255Chapter 25Cosmology and the Universe:
The Big Bang, Dark Matter and
Dark Energy
Up to this point we have concerned ourselves with the general principals
and concepts of physics focusing both on their historic development and
their general impact on society. We have not explored the physical
universe, which constitutes our cosmic environment. We have spent
some time understanding the microscopic structure of matter but we have
not yet investigated macroscopic structures such as the continents, the
oceans, the Earth, the planets, the stars, the Milky Way Galaxy or the
universe as a whole. In this section of the book we shall tour the cosmos.
We shall investigate the nature and the origin of the planet Earth, the
heavenly bodies that surround it and the universe itself.
Images of the Universe
We begin by examining the structure of the universe. It is interesting
to follow the historical development of man’s concept of the universe.
We have already looked at some of the earlier notions of the cosmos.
The story of Kujum Chantu as told in Chapter 2 represents one of the
earliest geocentric pictures of the universe. The universe in these
primitive models consists of a flat Earth above which lies the vault of the
heavens frequently described as the inside of a giant cosmic bowl. Below
the surface of the Earth lies the dark underground region, the domain of
the dead. As more sophisticated concepts of the universe developed
during the Greek era the Earth was considered to be a sphere about
which the heavenly bodies — the Sun, the Moon, the five planets and
the stars — revolved. At this stage of development the universe did not