I
What has been regarded by many as the greatest scientific triumph of
modern times was worked out about the middle of the last century by
James Prescott Joule and others, in determining that a certain amount of
mechanical energy is exactly equivalent to a definite amount of heat.
With this mechanical equivalent of heat all the various other forms of
energy have also been correlated; until now we have the general law of
the Conservation of Energy, which says that energy can be neither
manufactured nor destroyed, but merely transformed and directed. And
this magnificent law, like that of the conservation of matter, is strong
evidence that there must have been a real Creation at some time in the
long ago, different not merely in degree but in kind from anything known
to modern science.
Joule worked out the mechanical equivalent of heat by means of his now
famous experiment of churning water. He reasoned that if the heat
produced by friction, etc., is really energy in another form, then the
same amount of heat must always be generated by the expenditure of a
given amount of motion or mechanical work. And this must be true, no
matter whether this work is expended in overcoming the friction between
wood on wood, iron on iron, or in any other conceivable way.
Accordingly, he devised an experiment in which paddle wheels were made
to rotate in a vessel of water by means of falling weights somewhat like
the weights of a clock. The amount of work represented by the falling of
the weights was easily calculated, and so was the amount of rise in
temperature of the water caused by the friction of the water with the
rotating paddle wheels. In various other ways he measured the amount of
heat generated by a measured amount of work; and as the result of all
his experiments (with very slight corrections made since by means of
more exact apparatus), we now know that 778 foot pounds of work produce
heat enough to raise one pound of water one degree Fahrenheit; or stated
in the metric system, 427 kilogram meters of work will produce a calorie
of heat.
Since these record-making experiments by Joule, the matter has been
verified over and over again in all sorts of ways; and almost every kind
of display of energy has been measured with more or less exactness. Even
the amount of food oxidized in the human body is now known to be capable
of correlation with the other forms of energy, though necessarily very
minute exactness of measurement is scarcely attainable in this case. But
no scientist of to-day doubts that all the physiological processes of
animals or of plants conform exactly to the law of the conservation of
energy that energy is neither created nor destroyed by any means known
to science. In other words, the amount of energy in our world, if
science can at all determine such a matter, seems to be _a fixed
quantity_, gradually being dissipated into space, it is true, but
momently replenished from the sun at exactly the same rate now as
hundreds or thousands of years ago. And while this energy is in our
world it is always capable of exact correlation in all of its
multitudinous forms, and is transformable back and forth without
increase and without loss.
On the discovery of the radioactive substances in 1896, some persons
hastily concluded that the law of the conservation of energy was
contradicted by the astonishing way in which these substances acted. But
further and more accurate experiments have set this matter at rest, as
indeed might have been expected; for the law of gravitation itself is
not more immovably established in the make-up of the universe than this
magnificent law that energy cannot be created by any means which we call
natural.
In all ages there have been men who have spent their lives in the vain
effort to invent a machine out of which work could constantly be
obtained without the expenditure upon it of an equal amount of work. But
the United States patent office has got so tired of receiving
applications for patents based on this idea of perpetual motion that
they have long since refused to issue any such patent where this
principle is the manifest object; and I suppose the governments of other
countries have taken a similar stand. And why? Because they know that
energy cannot now be created by any device, no matter how ingenious; and
they refuse to become a party to any scheme that seems to imply that
this modern creation of energy is within the bounds of possibility.
Yet what is all this but a confirmation of the declaration long ago made
that "the works were finished from the foundation of the world" (Heb.
4:3)? True, the energy we are constantly employing seems to come to us
from the sun; but we must remember that the sun and its family of the
solar system, including the earth, were all made at the same time, that
they are bound together as parts of an indissoluble whole. Accordingly,
no one can say that the total amount of energy called into existence at
the creation of our solar system is being added to at the present time.
At any rate, so far as modern science can judge of the matter, the total
amount of energy available for our world _is a fixed quantity_; and its
amount and the terms on which it was to be available for our use were
fixed or finished "from the foundation of the world." While it is a very
significant fact in this connection that with all the multiform
speculations which have been made as to the physical source of the sun's
heat, no explanation wholly satisfactory has yet been made as to how
this energy coming to us from the sun is constantly replenished or
maintained.