MODERN IDEAS AS TO MAN'S RELATION TO THE UNIVERSE
The beliefs as to the subordinate position held by sun, moon, and stars in
relation to the earth, which were almost universal down to the time of
Copernicus, began to give way when the discoveries of Kepler and the
revelations of the telescope demonstrated that our earth was not specially
distinguished from the other planets by any superiority of size or
position. The idea at once arose that the other planets might be inhabited;
and when the rapidly increasing power of the telescope, and of astronomical
instruments generally, revealed the wonders of the solar system and the
ever-increasing numbers of the fixed stars, the belief in other inhabited
worlds became as general as the opposite belief had been in all preceding
ages, and it is still held in modified forms to the present day.
But it may be truly said that the later like the earlier belief is founded
more upon religious ideas than upon a scientific and careful examination of
the whole of the facts both astronomical, physical, and biological, and we
must agree with the late Dr. Whewell, that the belief that other planets
are inhabited has been generally entertained, not in consequence of
physical reasons but in spite of them. And he adds:--'It was held that
Venus, or that Saturn was inhabited, not because anyone could devise, with
any degree of probability, any organised structure which would be suitable
to animal existence on the surfaces of those planets; but because it was
conceived that the greatness or goodness of the Creator, or His wisdom, or
some other of His attributes, would be manifestly imperfect, if these
planets were not tenanted by living creatures.' Those persons who have only
heard that many eminent astronomers down to our own day have upheld the
belief in a 'Plurality of Worlds' will naturally suppose that there must be
some very cogent arguments in its favour, and that it must be supported by
a considerable body of more or less conclusive facts. They will therefore
probably be surprised to hear that any direct evidence which may be held to
support the view is almost wholly wanting, and that the greater part of the
arguments are weak and flimsy in the extreme.
Of late years, it is true, some few writers have ventured to point out how
many difficulties there are in the way of accepting the belief, but even
these have never examined the question from the various points of view
which are essential to a proper consideration of it; while, so far as it is
still upheld, it is thought sufficient to show, that in the case of some of
the planets, there seem to be such conditions as to render life possible.
In the millions of planetary systems supposed to exist it is held to be
incredible that there are not great numbers as well fitted to be inhabited
by animals of all grades, including some as high as man or even higher,
and that we must, therefore, believe that they are so inhabited. As in the
present work I propose to show, that the probabilities and the weight of
direct evidence tend to an exactly opposite conclusion, it will be well to
pass briefly in review the various writers on the subject, and to give some
indication of the arguments they have used and the facts they have set
forth. For the earlier upholders of the theory I am indebted to Dr.
Whewell, who, in his _Dialogue on the Plurality of Worlds_--a Supplement to
his well-known volume on the subject--refers to all writers of importance
known to him.
The earliest are the great astronomers Kepler and Huygens, and the learned
Bishop Wilkins, who all believed that the moon was or might probably be
inhabited; and of these Whewell considers Wilkins to have been by far the
most thoughtful and earnest in supporting his views. Then we have Sir Isaac
Newton himself who, at considerable length, argued that the sun was
probably inhabited. But the first regular work devoted to the subject
appears to have been written by M. Fontenelle, Secretary to the Academy of
Sciences in Paris, who in 1686 published his _Conversations on the
Plurality of Worlds_. The book consisted of five chapters, the first
explaining the Copernican Theory; the second maintaining that the moon is a
habitable world; the third gives particulars as to the moon, and argues
that the other planets are also inhabited; the fourth gives details as to
the worlds of the five planets; while the fifth declares that the fixed
stars are suns, and that each illuminates a world. This work was so well
written, and the subject proved so attractive, that it was translated into
all the chief European languages, while the astronomer Lalande edited one
of the French editions. Three English translations were published, and one
of these went through six editions down to the year 1737. The influence of
this work was very great and no doubt led to that general acceptance of the
theory by such men as Sir William Herschel, Sir John Herschel, Dr.
Chalmers, Dr. Dick, Dr. Isaac Taylor, and M. Arago, although it was wholly
founded on pure speculation, and there was nothing that could be called
evidence on one side or the other.
