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The Story of Evolution

Joseph McCabe

CHAPTER II.  THE FOUNDATIONS OF THE UNIVERSE

To the mind of the vast majority of earlier observers the phrase
"foundations of the universe" would have suggested something
enormously massive and solid. From what we have already seen we
are prepared, on the contrary, to pass from the inconceivably
large to the inconceivably small. Our sun is, as far as our
present knowledge goes, one of modest dimensions. Arcturus and
Canopus must be thousands of times larger than it. Yet our sun is
320,000 times heavier than the earth, and the earth weighs some
6,000,000,000,000,000,000,000 tons. But it is only in resolving
these stupendous masses into their tiniest elements that we can
reach the ultimate realities, or foundations, of the whole.

Modern science rediscovered the atoms of Democritus, analysed the
universe into innumerable swarms of these tiny particles, and
then showed how the infinite variety of things could be built up
by their combinations. For this it was necessary to suppose that
the atoms were not all alike, but belonged to a large number of
different classes. From twenty-six letters of the alphabet we
could make millions of different words. From forty or fifty
different "elements" the chemist could construct the most varied
objects in nature, from the frame of a man to a landscape. But
improved methods of research led to the discovery of new
elements, and at last the chemist found that he had seventy or
eighty of these "ultimate realities," each having its own very
definite and very different characters. As it is the experience
of science to find unity underlying variety, this was profoundly
unsatisfactory, and the search began for the great unity which
underlay the atoms of matter. The difficulty of the search may be
illustrated by a few figures. Very delicate methods were invented
for calculating the size of the atoms. Laymen are apt to
smile--it is a very foolish smile--at these figures, but it is
enough to say that the independent and even more delicate methods
suggested by recent progress in physics have quite confirmed
them.

Take a cubic millimetre of hydrogen. As a millimetre is less than
1/25th of an inch, the reader must imagine a tiny bubble of gas
that would fit comfortably inside the letter "o" as it is printed
here. The various refined methods of the modern physicist show
that there are 40,000 billion molecules (each consisting of two
atoms of the gas) in this tiny bubble. It is a little universe,
repeating on an infinitesimal scale the numbers and energies of
the stellar universe. These molecules are not packed together,
moreover, but are separated from each other by spaces which are
enormous in proportion to the size of the atoms. Through these
empty spaces the atoms dash at an average speed of more than a
thousand miles an hour, each passing something like 6,000,000,000
of its neighbours in the course of every second. Yet this
particle of gas is a thinly populated world in comparison with a
particle of metal. Take a cubic centimetre of copper. In that
very small square of solid matter (each side of the cube
measuring a little more than a third of an inch) there are about
a quadrillion atoms. It is these minute and elusive particles
that modern physics sets out to master.

At first it was noticed that the atom of hydrogen was the
smallest or lightest of all, and the other atoms seemed to be
multiples of it. A Russian chemist, Mendeleeff, drew up a table
of the elements in illustration of this, grouping them in
families, which seemed to point to hydrogen as the common parent,
or ultimate constituent, of each. When newly discovered elements
fell fairly into place in this scheme the idea was somewhat
confidently advanced that the evolution of the elements was
discovered. Thus an atom of carbon seemed to be a group of 12
atoms of hydrogen, an atom of oxygen 16, an atom of sulphur 32,
an atom of copper 64, an atom of silver 108, an atom of gold 197,
and so on. But more correct measurements showed that these
figures were not quite exact, and the fraction of inexactness
killed the theory.

Long before the end of the nineteenth century students were
looking wistfully to the ether for some explanation of the
mystery. It was the veiled statue of Isis in the scientific
world, and it resolutely kept its veil in spite of all progress.
The "upper and limpid air" of the Greeks, the cosmic ocean of
Giordano Bruno, was now an established reality. It was the
vehicle that bore the terrific streams of energy from star to
planet across the immense reaches of space. As the atoms of
matter lay in it, one thought of the crystal forming in its
mother-lye, or the star forming in the nebula, and wondered
whether the atom was not in some such way condensed out of the
ether. By the last decade of the century the theory was
confidently advanced--notably by Lorentz and Larmor-- though it
was still without a positive basis. How the basis was found, in
the last decade of the nineteenth century, may be told very
briefly.

