Truth is ever to be found in simplicity,
and not in the multiplicity and confusion of things.
-- Isaac Newton
[Note:
In using the term “minimalism” in evaluating styles of physics, I am
importing into the philosophy of science a term mostly associated with
the arts. The move may or may not be fruitful. But here is a
well-known parallel move, from Gerald “Mr. Themata” Holton, in The scientific imagination (1978), p. 7:
I have proposed … thematic analysis (a term familiar from somewhat related uses in anthropology, art criticism, musicology, and other fields). ]
The
whole enterprise of physics, from ancient times to today, is itself
in one sense Minimalist, in that it seeks to sweep aside the riot of
epiphenomena, and to discover underlying laws, from which that riot
derives. It does not so much
banish the fullness of reality, as
bracket it: we hope later to derive much of it back, in an explanatory manner. (Note: Not quite the same thing as Reductionism.)
To
some extent, all rational inquiry ‘minimizes’ -- idealizes, works with
toy models, etc. Some more than others -- economics notoriously so,
tossing out so much bathwater that sometimes the baby goes missing.
Others roll up the sleeves of their labcoats and go in elbow-deep to
the mess of reality, little bothering with economy or philosophy.
Chemists, in particular, seem perfectly content to potter about in labs,
to discover stuff, invent stuff, patent stuff. They literally
multiply entities, in that they invent chemicals that weren’t there
before. Whether they thereby multiply them beyond necessity (mustard
gas, thalidomide, napalm, LSD) is a matter of individual taste. But
certainly the ethos is anything but austere.
And likewise, for the most part -- biology, geology, astronomy, engineering, what have you.
But
modern physics raises parsimony to a central tenet, almost the prime
purpose of the whole enterprise as currently understood. This
development being by now taken for granted among those of the guild, it
may not be apparent how odd this really is.
The
goal for some time has been the “Theory of Everything”. This
certainly sounds like a Maximalist program: but really it is not.
For the knights who pursue this grail do not actually intend to explain
any of the things that real people care about and that motivated the
enterprise of physics in the first place: why the sky is blue, why
snowflakes are the way they are, why clouds are shaped that way, what
lightning is all about, why airplanes can fly… (Purported explanations
of these things exist, but the ones I’ve heard seem all fallacious.)
Instead, they want to wrap their arms around a passel of abstractions,
so complex as to leave the plain man -- nay, any but the professional
physicist -- behind many decades ago, and show that, at a still deeper
level, they are all but facets of One Big Thing. (Hedgehog physics, we might dub this.) This is Minimalist, and ferociously so.
It
may be objected: All that is nothing but plain reductionism, which is
simply to say: Science. No call to drag in an arts-related term like
“Minimalism”. -- But I believe there is an aesthetic dimension --
seldom mentioned in journal articles, though over-emphasized in popular
writing -- which lies outside the bare logical necessities. As,
“There
shouldn’t be laws of physics,” Strominger maintains. “There should be
just one law, and it ought to be the nicest law around.”
(Quoted in Shing-Tung Yau, The Shape of Inner Space (2010), p. 14.)
Gerald Holten, characterizing the attitude of Einstein (The scientific imagination, p. 281):
At stake was nothing less than finding the most economical, simple, formal principles, the barest bones of nature’s frame, cleansed of everything that is ad hoc and redundant.
In
his own personal life, the legendary simplicity of the man was an
integral part of this reaching for the barest minimum on which the world
rests.
*
Central
to the program is the “unification” of the various fundamental forces
-- meaning, showing them to be symmetry-broken castoffs of an original
single Force. An analogy in evolutionary biology is explaining
various related species as having descended under various environmental
pressures from a common progenitor. Only -- in physics, the
enterprise is far more audacious than this analogy would suggest, if all
you are thinking of are the breeds of dog, or the various canine
species, or even the various land-mammals. The forces are so
fundamentally different in their phenomenology, that the task is more
like tracing the common descent of the penguin, the echinoderm, and the
paramecium. Or even the mastodon, the gnat-swarm (considered as a
sort of collective entity), and the sand-dune. A tall order.
The
reason so hubristic a program could come into existence despite the
odds, is that it had an early success: Maxwell’s unification of
electricity and magnetism, back in the nineteenth century, truly a
monument of the human intellect. Now, later analysis has suggested that
this success was something of a lucky fluke: in the four macroscopic
dimensions in which we reside, electricity and magnetism are both
expressed by a vector. You can not only analogize these, the one to the
other, but calculate with them in the ordinary way -- say, forming
their cross-product to get the Poynting vector. In higher dimensions,
electricity would be a vector and magnetism would be a tensor, and they
would not play so nicely together.
The
next success along these lines was far spookier: the unification of
electromagnetism with the “weak force”, into an unassuming-sounding
entity called electroweak.
Now, this is far more bizarre than it seems. Electricity and magnetism
were always rather like Batman and Robin, typically showing up
together in the lab. Whereas the weak “force” seems, to my untutored
mind, like a force in some Pickwickian sense, like the “force” of a
metaphor in a poem. A thing more different than electrostatic
attraction or repulsion can scarcely be imagined: it deals neither in
repulsion nor attraction, but rather in a handful of obscure and
scarcely explicable processes such as beta decay. Even to have
conceived the project of their unification was an act of extraordinary intellectual audacity; the eventual success is, well, beyond any but specialist comprehension.