This was the state of public opinion when an anonymous work appeared (in
1853) under the somewhat misleading title of _The Plurality of Worlds: An
Essay_. This was written, as already stated, by Dr. Whewell, who, for the
first time, ventured to doubt the generally accepted theory, and showed
that all the evidence at our command led to the conclusion that some of the
planets were _certainly_ not habitable, that others were _probably_ not so,
while in none was there that close correspondence with terrestrial
conditions which seemed essential for their habitability by the higher
animals or by man. The book was ably written and showed considerable
knowledge of the science of the time, but it was very diffuse, and the
larger part of it was devoted to showing that his views were not in any way
opposed to religion. One of his best arguments was founded on the
proposition that '_the Earth's Orbit is the Temperate Zone of the Solar
System_,' that there only is it possible to have those moderate variations
of heat and cold, dryness and moisture, which are suitable for animal
life. He suggested that the outer planets of the system consisted mainly of
water, gases, and vapour, as indicated by their low specific gravity, and
were therefore quite unsuitable for terrestrial life; while those near the
sun were equally unsuited, because, owing to the great amount of solar
heat, water could not exist on their surfaces. He devotes a great deal of
space to the evidence that there is no animal life on the moon, and taking
this as proved, he uses it as a counter argument against the other side.
They always urge that, the earth being inhabited, we must suppose the other
planets to be so too; to which he replies:--We know that the moon is not
inhabited though it has all the advantage of proximity to the sun that the
earth has; why then should not other planets be equally uninhabited?
He then comes to Mars and admits that this planet is very like the earth so
far as we can judge, and that it may therefore be inhabited, or as the
author expresses it, 'may have been judged worthy of inhabitants by its
Maker.' But he urges the small size of Mars, its coldness owing to distance
from the sun, and that the annual melting of its polar ice-caps will keep
it cold all through the summer. If there are animals they are probably of a
low type like the saurians and iguanodons of our seas during the Wealden
epoch; but, he argues, as even on our earth the long process of preparation
for man was carried on for countless millions of years, we need not discuss
whether there are intelligent beings on Mars till we have some better
evidence that there are any living creatures at all.
Several of the early chapters are devoted to an attempt to minimise the
difficulties of those religious persons who feel oppressed by the immensity
and complexity of the material universe as revealed by modern astronomy;
and by the almost infinite insignificance of man and his dwelling-place,
the earth, in comparison with it, an insignificance vastly increased if not
only the planets of the solar system, but also those which circle around
the myriads of suns, are also theatres of life. And these persons are
further disquieted because the very same facts are used by sceptics of
various kinds in their attacks upon Christianity. Such writers point out
the irrationality and absurdity of supposing that the Creator of all this
unimaginable vastness of suns and systems, filling for all we know endless
space, should take any _special_ interest in so mean and pitiful a creature
as man, the imperfectly developed inhabitant of one of the smaller worlds
attached to a second or third-rate sun, a being whose whole history is one
of war and bloodshed, of tyranny, torture, and death; whose awful record is
pictured by himself in such books as Josephus' _History of the Jews_, the
_Decline and Fall of the Roman Empire_, and even more forcibly summarised
in that terrible picture of human fiendishness and misery, _The Martyrdom
of Man_; while their character is indicated by one of the kindest and
simplest of their poets in the restrained but expressive lines:--
'Man's inhumanity to man
Makes countless thousands mourn.'
It is for such a being as this, they say, that God should have specially
revealed His will some thousands of years ago, and finding that His
commands were not obeyed, His will not fulfilled, yet ordained for their
benefit the necessarily unique sacrifice of His Son, in order to save a
small portion of these 'miserable sinners' from the natural and
well-deserved consequence of their stupendous follies, their unimaginable
crimes? Such a belief they maintain is too absurd, too incredible, to be
held by any rational being, and it becomes even less credible and less
rational if we maintain that there are countless other inhabited worlds.
It is very difficult for the religious man to make any adequate reply to
such an attack as this, and as a result many have felt their position to be
untenable and have accordingly lost all faith in the special dogmas of
orthodox Christianity. They feel themselves really to be between the horns
of a dilemma. If there are myriads of other worlds, it seems incredible
that they should each be the object of a special revelation and a special
sacrifice. If, on the other hand, we are the only intelligent beings that
exist in the material universe, and are really the highest creative product
of a Being of infinite wisdom and power, they cannot but wonder at the vast
apparent disproportion between the Creator and the created, and are
sometimes driven to Atheism from the hopelessness of comprehending so mean
and petty a result as the sole outcome of infinite power.
