MODERN COSMOGONIES
By the Same Author
A POPULAR HISTORY OF ASTRONOMY DURING THE NINETEENTH CENTURY
FOURTH EDITION.
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PROBLEMS IN ASTROPHYSICS
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THE SYSTEM OF THE STARS
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'_The world's a prophecy of worlds to come._'--Young
MODERN
COSMOGONIES
BY
AGNES M. CLERKE
HON. MEM. R.A.S.
AUTHOR OF
'A POPULAR HISTORY OF ASTRONOMY DURING THE NINETEENTH CENTURY,'
'THE SYSTEM OF THE STARS,' 'PROBLEMS IN ASTROPHYSICS,'
AND OTHER WORKS
LONDON
ADAM AND CHARLES BLACK
1905
PREFACE
Of the sixteen chapters constituting this little work, thirteen have
been published as a series, begun in _Knowledge_ and continued in
_Knowledge and Illustrated Scientific News_, and to the proprietors of
those journals, for their courteous permission to reprint them, I offer
my sincere thanks. Three additional chapters, equivalent to, though
not identical with, those that now appear, formed an integral part
of the original plan of the book, now presented to the public in the
hope that it will enable general readers to follow, with the profound
interest it should inspire, the course of modern inquiries regarding
the origin of the world. Their advance is by no means smooth or facile.
Many difficulties and perplexities are encountered in the attempt to
get back towards the beginning of things. Some of the old tracks, too,
have been torn up by the pioneers of twentieth century science, and
the process of constructing new ones, which shall lead further into
the unknown fore-time, is slow and laborious. But the rail-head in the
desert is a peculiarly suggestive place of pilgrimage, and several such
outlying posts and temporary halting-places are more or less vaguely
localized in the following pages.
London, _November, 16, 1905_.
CONTENTS
CHAPTER PAGE
I. FROM THALES TO KANT 1
II. THE NEBULAR HYPOTHESIS 21
III. CRITICISMS OF THE NEBULAR HYPOTHESIS 39
IV. THE NEBULAR HYPOTHESIS VARIED AND IMPROVED 60
V. TIDAL FRICTION AS AN AGENT IN COSMOGONY 83
VI. THE FISSION OF ROTATING GLOBES 100
VII. WORLD-BUILDING OUT OF METEORITES 118
VIII. COSMOGONY IN THE TWENTIETH CENTURY 135
IX. PROTYLE: WHAT IS IT? 150
X. UNIVERSAL FORCES 166
XI. THE INEVITABLE ETHER 183
XII. THE FORMS OF NEBULÆ 199
XIII. THE PROCESSION OF SUNS 216
XIV. OUR OWN SYSTEM 232
XV. REMNANTS AND SURVIVALS 250
XVI. LIFE AS THE OUTCOME 265
INDEX 283
MODERN COSMOGONIES
CHAPTER I
FROM THALES TO KANT
Very few even of the most savage tribes are content to take the world
just as it is without speculating as to how it came to be. For time
has three dimensions--past, present, and future--and we can no more
restrict our thoughts within one of them than we can exist corporeally
in Flatland. We are, indeed, told that the Abipones and Esquimaux
refuse to trouble themselves with questions of origin, on the ground
that the hard facts of life leave no room for otiose discussions;
but even they feel obliged to justify their incuriosity. In easier
circumstances they, too, would claim the entirely human privilege of
'looking before and after,' as their forgotten progenitors may have
done. It is, indeed, difficult to think at all about the framework of
nature without attempting to divine, were it only by a crude surmise,
the process of its construction. We are instinctively convinced that
there is no such thing as fixity of condition. So far, Heracleitus was
in the right.