Sir William Crookes had in 1874 applied himself to the task of
creating something more nearly like a vacuum than the old
air-pumps afforded. When he had found the means of reducing the
quantity of gas in a tube until it was a million times thinner
than the atmosphere, he made the experiment of sending an
electric discharge through it, and found a very curious result.
From the cathode (the negative electric point) certain rays
proceeded which caused a green fluorescence on the glass of the
tube. Since the discharge did not consist of the atoms of the
gas, he concluded that it was a new and mysterious substance,
which he called "radiant matter." But no progress was made in the
interpretation of this strange material. The Crookes tube became
one of the toys of science--and the lamp of other investigators.

In 1895 Rontgen drew closer attention to the Crookes tube by
discovering the rays which he called X-rays, but which now bear
his name. They differ from ordinary light-waves in their length,
their irregularity, and especially their power to pass through
opaque bodies. A number of distinguished physicists now took up
the study of the effect of sending an electric discharge through
a vacuum, and the particles of "radiant matter" were soon
identified. Sir J. J. Thomson, especially, was brilliantly
successful in his interpretation. He proved that they were tiny
corpuscles, more than a thousand times smaller than the atom of
hydrogen, charged with negative electricity, and travelling at
the rate of thousands of miles a second. They were the
"electrons" in which modern physics sees the long-sought
constituents of the atom.

No sooner had interest been thoroughly aroused than it was
announced that a fresh discovery had opened a new shaft into the
underworld. Sir J. J. Thomson, pursuing his research, found in
1896 that compounds of uranium sent out rays that could penetrate
black paper and affect the photographic plate; though in this
case the French physicist, Becquerel, made the discovery
simultaneously' and was the first to publish it. An army of
investigators turned into the new field, and sought to penetrate
the deep abyss that had almost suddenly disclosed itself. The
quickening of astronomy by Galilei, or of zoology by Darwin, was
slight in comparison with the stirring of our physical world by
these increasing discoveries. And in 1898 M. and Mme. Curie made
the further discovery which, in the popular mind, obliterated all
the earlier achievements. They succeeded in isolating the new
element, radium, which exhibits the actual process of an atom
parting with its minute constituents.

The story of radium is so recent that a few lines will suffice to
recall as much as is needed for the purpose of this chapter. In
their study of the emanations from uranium compounds the Curies
were led to isolate the various elements of the compounds until
they discovered that the discharge was predominantly due to one
specific element, radium. Radium is itself probably a product of
the disintegration of uranium, the heaviest of known metals, with
an atomic weight some 240 times greater than that of hydrogen.
But this massive atom of uranium has a life that is computed in
thousands of millions of years. It is in radium and its offspring
that we see most clearly the constitution of matter.

A gramme (less than 15 1/2 grains) of radium contains-- we will
economise our space--4x10 (superscript)21 atoms. This tiny mass
is, by its discharge, parting with its substance at the rate of
one atom per second for every 10,000,000,000 atoms; in other
words, the "indestructible" atom has, in this case, a term of
life not exceeding 2500 years. In the discharge from the radium
three elements have been distinguished. The first consists of
atoms of the gas helium, which are hurled off at between 10,000
and 20,000 miles a second. The third element (in the order of
classification) consists of waves analogous to the Rontgen rays.
But the second element is a stream of electrons, which are
expelled from the atom at the appalling speed of about 100,000
miles a second. Professor Le Bon has calculated that it would
take 340,000 barrels of powder to discharge a bullet at that
speed. But we shall see more presently of the enormous energy
displayed within the little system of the atom. We may add that
after its first transformation the radium passes, much more
quickly, through a further series of changes. The frontiers of
the atomic systems were breaking down.

The next step was for students (notably Soddy and Rutherford) to
find that radio-activity, or spontaneous discharge out of the
atomic systems, was not confined to radium. Not only are other
rare metals conspicuously active, but it is found that such
familiar surfaces as damp cellars, rain, snow, etc., emit a
lesser discharge. The value of the new material thus provided for
the student of physics may be shown by one illustration. Sir J.
J. Thomson observes that before these recent discoveries the
investigator could not detect a gas unless about a billion
molecules of it were present, and it must be remembered that the
spectroscope had already gone far beyond ordinary chemical
analysis in detecting the presence of substances in minute
quantities. Since these discoveries we can recognise a single
molecule, bearing an electric charge.