Whewell tells us that the great preacher, Dr. Chalmers, in his Astronomical
Discourses, attempted a reply to these difficulties, but, in his opinion,
not a very successful one; and a large part of his own work is devoted to
the same purpose. His main point seems to be that we know too little of the
universe to arrive at any definite conclusions on the question at issue,
and that any ideas that we may have as to the purposes of the Creator in
forming the vast system we see around us are almost sure to be erroneous.
We must therefore be content to remain ignorant, and must rest satisfied in
the belief that the Creator had a purpose although we are not yet permitted
to know what it was. And to those who urge that in other worlds there may
be other laws of nature which may render them quite as habitable by
intelligent beings as our world is for us, he replies, that if we are to
suppose new laws of nature in order to render each planet habitable, there
is an end of all rational inquiry on the subject, and we may maintain and
believe that animals may live on the moon without air or water, and on the
sun exposed to heat which vaporises earths and metals.
His concluding argument, and perhaps one of his strongest, is that founded
upon the dignity of man, as conferring a pre-eminence upon the planet which
has produced him. 'If,' he says, 'man be not merely capable of Virtue and
Duty, of universal Love and Self-Devotion, but be also immortal; if his
being be of infinite duration, his soul created never to die; then, indeed,
we may well say that one soul outweighs the whole unintelligent creation.'
And then, addressing the religious world, he urges that, if, as they
believe, God _has_ redeemed man by the sacrifice of His Son, and _has_
given to him a revelation of His will, then indeed no other conception is
possible than that he is the sole and highest product of the universe.
'The elevation of millions of intellectual, moral, religious, spiritual
creatures, to a destiny so prepared, consummated, and developed, is no
unworthy occupation of all the capacities of space, time, and matter.' Then
with a chapter on 'The Unity of the World,' and one on 'The Future,'
neither of which contains anything which adds to the force of his argument,
the book ends.
The publication of this able if rather vague and diffuse work, contesting
popular opinions, was followed by a burst of indignant criticism on the
part of a man of considerable eminence in some branches of physics--Sir
David Brewster, but who was very inferior, both in general knowledge of
science and in literary skill, to the writer whose views he opposed. The
purport of the book in which he set forth his objections is indicated by
its title--_More Worlds than One, the Creed of the Philosopher and the Hope
of the Christian_. Though written with much force and conviction it appeals
mainly to religious prejudices, and assumes throughout that every planet
and star is a special creation, and that the peculiarities of each were
designed for some special purpose. 'If,' he says, 'the moon had been
destined to be merely a lamp to our earth, there was no occasion to
variegate its surface with lofty mountains and extinct volcanoes, and cover
it with large patches of matter that reflect different quantities of light
and give its surface the appearance of continents and seas. It would have
been a better lamp had it been a smooth piece of lime or of chalk.' It is,
therefore, he thinks, prepared for inhabitants; and then he argues that all
the other satellites are also inhabited. Again he says that 'when it was
found that Venus was about the same size as the Earth, with mountains and
valleys, days and nights, and years analogous to our own, the _absurdity_
of believing that she had no inhabitants, when no other rational purpose
could be assigned for her creation, became an argument of a certain amount
that she was, like the Earth, the seat of animal and vegetable life.' Then,
when it was found that Jupiter was so gigantic 'as to require four moons to
give him light, the argument from analogy that _he_ was inhabited became
stronger also, because it extended to _two_ planets.' And thus each
successive planet having certain points of analogy with the others becomes
an additional argument; so that when we take account of all the planets,
with atmosphere, and clouds, and arctic snows, and trade-winds, the
argument from analogy becomes, he urges, very powerful;--'and the absurdity
of the opposite opinion, that planets should have moons and no inhabitants,
atmospheres with no creatures to breathe in them, and currents of air
without life to be fanned, became a formidable argument which few minds, if
any, could resist.'
