Preface to First Edition
A few decades ago, astronomy and particle physics started to merge in the common
field of cosmology. The general public had always been more interested in the visi-
ble objects of astronomy than in invisible atoms, and probably met cosmology first
in Steven Weinberg’s famous bookThe First Three Minutes. More recently Stephen
Hawking’sA Brief History of Timehas caused an avalanche of interest in this subject.
Although there are now many popular monographs on cosmology, there are so far
no introductory textbooks at university undergraduate level. Chapters on cosmology
can be found in introductory books on relativity or astronomy, but they cover only
part of the subject. One reason may be that cosmology is explicitly cross-disciplinary,
and therefore it does not occupy a prominent position in either physics or astronomy
curricula.
At the University of Helsinki I decided to try to take advantage of the great inter-
est in cosmology among the younger students, offering them a one-semester course
about one year before their specialization started. Hence I could not count on much
familiarity with quantum mechanics, general relativity, particle physics, astrophysics
or statistical mechanics. At this level, there are courses with the generic name of Struc-
ture of Matter dealing with Lorentz transformations and the basic concepts of quan-
tum mechanics. My course aimed at the same level. Its main constraint was that it
had to be taught as a one-semester course, so that it would be accepted in physics and
astronomy curricula. The present book is based on that course, given three times to
physics and astronomy students in Helsinki.
Of course there already exist good books on cosmology. The reader will in fact find
many references to such books, which have been an invaluable source of information
to me. The problem is only that they address a postgraduate audience that intends
to specialize in cosmology research. My readers will have to turn to these books later
when they have mastered all the professional skills of physics and mathematics.
In this book I am not attempting to teach basic physics to astronomers. They will
need much more. I am trying to teach just enough physics to be able to explain the