Experience tells us of continual change in ourselves and whatever
surrounds us. Reason teaches us that its minute momentary effects, if
pursued backward for an indefinite time, must sum up to a prodigious
total. No limit, that is to say, can be put to the difference
between what is and what was. Yet the machinery of modification
must somehow have been set going. An initial state is prescribed by
logical necessity. And the start was made on certain terms--it was
'conditioned.' But the conditioned implies the absolute; ordinances, an
enactive power. The inevitableness of the connection has been more or
less obscurely perceived wherever men have tried to establish some kind
of accord between phenomena and intuition, with results legible in the
wavering outlines of many primitive cosmogonies. Only, however, in the
Hebrew Scriptures has the idea of Creation been realized in all its
fulness and freedom; elsewhere the gods invoked to bring the world into
existence themselves demanded a birth-history, a theogony being the
usual and necessary prelude to a cosmogony.
Nevertheless 'picture-thoughts' (it has been well said),[1] and nothing
more, were represented by these prefatory genealogies. Night and
darkness loomed into personal shape, and from the obscurity of their
union the creatures of light radiantly sprang, and proceeded, according
to a predetermined law of order, to sort out the elements of chaos and
dispose them into cosmical harmony.
This mythical phase of thought terminated in Greece with the rise
of the Ionian School of Philosophy. Immemorial legends, discredited
by the advent of a new wisdom, took out a fresh lease of life under
the guise of folk-lore; Orphic fables were left to the poets and the
people; and the sage of Miletus set on foot a speculative tradition,
maintained by a long succession of metaphysicians down to the very
threshold of the recent scientific epoch. All were what we should call
evolutionists--Thales of Miletus no less than Descartes and Swedenborg;
their main object, in other words, was to find a practicable mode of
evoking a systematic arrangement of related parts from the monotony
of undifferentiated confusion. Now, in essaying this enterprise they
encountered two distinct problems. One was concerned with the nature
of the primeval world-stuff; the other with the operations to which it
had been submitted. Modern theorists have made it their primary object
to expound the mechanism of cosmic growth--the play of forces involved
in it, the transformations and progressive redistribution of energy
attending it. But questions of this kind could only in the scantiest
measure be formulated by early thinkers, who accordingly devoted their
chief attention to selecting an appropriate material for the exercise
of their constructive ingenuity.
Thales asserted all things to have been derived from water, and
water is still among unsophisticated tribes the favourite 'Urstoff.'
Anaximenes substituted air. Heracleitus gave the preference to the
mobile and vital element (as he thought it) of fire. Anaximander,
on the other hand, might put forward a colourable claim to priority
over Sir William Crookes in the invention of 'protyle.' He imagined
as the matrix of the world a boundless expanse of generalized matter,
containing potentially all the chemical species, which, separating out
by degrees through the affinity of like for like, formed, by their
contrasts and conjunctions, the infinitely varied sum of things.
The successors of Anaximander had recourse to spontaneously arising
condensations and rarefactions as the mainspring of development; but
all these vague principles were quickly crowded into oblivion by the
definite and intelligible doctrine of the 'four elements' enunciated
by Empedocles, which, guaranteed by the imprimatur of Plato, took a
place unchallenged for nearly two millenniums among the fundamentals
of science. Erroneous and misleading though it was, it yet served as
a means of regulating appearances and guiding vagrant ideas--it was a
track to follow in the absence of any better method of orientation.
Leucippus and his more famous disciples, Democritus and Epicurus, were
the first who ventured to trace the mechanical history of the cosmos.
Their primordial atoms were endowed with weight, and it was weight
or gravity which ultimately determined their spacial arrangement and
mutual relations. Rectilinear in the first draft of the scheme, their
movements were somewhat arbitrarily deflected by Epicurus; and the
gyrations thence ensuing eventually became, so to speak, authentic and
precise in the Cartesian vortices and in Swedenborg's solar maelstrom.
Kant's _Natural History_ of the universe was another, though an
entirely separate branch of the atomistic stock. The Democritean atoms,
however, and in a lesser degree the Kantian atoms, differed essentially
from the ultimates of chemical analysis postulated by Dalton. They were
a scratch lot--an incongruous assortment of fragments, rather than of
elementary portions of matter, indefinitely various in size, shape, and
mass.