The work is full of such weak and fallacious rhetoric and even, if
possible, still weaker. Thus after describing double stars, he adds--'But
no person can believe that two suns could be placed in the heavens for no
other purpose than to revolve round their common centre of gravity'; and he
concludes his chapter on the stars thus:--'Wherever there is matter there
must be Life; Life Physical to enjoy its beauties--Life Moral to worship
its Maker, and Life Intellectual to proclaim His wisdom and His power.' And
again--'A house without tenants, a city without citizens, presents to our
minds the same idea as a planet without life, and a universe without
inhabitants. Why the house was built, why the city was founded, why the
planet was made, and why the universe was created, it would be difficult
even to conjecture.' Arguments of this kind, which in almost every case beg
the question at issue, are repeated _ad nauseam_. But he also appeals to
the Old Testament to support his views, by quoting the fine passage in the
Psalms--'When I consider Thy heavens the work of Thy fingers, the moon and
the stars which Thou hast ordained; what is man that Thou art mindful of
him?' on which he remarks--'We cannot doubt that inspiration revealed to
him [David] the magnitude, the distances, and the final cause, of the
glorious spheres which fixed his admiration.' And after quoting various
other passages from the prophets, all as he thinks supporting the same
view, he sets forth the extraordinary idea as a confirmatory argument, that
the planets or some of them are to be the future abode of man. For, he
says--'Man in his future state of existence is to consist, as at present,
of a spiritual nature residing in a corporeal frame. He must live,
therefore, upon a material planet, subject to all the laws of matter.' And
he concludes thus:--'If there is not room, then, on our globe for the
millions of millions of beings who have lived and died on its surface, we
can scarcely doubt that their future abode must be on some of the primary
or secondary planets of the solar system, whose inhabitants have ceased to
exist, or upon planets which have long been in a state of preparation, as
our earth was, for the advent of intellectual life.'
It is pleasant to turn from such weak and trivial arguments to the only
other modern works which deal at some length with this subject, the late
Richard A. Proctor's _Other Worlds than Ours_, and a volume published five
years later under the title--_Our Place Among Infinities_. Written as these
were by one of the most accomplished astronomers of his day, remarkable
alike for the acuteness of his reasoning and the clearness of his style, we
are always interested and instructed even when we cannot agree with his
conclusions. In the first work mentioned above, he assumes, like Sir David
Brewster, the antecedent probability that the planets are inhabited and on
much the same theological grounds. So strongly does he feel this that he
continually speaks as if the planets _must_ be inhabited unless we can show
very good reason that they _cannot_ be so, thus throwing the burden of
proving a negative on his opponents, while he does not attempt to prove his
positive contention that they are inhabited, except by purely hypothetical
considerations as to the Creator's purpose in bringing them into existence.
But starting from this point he endeavours to show how Whewell's various
difficulties may be overcome, and here he always appeals to astronomical or
physical facts, and reasons well upon them. But he is quite honest; and,
coming to the conclusion that Jupiter and Saturn, Uranus and Neptune,
cannot be habitable, he adduces the evidence and plainly states the result.
But then he thinks that the satellites of Jupiter and Saturn _may_ be
habitable, and if they may be, then he concludes that they _must_. One
great oversight in his whole argument is, that he is satisfied with showing
the possibility that life may exist now, but never deals with the question
of whether life could have been developed from its earliest rudiments up to
the production of the higher vertebrates and man; and this, as I shall show
later, is the _crux_ of the whole problem.
With regard to the other planets, after a careful examination of all that
is known about them, he arrives at the conclusion that if Mercury is
protected by a cloud-laden atmosphere of a peculiar kind it may possibly,
but not probably, support high forms of animal life. But in the case of
Venus and Mars he finds so much resemblance to and so many analogies with
our earth, that he concludes that they almost certainly are so.
