domain, and create an even more
> explanatory
> theory of fundamental physics than he came up with? Can we ever say
> for sure,
> until that either happens or doesn't?
No, and I know of no scientists who claim that a theory is complete and
not subject to challenge or replacement by other theories. But theories
which appear to be comprehensive in the way QM (and QED and QCD) and
relativity are, in their domains, are not lightly challenged.
Especially they are not challenge by metapoints about how maybe there
are theories which will someday subsume them.
>
> You can interpret the history of science in two ways: either we were
> just really
> bad at it back then (in Newton's day) and wouldn't make those kind of
> mistakes
> in our theory formation today,
No, I don't think this can be said at all. Classical mechanics _is_
what relativity reduces to at speeds found on earth and in laboratories
prior to the past century.
There's a parsimony issue at work as well. Newton, Laplace, Lagrange,
and all of the other classical mechanics folks might have had some
inkling that they could incorporate "fudge factors" into their
theories, parameters left blank until they could be filled in, but NO
EXPERIMENTS and NO OBSERVATIONS needed such fudge factors. Within the
accuracy of the experiments, there were no epicycles or orbital
corrections needed (not for a long time, not until slight deviations
from theory in the orbit of Mercury showed up, as one example).
And this correspondence is not accidental. This is not like saying the
theory of epicycles is a limiting case of classical mechanics and
gravitation, which it most certainly is not. Let Planck's constant go
toward zero and classical mechanics happens. Let v << c and classical
mechanics happens.
> or you can say, no we're about as good at it as always,
> maybe a little more refined in method but not much, and we'll continue
> to get
> fundamental scientific revolutions even in areas we see as sacrosanct
> theory today.
It took better tools to see into the regimes where the older theories
failed. It will probably take substantial increases in accelerator
energies to see into the regimes where quantum gravity is
evident...some say that short of probing at Planck scales (of length,
energy, time), we will have no way to distinguish amongst competing
theories.
More optimistic folks think we may see some kind of evidence within our
lifetimes.
Certainly we are not in a solipsistic situation where new theories are
easily formulated and knock off older theories without experimental
evidence or unexplained phenomena.
>> I don't understand your "secret cause of asymmetry in the universe"
>> point. We understand some things about symmetry breaking in particle
>> physics theories, via gauge theories and the like. If you want more
>> than this, you'll have to expand on what you mean here.
>
> It is a Koan (kind of). A self-referential, absurd example of a notion
> that an imbalance in a formal symbol system (the words I'm using, and
> the quotes) could possibly be the cause of
> asymmetry in the physical universe.
Probably not, but I won't get into a debate with you on this.
--Tim May
Received on Sat Jan 11 2003 - 16:40:42 PST
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