Ebook: Introduction to modern physics

'The purpose of this book is, frankly, pedagogical. The author has
attempted to present such a discussion of the origin, development, and
present status of some of the more important concepts of physics, classical
as well as modem, as will give to the student a correct perspective of the
growth and present trend of physics as a whole. Such a perspective
is a necessary basis—so the author, at least, believes—for a more intensive
study of any of the various subdivisions of the subject. While for the
student whose interests are cultural, or who is to enter any of the
professions directly or indirectly related to physics, such as engineering,
chemistry, astronomy, or mathematics, an account of modern physics
which gives the origin of current theories is likely to be quite as interesting
and valuable as in a categorical statement of the theories themselves.
Indeed, in all branches of human knowledge the ‘why’ is an absolutely
indispensable accompaniment to the ‘what.’ ‘Why?’ is the proverbial
question of childhood. ‘Why?* inquires the thoughtful (!) student in
classroom or lecture hall. *Why?’ demands the venerable scientist
when listening to an exposition of views held by a colleague.
Accordingly, if this book seems to lay somewhat greater emphasis on matters
which are frequently regarded as historical, or, if here and there a classical
experiment is described in greater detail than is customary, it is with a
desire to recognize the importance of ‘why.’