establishment of this great university in the very focus of the
commercial activity of the West. Its connection with the institution we
have been dedicating suggests some thoughts on science as a factor in
that scheme of education best adapted to make the power of a wealthy
community a benefit to the race at large. When we see what a factor
science has been in our present civilization, how it has transformed
the world and increased the means of human enjoyment by enabling men to
apply the powers of nature to their own uses, it is not wonderful that
it should claim the place in education hitherto held by classical
studies. In the contest which has thus arisen I take no part but that
of a peace-maker, holding that it is as important to us to keep in
touch with the traditions of our race, and to cherish the thoughts
which have come down to us through the centuries, as it is to enjoy and
utilize what the present has to offer us. Speaking from this point of
view, I would point out the error of making the utilitarian
applications of knowledge the main object in its pursuit. It is an
historic fact that abstract science--science pursued without any
utilitarian end--has been at the base of our progress in the
utilization of knowledge. If in the last century such men as Galvani
and Volta had been moved by any other motive than love of penetrating
the secrets of nature they would never have pursued the seemingly
useless experiments they did, and the foundation of electrical science
would not have been laid. Our present applications of electricity did
not become possible until Ohm's mathematical laws of the electric
current, which when first made known seemed little more than
mathematical curiosities, had become the common property of inventors.
Professional pride on the part of our own Henry led him, after making
the discoveries which rendered the telegraph possible, to go no further
in their application, and to live and die without receiving a dollar of
the millions which the country has won through his agency.
In the spirit of scientific progress thus shown we have patriotism in
its highest form--a sentiment which does not seek to benefit the
country at the expense of the world, but to benefit the world by means
of one's country. Science has its competition, as keen as that which is
the life of commerce. But its rivalries are over the question who shall
contribute the most and the best to the sum total of knowledge; who
shall give the most, not who shall take the most. Its animating spirit
is love of truth. Its pride is to do the greatest good to the greatest
number. It embraces not only the whole human race but all nature in its
scope. The public spirit of which this city is the focus has made the
desert blossom as the rose, and benefited humanity by the diffusion of
the material products of the earth. Should you ask me how it is in the
future to use its influence for the benefit of humanity at large, I
would say, look at the work now going on in these precincts, and study
its spirit. Here are the agencies which will make "the voice of law the
harmony of the world." Here is the love of country blended with love of
the race. Here the love of knowledge is as unconfined as your
commercial enterprise. Let not your youth come hither merely to learn
the forms of vertebrates and the properties of oxides, but rather to
imbibe that catholic spirit which, animating their growing energies,
shall make the power they are to wield an agent of beneficence to all
mankind.
XIX
THE UNIVERSE AS AN ORGANISM
[Footnote: Address before the Astronomical and Astrophysical Society of
America, December 29, 1902]
If I were called upon to convey, within the compass of a single
sentence, an idea of the trend of recent astronomical and physical
science, I should say that it was in the direction of showing the
universe to be a connected whole. The farther we advance in knowledge,
the clearer it becomes that the bodies which are scattered through the
celestial spaces are not completely independent existences, but have,
with all their infinite diversity, many attributes in common.
In this we are going in the direction of certain ideas of the ancients
which modern discovery long seemed to have contradicted. In the infancy
of the race, the idea that the heavens were simply an enlarged and
diversified earth, peopled by beings who could roam at pleasure from
one extreme to the other, was a quite natural one. The crystalline
sphere or spheres which contained all formed a combination of machinery
revolving on a single plan. But all bonds of unity between the stars
began to be weakened when Copernicus showed that there were no spheres,
that the planets were isolated bodies, and that the stars were vastly
more distant than the planets. As discovery went on and our conceptions
of the universe were enlarged, it was found that the system of the
fixed stars was made up of bodies so vastly distant and so completely
isolated that it was difficult to conceive of them as standing in any
definable relation to one another. It is true that they all emitted
light, else we could not see them, and the theory of gravitation, if
extended to such distances, a fact not then proved, showed that they
acted on one another by their mutual gravitation. But this was all.
Leaving out light and gravitation, the universe was still, in the time
of Herschel, composed of bodies which, for the most part, could not
stand in any known relation one to the other.
