Up to the point we have reached, then, we see what the new view of
Matter is. Every atom of matter, of whatever kind throughout the whole
universe, is built up of electrons in conjunction with a nucleus. From
the smallest atom of all--the atom of hydrogen--which consists of one
electron, rotating round a positively charged nucleus, to a heavy
complicated atom, such as the atom of gold, constituted of many
electrons and a complex nucleus, _we have only to do with positive and
negative units of electricity_. The electron and its nucleus are
particles of electricity. All Matter, therefore, is nothing but a
manifestation of electricity. The atoms of matter, as we saw, combine
and form molecules. Atoms and molecules are the bricks out of which
nature has built up everything; ourselves, the earth, the stars, the
whole universe.
But more than bricks are required to build a house. There are other
fundamental existences, such as the various forms of energy, which give
rise to several complex problems. And we have also to remember, that
there are more than eighty distinct elements, each with its own definite
type of atom. We shall deal with energy later. Meanwhile it remains to
be said that, although we have discovered a great deal about the
electron and the constitution of matter, and that while the physicists
of our own day seem to see a possibility of explaining positive and
negative electricity, the nature of them both is unknown. There exists
the theory that the particles of positive and negative electricity,
which make up the atoms of matter, are points or centres of disturbances
of some kind in a universal ether, and that all the various forms of
energy are, in some fundamental way, aspects of the same primary entity
which constitutes matter itself.
But the discovery of the property of radio-activity has raised many
other interesting questions, besides that which we have just dealt with.
In radio-active elements, such as uranium for example, the element is
breaking down; in what we call radio-activity we have a manifestation of
the spontaneous change of elements. What is really taking place is a
transmutation of one element into another, from a heavier to a lighter.
The element uranium spontaneously becomes radium, and radium passes
through a number of other stages until it, in turn, becomes lead. Each
descending element is of lighter atomic weight than its predecessor. The
changing process, of course, is a very slow one. It may be that all
matter is radio-active, or can be made so. This raises the question
whether all the matter in the universe may not undergo disintegration.
There is, however, another side of the question, which the discovery of
radio-activity has brought to light, and which has effected a revolution
in our views. We have seen that in radio-active substances the elements
are breaking down. Is there a process of building up at work? If the
more complicated atoms are breaking down into simpler forms, may there
not be a converse process--a building up from simpler elements to more
complicated elements? It is probably the case that both processes are at
work.
There are some eighty-odd chemical elements on the earth to-day: are
they all the outcome of an inorganic evolution, element giving rise to
element, going back and back to some primeval stuff from which they
were all originally derived infinitely long ago? Is there an evolution
in the inorganic world which may be going on, parallel to that of the
evolution of living things; or is organic evolution a continuation of
inorganic evolution? We have seen what evidence there is of this
inorganic evolution in the case of the stars. We cannot go deeply into
the matter here, nor has the time come for any direct statement that can
be based on the findings of modern investigation. Taking it altogether
the evidence is steadily accumulating, and there are authorities who
maintain that already the evidence of inorganic evolution is convincing
enough. The heavier atoms would appear to behave as though they were
evolved from the lighter. The more complex forms, it is supposed, have
_evolved_ from the simpler forms. Moseley's discovery, to which
reference has been made, points to the conclusion that the elements are
built up one from another.
§ 8