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Why Physics?

Today we think of science divided into separate fields, although this division occurred only in the last century or so. The separation of complex systems into smaller categories that can be more easily studied is one of the great successes of science. Biology, for example, is the study of living organisms. Chemistry deals with the interaction of elements and compounds. Astronomy is the study of the solar system, the stars and galaxies, and the universe as a whole.

Physics is the science of matter and energy, and includes the principles that govern the motion of particles and waves, the interactions of particles, and the properties of molecules, atoms, and atomic nuclei, as well as larger-scale systems such as gases, liquids, and solids. Physics is the science of the exotic and the science of everyday life. At the exotic extreme, black holes boggle the imagination. In everyday life, engineers, chemists, biologists, doctors, and many others routinely command such subjects as heat transfer, fluid flow, sound waves, radioactivity, and stresses in buildings or bones to perform their daily work.

Countless questions about our world can be answered with a basic knowledge of Physics. Why must a helicopter have two rotors? Why do astronauts float in space? How do CD players work? Why is there no hydrogen in the atmosphere? Why do metal objects feel colder than wood objects at the same temperature? Why is copper an electrical conductor while wood is an insulator?

The earliest recorded efforts to systematically assemble knowledge concerning motion came from ancient Greece. In the system of natural philosophy set forth by Aristotle (384-322 b.c.), explanations of physical phenomena were deduced from assumptions about the world, rather than derived from experimentation. It was the Italian scientist Galileo Galilei (1564 – 1642) whose brilliant experiments on motion established for all time the absolute necessity of experimentation in physics and initiated disintegration of Aristotelian physics. Within 100 years, Isaac Newton had generalized the results of Galileo’s experiments into his three spectacularly successful laws of motion, and the natural philosophy of Aristotle was gone.

By the end of the nineteenth century, Newton’s laws for the motions of mechanical systems had been joined  by equally impressive laws from Maxwell, Joule, Carnot,  and others to describe electromagnetism and thermodynamics. The subjects that occupied physical scientists through the end of nineteenth century – mechanics, light, heat, sound, electricity, and magnetism – usually referred to as classical physics.

The remarkable success of classical physics led many scientists to believe that the description of the physical universe was complete. However, the discoveries of X rays by Roentgen in 1895 and of nuclear radioactivity by Becquerel in 1896 seemed to be outside the framework of classical physics. The theory of special relativity proposed by A. Einstein in 1905 contradicted the ideas of space and time ofsdsd Galileo and Newton. In the same year, Einstein suggested that light energy is quantized; that is, that light comes in discrete packets rather than being wavelike continuous as had been assumed in classical physics. The generalization of this insight to the quantization of all types of energy is a central idea of quantum mechanics, one that has many amazing and important consequences. The application of special relativity and, particularly, quantum theory to such microscopic systems as atoms, molecules, and nuclei has led to a detailed understanding of solids, liquid, and gases and is often referred to as modern physics. Therefore, we must master the physics and its principles to understand the world we live in [1].

 

 

 

References :

 

[1] P. A. Tipler, G Mosca, Physics for Scientists and Engineers , 5th Ed. , Extended Version , 2004, W.H. Freeman , USA , 1335p.

 

Last Modification: September 2017

 

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