Recalling back the historical relation in the study of physics, although humans have been attempting to manipulate the physical environment, probably from the time when we discovered that we could cut better with a sharp stone than with teeth or fingernails, it could scarcely be stated that the science of physics began with a cave dweller. True, early inhabitants had already demonstrated and performed jobs in science. Likewise, all primitive people seem to have attributed its surroundings with natural phenomena, which they did not comprehend, to the presence of good or evil spirits, or to the manipulations of one god or several creatures. The stars, the sun, and the moon were the greatest wonders for centuries. Our interest in them led to the science of astronomy, which was one of the first offshoots of physics. One of the monuments to great technological skill is the Great Pyramid in Egypt, which was built about 2600 B.C. These massive structures required a keen knowledge of what we now call mechanics, a branch of physics that calculates the force required to move solid objects, even against opposing forces.
About 330 B.C., in the science career of Aristotle wrote his book, Physics, in which he laid down some principles that were accepted without question and governed people's thinking about the environment for a thousand years. Aristotle had not tested his theories, he had reached his conclusion by logic. So influential were his ideas, however, that when Galileo dared, 1000 years later, to challenge them, he was discharged from his position as a professor. Galileo is often called the father of the experimental method. Many persons also called him the first modern physicist. His most famous experiment may be the one in which he is said to have proved that all weights fall a the same speed by dropping a ten-pound weight and a one-pound weight from the Leaning Tower of Pisa. They hit the ground simultaneously.
Galileo's science job in astronomy, with the aid of a telescope, proved that the moon was not smooth. By mathematical calculations, he proved that the moon reflects the light of the sun. Sir Isaac Newton, born the year Galileo died, was one of the discoverers of calculus (with Leibniz). He discovered by experimentation the source of the rainbow. In the four centuries since Galileo demonstrated the value of conducting experiments to determine whether or not scientific theory may be valid, scholars have made great strides. Faraday conducted experiments that made the modern age of electricity possible. A generation later, Edison took advantage of his studies to produce more than 1,0000 inventions, including the incandescent light and the motion picture. This progress has been made because people turned their backs on speculation and began to undertake the tedious work of research.
Physicists' science careers have made great progress in recent years in probing the depths of the ocean and research into nuclear energy, communications, and aerospace. Most physicists are engaged in research. Those who teach in universities usually are also conducting research programs or are supervising the research of graduate students. Because there are many specialties within the field of physics, physicists will often focus their research efforts on one or another of the special fields. Physics may be differentiated roughly into two fundamental divisions. One, mechanics, has to do with the motion inherent in solids, liquids, and gases. The other, statics, is the study of matter at rest and is closely allied with the study of engineering. Designs of dams and bridges are related to the physical problems in statics. However, physicists are coming to believe more strongly that nothing really is static, and matter only seems to be at rest. Matter is defined, briefly, as that of which any physical object is ''composed'' or whatever occupies ''space.''
As to science employment, physicists who are employed by industry devote their attention to the problems of the kind of enterprise represented by their own firm. For example, a physicist may be employed by one of the petroleum industries engaged in conducting experiments that relate to improving methods of obtaining crude oil, or of refining or using it. On the other hand, aerospace industries employ physicists to conduct research into problems peculiar to their own operations. Indeed, the knowledge and skills of the physicists have brought priceless contributions to science and some industrial undertakings.
