Physics 101 continued - Motion

Of what does the study of physics consist?

Motion, heat, light, sound, electricity and magneism. All these are forms of energy.

Physics is "a consideration of the interrelationships of energy and matter."

In the latter half of the nineteenth century, physical techniques made it possible to determine the physical structure of stars, and the science of astrophysics was born. The study of the vibrations set up in the body of the earth by earthquakes gave rise to the study of geophysics.

The study of chemical reactions through physical techniques initiated and constantly broadened the field of "physical chemistry," and the latter in tyrn penetrated the study of biology to produce "molecular biology."

And of course, the discoveries of Madame Curie and her associates led to nuclear physics.

Assumptions
The notion that every form of substance has its natural place in the universe (a theory of the Greek philosopher Aristotle (384-322 BC) which stated that there were four elements: earth - at the center of the universe, water surrounding it, air over it, and fire over air. (We'll get to the fifth element later.)

An assumption [in scientific terms] is something accepted without proof, and it is incorrect to speak of an assumption as true or false, since there is no way of proving it to be either. (If there were, it would no longer be an assumption.)

It is better to consider assumptions as either useful or useless, depending on whether or not deductions made from them correspond to reality.

If two different assumptions, or sets of assumptions, both lead to deductions that correspond to reality, then the one that explains more is the more useful.
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Bibliography
Understanding Physics, by Isaac Asimov