Page:Popular Science Monthly Volume 77.djvu/461

Rh friend, they can not put you in jail on such a charge as that." "Yes, but they have," replied the prisoner.

When our physicist says that radium can not remain at a higher temperature than its surroundings and continue to radiate heat, as that would be contrary to the second law of thermodynamics, the answer is—yes, but it does.

When he says that it can not continue to radiate energy without receiving energy from some other body, as that would be contrary to the principle of the conservation of energy, the answer is—yes, but it does it.

When some one says that helium or carbon dioxide can not appear in sealed tubes which contained no trace of these substances to begin with, the answer is—yes, but they do.

Let us suppose that we have a mass of gun powder and that it is possible to, and we do, cause it to explode, one grain at a time, each grain firing its neighbor—as in the fuse of a fire cracker. The temperature of the mass of gunpowder will be higher than its surroundings and it will give off heat and other forms of energy, and continue to do so so long as the powder lasts. No one would think of calling this an exception to the law of the conservation of energy, or the second law of thermodynamics. The source of the energy is the atomic potential energy of the powder itself.

Let us suppose that we have a sphere with frictionless surface rotating at an enormous speed. Suppose that particles of matter are thrown off at frequent intervals. These particles, on account of their high speed, possess considerable energy. Thus the sphere continues to give off energy without receiving any, as long as any mass remains. The source of the energy is the kinetic energy stored in the sphere at the outset, of which energy we are conscious only when we have some method of detecting and slowing down the projected particles.

Thus the energy radiated by radium might be stored within the radium atom as potential energy and liberated by a sort of atomic—or sub-atomic explosion. Or it might be stored as kinetic energy—of revolving electrons and liberated gradually as these electrons escape from their orbits. It might be stored in both forms. In any case it is intraatomic energy because stored within the atom itself, and liberated only by atomic change—disintegration. In neither case would there be a violation of the principle of the conservation of energy or of the second law of thermodynamics. Sooner or later all the energy will have been radiated. The fact that the supply is destined to last so long is what appeals to us as wonderful. And so it is. The world is full of wonderful things to any one who pauses long enough to think.

In this paper I have endeavored to give a general notion of the trend of physical science rather than an enumeration and description of