Nor was this diversity created as a mere play of fancy. It was
strictly necessary to the plan of action adopted. For, apart from
heterogeneity, there could obviously be no development. Absolute
uniformity involves absolute permanence. Change can originate only
through inequality. There must be a tilt of level before the current
will begin to flow; some cause of predominance is needed to set it
going in a given direction. Here, of a surety, is the initial crux of
all cosmogonists. They usually surmount it by assuming the occurrence
of casual condensations, secure against disproof, while incapable of
verification. The expedient thus begs the question.
Theories of world-history made an integral part of antique philosophy.
Each founder of a school aimed at establishing a complete system of
knowledge, co-extensive with phenomena, embracing all things, from
the _primum mobile_ overhead to the blade of grass underfoot, and
rationalizing the past, present, and future of the comprehensive whole.
Modern science is less ambitious. Aspiring to no such vast synthesis,
it is content to make laborious acquaintance with the facts of nature,
to ponder their implications, and, if possible, to reconstruct on the
basis supplied by them the condition of things in the 'dim backward' of
unmeasured time. By no such means, it is true, can their beginning in
any real sense be arrived at; the weapons of induction become blunted
long before they strike home to the heart of that mystery; yet the
recognition of their inadequacy brings compensation in a fuller mastery
over their properly adapted use. Science, so called, was, indeed, down
to the Baconian era, a turbid mixture of physics with metaphysics. The
solution, it might be said, was attempted of an insoluble material
which refused to dissolve and was hindered from precipitating.
The Greek view of nature was essentially pantheistic. The Ionian
speculators appear to have presumed without expressly insisting upon
its self-regulating power. Aristotle alone emphatically rejected the
doctrine of cosmic vitality or sub-conscious tendencies. But Plato
accepted and magnified the Oriental tradition; the conception of a
'World-Soul' owed to him its vague splendour and perennial fascination.
The function of the Platonic vice-creator (for such the World-Soul
must be accounted) was that of moulding brute matter into conformity
with the archetypal ideas of the Divine mind; this was not, however,
accomplished once for all, but by a progressive spiritualizing of what
in its nature was dead and inanimate. The spiritual agent, becoming
incorporated with the universal frame, lent to it a semblance of life,
an obscure sensitiveness, and even some kind of latent intelligence;
and so the _anima mundi_ was shaped into existence, and continued
century by century to be the subject and source of imaginings beyond
measure wild and fantastic.
One great thought--that of the unity of nature--lay behind them, but
its significance was lost amid the phantasmagoria of Neo-Platonist
exaltations. Hence the Bacchic fervours of Giordano Bruno took their
inspiration; here was the groundwork of Spinoza's pantheism. Shelley's
Demiorgon, felt as 'a living spirit,' seen as 'a mighty darkness,'
descended lineally from that strange essence--formless, inarticulate,
devoid of individual self-consciousness--which animated the submerged
philosophy of Neo-Pagan times with the barren ardours of mysticism. The
doctrine, in its original and more sober version, obtained memorable
expression in Virgil's melodious hexameters:
'Principio cœlum, ac terras, camposque liquentes,
Lucentemque globum lunæ, Titaniaque astra,
Spiritus intus alit, totamque infusa per artus
Mens agitat molem, et magno se corpore miscet.'
In Conington's rhymed version they run as follows:
'Know first, the heaven, the earth, the main,
The moon's pale orb, the starry train,
Are nourished by a soul,
A bright intelligence, whose flame
Glows in each member of the frame,
And stirs the mighty whole.'