When, forty years ago, the spectroscope was applied to analyze the
light coming from the stars, a field was opened not less fruitful than
that which the telescope made known to Galileo. The first conclusion
reached was that the sun was composed almost entirely of the same
elements that existed upon the earth. Yet, as the bodies of our solar
system were evidently closely related, this was not remarkable. But
very soon the same conclusion was, to a limited extent, extended to the
fixed stars in general. Such elements as iron, hydrogen, and calcium
were found not to belong merely to our earth, but to form important
constituents of the whole universe. We can conceive of no reason why,
out of the infinite number of combinations which might make up a
spectrum, there should not be a separate kind of matter for each
combination. So far as we know, the elements might merge into one
another by insensible gradations. It is, therefore, a remarkable and
suggestive fact when we find that the elements which make up bodies so
widely separate that we can hardly imagine them having anything in
common, should be so much the same.
In recent times what we may regard as a new branch of astronomical
science is being developed, showing a tendency towards unity of
structure throughout the whole domain of the stars. This is what we now
call the science of stellar statistics. The very conception of such a
science might almost appall us by its immensity. The widest statistical
field in other branches of research is that occupied by sociology.
Every country has its census, in which the individual inhabitants are
classified on the largest scale and the combination of these statistics
for different countries may be said to include all the interest of the
human race within its scope. Yet this field is necessarily confined to
the surface of our planet. In the field of stellar statistics millions
of stars are classified as if each taken individually were of no more
weight in the scale than a single inhabitant of China in the scale of
the sociologist. And yet the most insignificant of these suns may, for
aught we know, have planets revolving around it, the interests of whose
inhabitants cover as wide a range as ours do upon our own globe.
The statistics of the stars may be said to have commenced with
Herschel's gauges of the heavens, which were continued from time to
time by various observers, never, however, on the largest scale. The
subject was first opened out into an illimitable field of research
through a paper presented by Kapteyn to the Amsterdam Academy of
Sciences in 1893. The capital results of this paper were that different
regions of space contain different kinds of stars and, more especially,
that the stars of the Milky Way belong, in part at least, to a
different class from those existing elsewhere. Stars not belonging to
the Milky Way are, in large part, of a distinctly different class.
The outcome of Kapteyn's conclusions is that we are able to describe
the universe as a single object, with some characters of an organized
whole. A large part of the stars which compose it may be considered as
divisible into two groups. One of these comprises the stars composing
the great girdle of the Milky Way. These are distinguished from the
others by being bluer in color, generally greater in absolute
brilliancy, and affected, there is some reason to believe, with rather
slower proper motions The other classes are stars with a greater or
less shade of yellow in their color, scattered through a spherical
space of unknown dimensions, but concentric with the Milky Way. Thus a
sphere with a girdle passing around it forms the nearest approach to a
conception of the universe which we can reach to-day. The number of
stars in the girdle is much greater than that in the sphere.
The feature of the universe which should therefore command our
attention is the arrangement of a large part of the stars which compose
it in a ring, seemingly alike in all its parts, so far as general
features are concerned. So far as research has yet gone, we are not
able to say decisively that one region of this ring differs essentially
from another. It may, therefore, be regarded as forming a structure
built on a uniform plan throughout.
All scientific conclusions drawn from statistical data require a
critical investigation of the basis on which they rest. If we are
going, from merely counting the stars, observing their magnitudes and
determining their proper motions, to draw conclusions as to the
structure of the universe in space, the question may arise how we can
form any estimate whatever of the possible distance of the stars, a
conclusion as to which must be the very first step we take. We can
hardly say that the parallaxes of more than one hundred stars have been
measured with any approach to certainty. The individuals of this one
hundred are situated at very different distances from us. We hope, by
long and repeated observations, to make a fairly approximate
determination of the parallaxes of all the stars whose distance is less
than twenty times that of a Centauri. But how can we know anything
about the distance of stars outside this sphere? What can we say
against the view of Kepler that the space around our sun is very much
thinner in stars than it is at a greater distance; in fact, that, the
great mass of the stars may be situated between the surfaces of two
concentrated spheres not very different in radius. May not this
universe of stars be somewhat in the nature of a hollow sphere?
This objection requires very careful consideration on the part of all
who draw conclusions as to the distribution of stars in space and as to
the extent of the visible universe. The steps to a conclusion on the
subject are briefly these: First, we have a general conclusion, the
basis of which I have already set forth, that, to use a loose
expression, there are likenesses throughout the whole diameter of the
universe. There is, therefore, no reason to suppose that the region in
which our system is situated differs in any essential degree from any
other region near the central portion. Again, spectroscopic
examinations seem to show that all the stars are in motion, and that we
cannot say that those in one part of the universe move more rapidly
than those in another. This result is of the greatest value for our
purpose, because, when we consider only the apparent motions, as
ordinarily observed, these are necessarily dependent upon the distance
of the star. We cannot, therefore, infer the actual speed of a star
from ordinary observations until we know its distance. But the results
of spectroscopic measurements of radial velocity are independent of the
distance of the star.