This new composite entity, this hippogriff, the electroweak, was subsequently unified with the “strong force”, yielding the
hyperweak
of today’s Standard Model. The next -- and long elusive -- step, is
the unification of that with gravity. Now, to your average toddler,
the natural analogy would be rather between electrostatic and
gravitation attraction -- both, in their simple nonrelativistic forms,
central forces obeying an inverse-square law But your average
toddler, like your average Nobel-Prize-winner-in-anything-but-Physics,
would be mistaken. And so the torch has passed to an
ever-more-esoteric brotherhood, in particular the magi of String
Theory: pale, spectral beings, who neither eat nor defecate, and whose
results -- well, they do not as yet have anything so vulgar as actual
verifiable physical
results,
mind you, but they do have theories, and conference papers,
incomprehensible to all but the magi. That does not mean they are on
the wrong track; perhaps they, and they alone, are on the right track,
in which case, the more fools we.
A
startling development in some corners of recent physics is an actual
‘Maximalism’ -- basically, the catastrophic breakdown of any
parsimonious project, yet not taken as a reductio ad absurdum of
reductionism itself, but rather embraced, by
amor fati
(a fancy name for making the best of a bad bargain). No longer can
one really -- nor does one aspire to -- explain anything, since
everything that might exist, does exist, and the (now uninteresting)
facts of the matter in our own neck of the woods can be chalked up to
Selection Effect. (We satirized this Rabelaisian
Fay ce que voudras here).
Templeton-Prize winner Paul Davies, in The Goldilocks Enigma (2006), p. 264, takes rather understated notice of this:
The
disadvantage of the multiverse theory is that it invokes an
overabundance of entities, most of which could never be observed, even
in principle. This profligacy strikes many people as an extravagant
way to explain bio-friendliness.
Likewise,
though for different reasons, the earlier Many-Worlds school (or
cabal) of quantum theory, in which entities -- again, entire universes
in this case -- are multiplied, not simply beyond necessity, but
beyond common decency.
The ethos of all this is atheistic -- a-anything,
really. It is perhaps no accident that Hugh Everett, an early pioneer
of many-worlds, was (in Wiki’s words) “a committed atheist". Or that
the thélémisme of the distinguished hexagonal/pentagonal humanist was
taken up with gusto by the diabolist Aleister Crowley, the stench of
whose cinders may occasionally bother your nostrils, whenever a high
wind blows up from Hell.
[Update 27 III 12] Freeman Dyson in the current NYRB,
reviewing a book by Margaret Wertheim about eccentric amateurs:
String cosmology is different.
String cosmology is a part of theoretical physics that has become detached from
experiments. String cosmologists are free to imagine universes and multiverses,
guided by intuition and aesthetic judgment alone. Their creations must be
logically consistent and mathematically elegant, but they are otherwise
unconstrained. That is why Wertheim found the official string cosmology
conference disconcertingly similar to the unofficial Natural Philosophy
conference. The insiders and the outsiders seem to be following the same rules.
Both groups are telling stories of imagined worlds, and neither has an assured
way of deciding who is right. If the title Physics
on the Fringe fits the natural philosophers, the same title also fits the
string cosmologists.
[Note:
Dyson -- a notably fair man -- has long been a fixture of the Institute
for Advanced Studies in Princeton; and the IAS, in recent years, has
been premier in string theory. So Dyson's assessment here is by no
means that of an envious outsider.]
On the extra profusion of different string theories, a
mathematician remarks dryly,
It was hardly an idea calculated to
appeal to a man with a taste for desert landscapes … There are more than 10^500 versions of string theory lounging indolently about.
-- David Berlinski, The Deniable Darwin (2009), p.
532-3
*
It
will sometimes not be obvious, which proposals are Minimalist in
spirit. Thus, imagine some wretched Nominalist, who balks at the
infinite, and proposes that the numbers needed for physics are finite
-- specifically, the field of integers mod a prime p
(necessarily quite large, to accord with observation). Finite’s
gotta be simpler, more minimal, than infinite, right? Roger Penrose
retorts (The Road to Reality (2004), p. 359):
A
physical theory which depends fundamentally upon some absurdly
enormous prime number would be a far more complicated (and improbable)
theory than one that is able to depend upon a simple notion of
infinity.
More precisely: The
problem is not essentially that the number is so large, but rather,
with infinitely many primes to choose from, the choice would seem
arbitrary: in much the same way that the omniscient computer in The Hitchhiker’s Guide to the Galaxy reveals, quite disappointingly, that the Meaning of Life is … “26”.
*
Differing
from a theory-wide programatic theoretical minimalism, is a kind of
personal cognitive-epistemological economy, described by Gerald Holton, The scientific imagination (1978), p. 158:
Fermi
ordered the overwhelming and vast amount of knowledge into a set of
very few principles and ‘cases’, which allowed him to understand almost
any new problem as an example of one of about seven primitive or primary
physical situations. Fermi would return throughout his career to a
listing or digest of the chief ideas in physics, which he had made when
he first organized the field for himself as a young student.
Our own thoughts about such Leading Ideas in other areas, may be surveyed
here.
*
A curious philosophico-cosmogonic anticipation of the TOE vs. Landscape divide goes back several hundred years:
Leibniz
… assure que la perfection de Dieu ne lui permettait pas de procéder
d’autre manière que de la meilleure … mais Thomas d’Aquin sait que,
créant du fini, un Dieu infini pouvait librement créer un nombre
illimité d’univers différents, tous bons et chacun commençant de manière différente.
-- Etienne Gilson, Linguistique et philosophie (1969), p. 163
And
indeed, though Leibniz coinvented the calculus, we must say that, here,
from a mathematical standpoint, it is Saint Thomas who is closer to the
target.
Bonus quote:
Willem de Sitter found an exact
solution to Einstein’s field equation … having no matter at all. … Why should
we be interested in such a universe?
Because the real universe is of rather low density …
-- J. Richard Gott, The Cosmic
Web (2016), p. 16
.