Kepler was no cosmogonist, but he aspired to found a 'physical
astronomy,' and in his gropings for a mechanical power that might
suffice to regulate the movements of the heavenly bodies, he stumbled
upon a mode of action highly appropriate for the explanation of their
growth. His ignorance of the laws of motion precluded him from the
conception of velocities persistent in themselves, and merely deflected
from straight into curved paths by a constant central pull. Hence he
was driven to the twofold expedient of creating a whirling medium for
maintaining the revolutions of the planets, and of supposing the sun
to exercise a 'magnetic influence,' by which they were drawn into
closed orbits. Here, then, central forces made a definitive entry on
the astronomical stage, although with scarcely a discernible promise
of their brilliant future. But it was otherwise with the clumsy
machinery they helped to animate. Kepler's simple _modus operandi_,
adopted, or more probably re-invented by Descartes, was published as
an epoch-making discovery in his _Principia Philosophica_ (1644), and
sprang under its new aspect into swift notoriety. The wide acceptance
of the theory of vortices was at least in part due to the impressive
largeness of its framework. Descartes left nothing out. The spacious
scope of his speculations embraced all that was knowable--nature,
animate and inanimate, life and time:
'Planets and the pale populace of heaven,
The mind of man, and all that's made to soar.'
A philosophy, a metaphysic, and a cosmogony were linked together in a
single plan. Its author distinguished in matter three gradations of
fineness. The coarsest kind was that composing the earth and other
opaque bodies; the more sublimated materials of the sun and stars
came next; finally, there was the ethereal substance of the skies, so
delicately constituted as to be luminous or luminiferous. This last
variety was regarded as of subordinate origin. It represented, in fact,
a kind of celestial detritus. Interstellar space had gradually become
filled with intangible dust, the product of molecular attrition among
originally angular solar and stellar particles. Ether was thus supposed
to bear to the subtlest description of ordinary matter very much the
same sort of relationship that ions presumably do to atoms.
Enough has been said to show that the Cartesian universe was based on
crude atomism. Its mode of construction, moreover, evinced a total
disregard of mechanical principles. Yet some acquaintance with the
laws of motion was by that time easily within reach. The first of the
three, at any rate, had been unmistakably enounced by Galileo in 1632,
and Descartes himself strongly championed its validity. Yet he thought
it necessary, in order to keep the planets moving, to immerse them in
one great self-gyrating vortex centred on the sun, each being further
provided with a similar subordinate whirlpool for the maintenance
of its domestic system. Comets were left in a singularly anomalous
position. They circulated freely on the whole, their exemption from
planetary restrictions being tacitly recognized; nevertheless, they
took advantage of every encountered swirl to help themselves on towards
their destination.
Among the fables of pseudo-science Delambre declared that, had the
choice been offered to him, he would have preferred the solid spheres
of Aristotle to the _tourbillons_ of Descartes. 'The spheres,'
he added,[2] 'have proved helpful both for the construction of
planetariums representing in a general way the celestial movements, and
for their calculation by approximate rules deduced from them; but the
system of vortices has never served any purpose whatsoever, whether
mechanical or computative.'
Its vogue had, nevertheless, been brilliant and sustained. Advanced
thinkers in the time of Louis Quatorze piqued themselves upon being
Cartesians. The vortical hypothesis was novel--it seemed daring; and
though it might not be true, it had plausibility enough for fashionable
currency. Nor did it deserve the unmitigated contempt with which it
was treated by Delambre. A glance at the skies makes us pause before
condemning it to scornful oblivion. Just two centuries after its
promulgation the first spiral nebula was identified in Canes Venatici.
That the heavens swarm with analogous objects is certain, and their
status as partially developed systems is visible in every line of their
conformation. Our own planetary world may, or may not, have traversed
the stage they so copiously illustrate; but in any case they prove
beyond question that vortices variously conditioned are prevalent
among the forms assumed by cosmic masses advancing towards an orderly
arrangement.
Mystical cosmogonies belong to the period of ethnic infancy. They
have not ceased to be current. World-fables must be invented wherever
the obscure wonder of savage communities is excited by the mysterious
spectacle of Nature's apparently designed operations and irresistible
power. But they were superseded among peoples in the van of progress
by philosophic cosmogonies at the epoch when Thales began to diffuse
throughout Ionia the wisdom of the Egyptians and Chaldeans. Schemes,
however, such as he and his successors elaborated result from the
discourse of reason unfettered by any close attention to facts.
They have been mostly wrought out by men who, in Delambre's words,
'Dissertaient à perte de vue, sans jamais rien observer, et sans jamais
rien calculer.'