But let us not claim too much. We cannot yet say with certainty that
the stars which form the agglomerations of the Milky Way have, beyond
doubt, the same average motion as the stars in other regions of the
universe. The difficulty is that these stars appear to us so faint
individually, that the investigation of their spectra is still beyond
the powers of our instruments. But the extraordinary feat performed at
the Lick Observatory of measuring the radial motion of 1830
Groombridge, a star quite invisible to the naked eye, and showing that
it is approaching our system with a speed of between fifty and sixty
miles a second, may lead us to hope for a speedy solution of this
question. But we need not await this result in order to reach very
probable conclusions. The general outcome of researches on proper
motions tends to strengthen the conclusions that the Keplerian sphere,
if I may use this expression, has no very well marked existence. The
laws of stellar velocity and the statistics of proper motions, while
giving some color to the view that the space in which we are situated
is thinner in stars than elsewhere, yet show that, as a general rule,
there are no great agglomerations of stars elsewhere than in the region
of the Milky Way.
With unity there is always diversity; in fact, the unity of the
universe on which I have been insisting consists in part of diversity.
It is very curious that, among the many thousands of stars which have
been spectroscopically examined, no two are known to have absolutely
the same physical constitution. It is true that there are a great many
resemblances. Alpha Centauri, our nearest neighbor, if we can use such
a word as "near" in speaking of its distance, has a spectrum very like
that of our sun, and so has Capella. But even in these cases careful
examination shows differences. These differences arise from variety in
the combinations and temperature of the substances of which the star is
made up. Quite likely also, elements not known on the earth may exist
on the stars, but this is a point on which we cannot yet speak with
certainty.
Perhaps the attribute in which the stars show the greatest variety is
that of absolute luminosity. One hundred years ago it was naturally
supposed that the brighter stars were the nearest to us, and this is
doubtless true when we take the general average. But it was soon found
that we cannot conclude that because a star is bright, therefore it is
near. The most striking example of this is afforded by the absence of
measurable parallaxes in the two bright stars, Canopus and Rigel,
showing that these stars, though of the first magnitude, are
immeasurably distant. A remarkable fact is that these conclusions
coincide with that which we draw from the minuteness of the proper
motions. Rigel has no motion that has certainly been shown by more than
a century of observation, and it is not certain that Canopus has
either. From this alone we may conclude, with a high degree of
probability, that the distance of each is immeasurably great. We may
say with certainty that the brightness of each is thousands of times
that of the sun, and with a high degree of probability that it is
hundreds of thousands of times. On the other hand, there are stars
comparatively near us of which the light is not the hundredth part of
the sun.
[Illustration with caption: Star Spectra]
The universe may be a unit in two ways. One is that unity of structure
to which our attention has just been directed. This might subsist
forever without one body influencing another. The other form of unity
leads us to view the universe as an organism. It is such by mutual
action going on between its bodies. A few years ago we could hardly
suppose or imagine that any other agents than gravitation and light
could possibly pass through spaces so immense as those which separate
the stars.
The most remarkable and hopeful characteristic of the unity of the
universe is the evidence which is being gathered that there are other
agencies whose exact nature is yet unknown to us, but which do pass
from one heavenly body to another. The best established example of this
yet obtained is afforded in the case of the sun and the earth.
The fact that the frequency of magnetic storms goes through a period of
about eleven years, and is proportional to the frequency of sun-spots,
has been well established. The recent work of Professor Bigelow shows
the coincidence to be of remarkable exactness, the curves of the two
phenomena being practically coincident so far as their general features
are concerned. The conclusion is that spots on the sun and magnetic
storms are due to the same cause. This cause cannot be any change in
the ordinary radiation of the sun, because the best records of
temperature show that, to whatever variations the sun's radiation may
be subjected, they do not change in the period of the sun-spots. To
appreciate the relation, we must recall that the researches of Hale
with the spectro-heliograph show that spots are not the primary
phenomenon of solar activity, but are simply the outcome of processes
going on constantly in the sun which result in spots only in special
regions and on special occasions. It does not, therefore, necessarily
follow that a spot does cause a magnetic storm. What we should conclude
is that the solar activity which produces a spot also produces the
magnetic storm.
