66 UNIVERSITY OF MISSOURI BULLETIN 



a condition of uniform temperature throughout the universe, 

 we will ultimately reach a state where it will be impossible 

 to convert any heat energy into mechanical work. Hence, 

 while the amount of energy in the universe remains constant 

 the amount available for use is steadily decreasing. This law 

 being cosmic in extent has attracted much attention from those 

 interested in such problems. 



While the principles of mechanics have been the dominant 

 ones in the bringing together of these various branches of 

 physics, there, have been other cases, for example, a certain 

 method and law originally developed for heat is now applied to 

 problems in optics, in electro-chemistry and other apparently 

 widely divergent cases. But the immense strides taken in 

 the last half century in the correlation of our different 

 branches are the direct result of the extended use of the 

 principles and methods of one of the branches to the whole 

 subject of physics. 



Each of these branches has its own particular laws. 

 But when we extend one branch to cover all, we do not 

 destroy these particular laws, but place as supreme the laws 

 of the one, — that is the laws of mechanics. And since the 

 laws of mechanics are the laws of force, of motion, and of 

 energy, we can now say that all forces and all motion and 

 all changes in energy are governed by these fundamental laws. 

 No longer are new and mysterious forces invented. Elec- 

 trical forces and magnetic forces are the same kind of forces, 

 — that is they produce the same changes in motion that 

 equal mechanical forces would. In other words, there is only 

 one kind of force, one kind of energy, obeying hut one set 

 of lazvs. 



We may say that what is really achieved is that com- 

 plicated physical processes are now explained in terms of 

 more familiar ones. Newton, in explaining why the moon, 

 instead of following a straight path, was pulled back towards 

 the earth and constrained to move around it, showed that the 



