The mechanical engineering field is one of the oldest of the several engineering fields. It is also one of the broadest in scope, for it is not identified with nor restricted to any particular technology (like nuclear engineering), nor to any particular vehicle (like land-based automobiles), nor to any particular device or particular system.
It is, in fact, concerned with so many areas of modem technology that the tasks and challenges of the mechanical engineer are most interesting and varied.
The field is logically associated with mechanical things, but this can lead to a restrictive image. For example, one often associates mechanical engineers with automobiles and, thus, with engines. To the non-engineer this is an acceptable association that implies a knowledge of pistons and carburetors. As engineers know, this picture is very shallow; the breadth of understanding implied when one thinks of designing an engine challenges the imagination. Automobile engines are just one of many devices that convert energy into useful work.
To understand this conversion process is also to understand the basic principles of energy conversion applicable to solar engines, jet engines, gas turbines, fuel cells, ship-propulsion systems, rocket engines, hydro-electric power plants, and new kinds of converters not yet developed. The mechanical engineer possesses this universally applicable background in thermodynamics, heat transfer, fluid mechanics, aerodynamics, and combustion theory which is basic to all such systems. The mechanical engineer also has a similar understanding of materials from steels to textiles to biological materials to the latest plastics and the most exotic high temperature composites.
The point is that everything that is built is achieved by applying these same principles and using these same materials.
To understand the dynamic nature of most mechanical devices and systems requires a thorough mastery of forces and stresses, of vibrations and acoustics, of shock and impact, of deformation and fracture. Yet these are basic to virtually every product devised by people or found in nature. Automobiles are just one small example of where they are important.
Thus, the mechanical engineer is a designer who creates physical things of all sorts because the mechanical engineer's breadth of background is everywhere applicable. The mechanical engineer produces machines to build other machines, and thus is in the forefront of new manufacturing technology. In this role the engineer is faced with the task of building new things created by all kinds of engineers. This exposes the engineer to other technologies, and the mechanical engineer must be able to grasp their essence easily. For example, as the builder of energy devices to tap the oceans' resources, the mechanical engineer is simultaneously one of the oceanographers, one of the chemists, one of the environmentalists, as well as the master designer.
The mechanical engineer is comfortable working with people as well as with machines.
For example, the role in vehicle design is that of making technical advances in performance, efficiency, and cost while simultaneously meeting the life and comfort requirements of operators and passengers. Logically, then, the mechanical engineer is active in the new fields of biomechanics, biomaterials, biomedical fluid mechanics and heat transfer, air and water pollution, water desalinization, sensory aids, and prostheses.