The insubstantial fabrics reared by them were then fatally
discredited by Baconian methods and the Newtonian reign of law; they
survived--forms of thought die slowly--but insecurely, with noticeably
undermined foundations. Swedenborg was the last eminent reactionary,
and his restoration in 1734 of the Cartesian gyrating medium as the
motive power of the solar machine was a palpable failure. It could not
be otherwise, since its inceptive idea had grown superannuated. The
modern era of scientific cosmogony was at hand.
It was preceded by some remarkable attempts at sidereal generalization.
Cosmology is the elder sister of cosmogony. What _is_ must be studied
before what _was_ can be inferred. Precedent states remain visionary
unless they can be closely linked to actual and observable conditions.
Now about the middle of the eighteenth century an intelligible plan of
the stellar universe, so far as the telescope had then disclosed it,
began to be a desideratum. And the enterprise of supplying the need was
undertaken independently by two men of obscure origin and imperfect
education--one English, the other German.
Thomas Wright, of Durham, was the son of a carpenter at Byer's
Green, where he was born September 22, 1711. His life was one of
many vicissitudes, but ended happily. Having struggled hard for a
livelihood--now at sea, then again on shore as a clock and almanac
maker, a teacher and lecturer--he finally attained, somewhat
unaccountably, to distinction and affluence, built himself a handsome
house hard by his native shanty, and prosperously and reputably
inhabited it during a quarter of a century. He died February 25,
1786, just one year after Herschel had described to the Royal Society
the outcome of his first experiments in 'star gauging.' As the
originator of the 'cloven disc' theory of the Milky Way, Wright is
still deservedly remembered, for although that majestic structure is
assuredly otherwise designed, it was no mean achievement to have
initiated the science of its architecture.
Heinrich Lambert was a still more adventurous speculator than his
unknown English rival. His father was a poor tailor at Mühlhausen,
then in Swiss territory, and he worked as his apprentice. But his
irrepressible talents brought him into notice, and he died, in 1777,
through the favour of the second Frederick, a Berlin Academician. His
_Cosmological Letters_, published in 1761, were entirely original; they
were composed in ignorance of what Wright and Kant had already written.
In some respects he overtopped them both. He had splendid intuitions,
and just touched the confines of greatness. And if his performances
fell short of the very highest, it may have been rather through
abridgment of opportunity than through lack of capacity. The Milky Way
marked, to his apprehension, a sidereal ecliptic, and he coincided with
Wright in regarding it as a disc of aggregated stars, but with breaches
and gaps indicating a multiplicity of systems circulating, he thought,
round a common centre. Nor did he doubt the existence of other
Milky Ways--numberless, remote, unseen--grouped into a combination
of a higher order; while beyond, and still beyond, stretched further
hierarchies of systems on an ascending scale of magnitude and grandeur.
Our knowledge of the structural facts of the universe can never be made
exhaustive; in the middle of the eighteenth century, before Herschel
had opened his sidereal campaign, it was barely elementary. Wright
and Lambert were accordingly on a stint of material--they had to make
bricks with very little straw. Yet they did their best with what was
at hand. Both paid profound attention to the stellar heavens; they
earnestly sought the true interpretation of the appearances presented
by them, holding it possible, as we, despite accumulating difficulties,
still do, to harmonize countless detached phenomena in one vast
synthetic plan.
It was this purpose of fidelity to Nature which gave value to their
work, and made it a new thing in cosmological history. This alone
lent it impulsive force, and caused the meditations of two lonely
thinkers to become effective in stimulating fresh attempts, favoured
by improved conditions, to comprehend what actually exists, and to
infer thence, with rational confidence, its sources in the vague but
undeniable past.
FOOTNOTES:
[Footnote 1: Zeller, _History of Greek Philosophy_, translated by S.F.
Alleyne, vol. i., p. 86.]
[Footnote 2: Quoted by R. Wolf, _Handbuch der Astronomie_, Bd. II., p.
593.]