With these extraordinary powers the physicist is able to
penetrate a world that lies immeasurably below the range of the
most powerful microscope, and introduce us to systems more
bewildering than those of the astronomer. We pass from a
portentous Brobdingnagia to a still more portentous Lilliputia.
It has been ascertained that the mass of the electron is the
1/1700th part of that of an atom of hydrogen, of which, as we
saw, billions of molecules have ample space to execute their
terrific movements within the limits of the letter "o." It has
been further shown that these electrons are identical, from
whatever source they are obtained. The physicist therefore
concludes-- warning us that on this further point he is drawing a
theoretical conclusion--that the atoms of ordinary matter are
made up of electrons. If that is the case, the hydrogen atom, the
lightest of all, must be a complex system of some 1700 electrons,
and as we ascend the scale of atomic weight the clusters grow
larger and larger, until we come to the atoms of the heavier
metals with more than 250,000 electrons in each atom.

But this is not the most surprising part of the discovery. Tiny
as the dimensions of the atom are, they afford a vast space for
the movement of these energetic little bodies. The speed of the
stars in their courses is slow compared with the flight of the
electrons. Since they fly out of the system, in the conditions we
have described, at a speed of between 90,000 and 100,000 miles a
second, they must be revolving with terrific rapidity within it.
Indeed, the most extraordinary discovery of all is that of the
energy imprisoned within these tiny systems, which men have for
ages regarded as "dead" matter. Sir J. J. Thomson calculates
that, allowing only one electron to each atom in a gramme of
hydrogen, the tiny globule of gas will contain as much energy as
would be obtained by burning thirty-five tons of coal. If, he
says, an appreciable fraction of the energy that is contained in
ordinary matter were to be set free, the earth would explode and
return to its primitive nebulous condition. Mr. Fournier d'Albe
tells us that the force with which electrons repel each other is
a quadrillion times greater than the force of gravitation that
brings atoms together; and that if two grammes of pure electrons
could be placed one centimetre apart they would repel each other
with a force equal to 320 quadrillion tons. The inexpert
imagination reels, but it must be remembered that the speed of
the electron is a measured quantity, and it is within the
resources of science to estimate the force necessary to project
it at that speed.*

* See Sir J. J. Thomson, "The Corpuscular Theory of Matter"
(1907) and--for a more elementary presentment--"Light Visible and
Invisible" (1911); and Mr. Fournier d'Albe, "The Electron Theory"
(2nd. ed., 1907).


Such are the discoveries of the last fifteen years and a few of
the mathematical deductions from them. We are not yet in a
position to say positively that the atoms are composed of
electrons, but it is clear that the experts are properly modest
in claiming only that this is highly probable. The atom seems to
be a little universe in which, in combination with positive
electricity (the nature of which is still extremely obscure),
from 1700 to 300,000 electrons revolve at a speed that reaches as
high as 100,000 miles a second. Instead of being crowded
together, however, in their minute system, each of them has, in
proportion to its size, as ample a space to move in as a single
speck of dust would have in a moderate-sized room (Thomson). This
theory not only meets all the facts that have been discovered in
an industrious decade of research, not only offers a splendid
prospect of introducing unity into the eighty-one different
elements of the chemist, but it opens out a still larger prospect
of bringing a common measure into the diverse forces of the
universe.

Light is already generally recognised as a rapid series of
electro-magnetic waves or pulses in ether. Magnetism becomes
intelligible as a condition of a body in which the electrons
revolve round the atom in nearly the same plane. The difference
between positive and negative electricity is at least partly
illuminated. An atom will repel an atom when its equilibrium is
disturbed by the approach of an additional electron; the
physicist even follows the movement of the added electron, and
describes it revolving 2200 billion times a second round the
atom, to escape being absorbed in it. The difference between good
and bad conductors of electricity becomes intelligible. The atoms
of metals are so close together that the roaming electrons pass
freely from one atom to another, in copper, it is calculated, the
electron combines with an atom and is liberated again a hundred
million times a second. Even chemical action enters the sphere of
explanation.