In the case of the fixed stars, now that we know by spectroscopic
observations that they are true suns, many of which closely resemble our
sun and give out light and heat as he does, Mr. Proctor argues, that 'The
vast supplies of heat thus emitted by the stars not only suggest the
conclusion that there must be worlds around these orbs for which these
heat-supplies are intended, but point to the existence of the various forms
of force into which heat may be transmuted. We know that the sun's heat
poured upon our earth is stored up in vegetable and animal forms of life;
is present in all the phenomena of nature--in winds and clouds and rain, in
thunder and lightning, storm and hail; and that even the works of man are
performed by virtue of the solar heat-supplies. Thus the fact that the
stars send forth heat to the worlds which circle around them suggests at
once the thought that on those worlds there must exist animal and vegetable
forms of life.' We may note that in the first part of this passage the
presence of worlds or planets is 'suggested,' while later on 'the worlds
which circle round them' is spoken of as if it were a proved fact from
which the presence of vegetable and animal life may be inferred. A
suggestion depending on a preceding suggestion is not a very firm basis for
so vast and wide-reaching a conclusion.
In the second work referred to above there is one chapter entitled, 'A New
Theory of Life in other Worlds,' where the author gives his more matured
views of the question, which are briefly stated in the preface as being
'that the weight of evidence favours my theory of the (relative) paucity of
worlds.' His views are largely founded on the theory of probabilities, of
which subject he had made a special study. Taking first our earth, he shows
that the period during which life has existed upon it is very small in
comparison with that during which it must have been slowly forming and
cooling, and its atmosphere condensing so as to form land and water on its
surface. And if we consider the time the earth has been occupied by man,
that is a very minute part, perhaps not the thousandth part, of the period
during which it has existed as a planet. It follows that even if we
consider only those planets whose physical condition seems to us to be such
as to be able to sustain life, the chances are perhaps hundreds to one
against their being at that particular stage when life has begun to be
developed, or if it has begun has reached as high a development as on our
earth.
With regard to the stars, the argument is still stronger, because the
epochs required for their formation are altogether unknown, while as to the
conditions required for the formation of planetary systems around them we
are totally ignorant. To this I would add that we are equally ignorant as
to the probability or even possibility of many of these suns producing
planets which, by their position, size, atmosphere, or other physical
conditions can possibly become life-producing worlds. And, as we shall see
later, this point has been overlooked by all writers, including Mr. Proctor
himself. His conclusion is, then, that although the worlds which possess
life at all approaching that of our earth may be relatively few in number,
yet considering the universe as practically infinite in extent, they may be
really very numerous.
It has been necessary to give this sketch of the views of those who have
written specially on the question of the Plurality of Worlds, because the
works referred to have been very widely read and have influenced educated
opinion throughout the world. Moreover, Mr. Proctor, in his last work on
the subject, speaks of the theory as being 'identified with modern
astronomy'; and in fact popular works still discuss it. But all these
follow the same general line of argument as those already referred to, and
the curious thing is that while overlooking many of the most essential
conditions they often introduce others which are by no means essential--as,
for instance, that the atmosphere must have the same proportion of oxygen
as our own. They seem to think that if any of our quadrupeds or birds taken
to another planet could not live there, no animals of equally high
organisation could inhabit it; entirely overlooking the very obvious fact
that, supposing, as is almost certain, that oxygen is necessary for life,
then, whatever proportion of oxygen within certain limits was present, the
forms of life that arose would necessarily be organised in adaptation to
that proportion, which might be considerably less or greater than on the
earth.
The present volume will show how extremely inadequate has been the
treatment of this question, which involves a variety of important
considerations hitherto altogether overlooked. These are extremely numerous
and very varied in their character, and the fact that they all point to one
conclusion--a conclusion which so far as I am aware no previous writer has
reached--renders it at least worthy of the careful consideration of all
unbiassed thinkers. The whole subject is one as to which no direct evidence
is obtainable, but I venture to think that the convergence of so many
probabilities and indications towards a single definite theory, intimately
connected with the nature and destiny of man himself, raises this theory to
a very much higher level of probability than the vague possibilities and
theological suggestions which are the utmost that have been adduced by
previous writers.
In order to make every step of my argument clearly intelligible to all
educated readers, it will be necessary to refer continually to the
marvellous extension of our knowledge of the universe obtained during the
last half-century, and constituting what is termed the New Astronomy. The
next chapter will therefore be devoted to a popular exposition of the new
methods of research, so that the results reached, which will have to be
referred to in succeeding chapters, may be not only accepted, but clearly
understood.