An illustration of Energy. The chemical energy brought into existence by
firing the explosive manifesting itself as mechanical energy, sufficient
to impart violent motion to tons of water.]
[Illustration: _Photo: Underwood & Underwood._
"BOILING" A KETTLE ON ICE
When a kettle containing liquid air is placed on ice it "boils" because
the ice is intensely hot _when compared with the very low temperature of
the liquid air_.]
If all the molecules of a substance were brought to a standstill, that
substance would be at the absolute zero of temperature. There could be
nothing colder. The temperature at which all molecular motions would
cease is known: it is -273° C. No body could possibly attain a lower
temperature than this: a lower temperature could not exist. Unless there
exists in nature some process, of which we know nothing at present,
whereby energy is renewed, our solar system must one day sink to this
absolute zero of temperature. The sun, the earth, and every other body
in the universe is steadily radiating heat, and this radiation cannot go
on for ever, because heat continually tends to diffuse and to equalise
temperatures.
But we can see, theoretically, that there is a way of evading this law.
If the chaotic molecular motions which constitute heat could be
_regulated_, then the heat energy of a body could be utilised directly.
Some authorities think that some of the processes which go on in the
living body do not involve any waste energy, that the chemical energy of
food is transformed directly into work without any of it being
dissipated as useless heat energy. It may be, therefore, that man will
finally discover some way of escape from the natural law that, while
energy cannot be destroyed, it has a tendency to become unavailable.
The primary reservoir of energy is the atom; it is the energy of the
atom, the atom of elements in the sun, the stars, the earth, from which
nature draws for all her supply of energy. Shall we ever discover how we
can replenish the dwindling resources of energy, or find out how we can
call into being the at present unavailable energy which is stored up in
uniform temperature?
It looks as if our successors would witness an interesting race,
between the progress of science on the one hand and the depletion of
natural resources upon the other. The natural rate of flow of energy
from its primary atomic reservoirs to the sea of waste heat energy
of uniform temperature, allows life to proceed at a complete pace
sternly regulated by the inexorable laws of supply and demand,
which the biologists have recognised in their field as the struggle
for existence.[5]
[5] _Matter and Energy_, by Professor Soddy.
It is certain that energy is an actual entity just as much as matter,
and that it cannot be created or destroyed. Matter and ether are
receptacles or vehicles of energy. As we have said, what these entities
really are in themselves we do not know. It may be that all forms of
energy are in some fundamental way aspects of the same primary entity
which constitutes matter: how all matter is constituted of particles of
electricity we have already seen. The question to which we await an
answer is: What is electricity?
§ 15