When we inquire into the possible nature of these relations between
solar activity and terrestrial magnetism, we find ourselves so
completely in the dark that the question of what is really proved by
the coincidence may arise. Perhaps the most obvious explanation of
fluctuations in the earth's magnetic field to be inquired into would be
based on the hypothesis that the space through which the earth is
moving is in itself a varying magnetic field of vast extent. This
explanation is tested by inquiring whether the fluctuations in question
can be explained by supposing a disturbing force which acts
substantially in the same direction all over the globe. But a very
obvious test shows that this explanation is untenable. Were it the
correct one, the intensity of the force in some regions of the earth
would be diminished and in regions where the needle pointed in the
opposite direction would be increased in exactly the same degree. But
there is no relation traceable either in any of the regular
fluctuations of the magnetic force, or in those irregular ones which
occur during a magnetic storm. If the horizontal force is increased in
one part of the earth, it is very apt to show a simultaneous increase
the world over, regardless of the direction in which the needle may
point in various localities. It is hardly necessary to add that none of
the fluctuations in terrestrial magnetism can be explained on the
hypothesis that either the moon or the sun acts as a magnet. In such a
case the action would be substantially in the same direction at the
same moment the world over.
Such being the case, the question may arise whether the action
producing a magnetic storm comes from the sun at all, and whether the
fluctuations in the sun's activity, and in the earth's magnetic field
may not be due to some cause external to both. All we can say in reply
to this is that every effort to find such a cause has failed and that
it is hardly possible to imagine any cause producing such an effect. It
is true that the solar spots were, not many years ago, supposed to be
due in some way to the action of the planets. But, for reasons which it
would be tedious to go into at present, we may fairly regard this
hypothesis as being completely disproved. There can, I conclude, be
little doubt that the eleven-year cycle of change in the solar spots is
due to a cycle going on in the sun itself. Such being the case, the
corresponding change in the earth's magnetism must be due to the same
cause.
We may, therefore, regard it as a fact sufficiently established to
merit further investigation that there does emanate from the sun, in an
irregular way, some agency adequate to produce a measurable effect on
the magnetic needle. We must regard it as a singular fact that no
observations yet made give us the slightest indication as to what this
emanation is. The possibility of defining it is suggested by the
discovery within the past few years, that under certain conditions,
heated matter sends forth entities known as Rontgen rays, Becquerel
corpuscles and electrons. I cannot speak authoritatively on this
subject, but, so far as I am aware, no direct evidence has yet been
gathered showing that any of these entities reach us from the sun. We
must regard the search for the unknown agency so fully proved as among
the most important tasks of the astronomical physicist of the present
time. From what we know of the history of scientific discovery, it
seems highly probable that, in the course of his search, he will,
before he finds the object he is aiming at, discover many other things
of equal or greater importance of which he had, at the outset, no
conception.
The main point I desire to bring out in this review is the tendency
which it shows towards unification in physical research. Heretofore
differentiation--the subdivision of workers into a continually
increasing number of groups of specialists--has been the rule. Now we
see a coming together of what, at first sight, seem the most widely
separated spheres of activity. What two branches could be more widely
separated than that of stellar statistics, embracing the whole universe
within its scope, and the study of these newly discovered emanations,
the product of our laboratories, which seem to show the existence of
corpuscles smaller than the atoms of matter? And yet, the phenomena
which we have reviewed, especially the relation of terrestrial
magnetism to the solar activity, and the formation of nebulous masses
around the new stars, can be accounted for only by emanations or forms
of force, having probably some similarity with the corpuscles,
electrons, and rays which we are now producing in our laboratories. The
nineteenth century, in passing away, points with pride to what it has
done. It has become a word to symbolize what is most important in human
progress Yet, perhaps its greatest glory may prove to be that the last
thing it did was to lay a foundation for the physical science of the
twentieth century. What shall be discovered in the new fields is, at
present, as far without our ken as were the modern developments of
electricity without the ken of the investigators of one hundred years
ago. We cannot guarantee any special discovery. What lies before us is
an illimitable field, the existence of which was scarcely suspected ten
years ago, the exploration of which may well absorb the activities of
our physical laboratories, and of the great mass of our astronomical
observers and investigators for as many generations as were required to
bring electrical science to its present state. We of the older
generation cannot hope to see more than the beginning of this
development, and can only tender our best wishes and most hearty
congratulations to the younger school whose function it will be to
explore the limitless field now before it.
XX
THE RELATION OF SCIENTIFIC METHOD TO SOCIAL PROGRESS [Footnote: An
address before the Washington Philosophical Society]