However these hypotheses may fare, the electron is a fact, and
the atom is very probably a more or less stable cluster of
electrons. But when we go further, and attempt to trace the
evolution of the electron out of ether, we enter a region of pure
theory. Some of the experts conceive the electron as a minute
whirlpool or vortex in the ocean of ether; some hold that it is a
centre of strain in ether; some regard ether as a densely packed
mass of infinitely small grains, and think that the positive and
negative corpuscles, as they seem to us, are tiny areas in which
the granules are unequally distributed. Each theory has its
difficulties. We do not know the origin of the electron, because
we do not know the nature of ether. To some it is an elastic
solid, quivering in waves at every movement of the particles; to
others it is a continuous fluid, every cubic millimetre of which
possesses "an energy equivalent to the output of a
million-horse-power station for 40.000,000 years" (Lodge); to
others it is a close-packed granular mass with a pressure of
10,000 tons per square centimetre. We must wait. It is little
over ten years since the vaults were opened and physicists began
to peer into the sub-material world. The lower, perhaps lowest,
depth is reserved for another generation.

But it may be said that the research of the last ten years has
given us a glimpse of the foundations of the universe. Every
theory of the electron assumes it to be some sort of nodule or
disturbed area in the ether. It is sometimes described as "a
particle of negative electricity" and associated with "a particle
of positive electricity" in building up the atom. The phrase is
misleading for those who regard electricity as a force or energy,
and it gives rise to speculation as to whether "matter" has not
been resolved into "force." Force or energy is not conceived by
physicists as a substantial reality, like matter, but an abstract
expression of certain relations of matter or electrons.

In any case, the ether, whether solid or fluid or granular,
remains the fundamental reality. The universe does not float IN
an ocean of ether: it IS an ocean of ether. But countless myriads
of minute disturbances are found in this ocean, and set it
quivering with the various pulses which we classify as forces or
energies. These points of disturbance cluster together in systems
(atoms) of from 1000 to 250,000 members, and the atoms are
pressed together until they come in the end to form massive
worlds. It remains only to reduce gravitation itself, which
brings the atoms together, to a strain or stress in ether, and we
have a superb unity. That has not yet been done, but every theory
of gravitation assumes that it is a stress in the ether
corresponding to the formation of the minute disturbances which
we call electrons.

But, it may be urged, he who speaks of foundations speaks of a
beginning of a structure; he who speaks of evolution must have a
starting-point. Was there a time when the ether was a smooth,
continuous fluid, without electrons or atoms, and did they
gradually appear in it, like crystals in the mother-lye? In
science we know nothing of a beginning. The question of the
eternity or non-eternity of matter (or ether) is as futile as the
question about its infinity or finiteness. We shall see in the
next chapter that science can trace the processes of nature back
for hundreds, if not thousands, of millions of years, and has
ground to think that the universe then presented much the same
aspect as it does now, and will in thousands of millions of years
to come. But if these periods were quadrillions, instead of
millions, of years, they would still have no relation to the idea
of eternity. All that we can say is that we find nothing in
nature that points to a beginning or an end.*

* A theory has been advanced by some physicists that there is
evidence of a beginning. WITHIN OUR EXPERIENCE energy is being
converted into heat more abundantly than heat is being converted
into other energy. This would hold out a prospect of a paralysed
universe, and that stage would have been reached long ago if the
system had not had a definite beginning. But what knowledge have
we of conversions of energy in remote regions of space, in the
depths of stars or nebulae, or in the sub-material world of which
we have just caught a glimpse? Roundly, none. The speculation is
worthless.


One point only need be mentioned in conclusion. Do we anywhere
perceive the evolution of the material elements out of electrons,
just as we perceive the devolution, or disintegration, of atoms
into electrons? There is good ground for thinking that we do. The
subject will be discussed more fully in the next chapter. In
brief, the spectroscope, which examines the light of distant
stars and discovers what chemical elements emitted it, finds
matter, in the hottest stars, in an unusual condition, and seems
to show the elements successively emerging from their fierce
alchemy. Sir J. Norman Lockyer has for many years conducted a
special investigation of the subject at the Solar Physics
Observatory, and he declares that we can trace the evolution of
the elements out of the fiery chaos of the young star. The
lightest gases emerge first, the metals later, and in a special
form. But here we pass once more from Lilliputia to
Brobdingnagia, and must first explain the making of the star
itself.
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