Recent discoveries in cosmology have changed this science drastically. In a new world picture emerging now, the major feature is the "dark energy" of vacuum which contributes about 3/4 to the total energy of the observed Universe. Predicted theoretically by Einstein in 1917, this unusual cosmic energy produces not gravity, but antigravity. Antigravity makes the Universe expand with acceleration.
This is one of the first books in current literature which treat the newest most exciting ideas and discoveries in the science of the Universe. The book provides an easy introduction to both classic foundations and modern developments in cosmology for students, as well as interested physicists and astronomers working in other fields. Only a basic background in calculus, differential equations, and vectors is expected from the reader. Throughout the text, boxes present interesting side areas or background material while exercises promote active understanding.
Cosmology has seen
phenomenally rapid developments in the last few years. These developments have
created a need for textbooks which include fully the latest observations and
theory. We want to give students the foundations, both analytic and
observational, for modern cosmology. We describe how what were once new ideas
became part of the solid present-day foundations, facts or concepts likely to
endure. On the other hand, from this experience, we know that frontier
observations or concepts currently on the edge of verification and acceptance
may well extend our future understanding of the universe as has happened
Our approach is on the conservative side, and thus we do not spend much time
with topics like the inflation theory where fashions are likely to change many
times even before this book comes out of print. Thus this text is not meant as
a course in Astro-Particle Cosmology, even though we treat some current ideas
of this field also. A good introduction to cosmology with particle physics emphasis
is given in the book by Matts Roos Introduction to cosmology (Wiley, 2003).
It is our experience, that the best students should not
only be presented with well-established ideas, but also should see more
speculative frontier material to excite their interest and active thought.
A bit of this is found also in this text, mostly in the last chapter.
Beside the main text, we often present boxes, containing either a digression
into an interesting side area or background material. Scattered through the
text, at appropriate locations are problems or exercises to enable better
The present text grew out of lecture notes for the courses on Physical
Cosmology, Galactic Evolution and Galactic Dynamics which the authors have
given over the years in University of Turku and in University of Alabama. They
form part of the advanced undergraduate program of the universities. These
programs have separate courses in Astro-Particle Cosmology, which we do not
The students are expected to have completed their studies in intermediate
physics (e.g. at the level
of the textbook by Alonso \& Finn: Fundamental University Physics) and
to have had the first course in Astronomy (using e.g. the textbook by
Karttunen et al. Fundamental Astronomy). Since it is our
experience that students often have gaps in their knowledge even at this level,
we have tried to explain the key concepts starting from the basics. Thus the
level of the book is adjusted according to our experience of teaching the
courses over the years. We assume a background in calculus, differential
equations, and vectors.
A modern cosmology course cannot be taught without General Relativity. It is
not possible to understand gravity, in particular antigravity, without going
into some details of the theory. This is a major obstacle since students at
this level have had no exposure at all to General Relativity. On the other
hand, a good introduction to General Relativity would consume the whole course.
Here we have made a compromise where the theory has been explained as far as
possible without the techniques of tensor calculus. An appeal to the Newtonian
limit is made repeatedly, and calculation techniques familiar from Classical
Mechanics (i.e., Lagrangians) are used. By skipping the Boxes one may avoid
tensors almost totally in this course.
Our point of view on antigravity is that it is a manifestation of Einstein's
Lambda-term. As to the other key concept, dark matter, we take the position
that it is likely to be cold and composed of weakly interacting massive
particles which have so far not yet been discovered. It is likely that this
view, LambdaCDM for short, will be dominant for some time to come, and even
if it is finally modified or replaced by something else, it is necessary for
the students to learn this theory.
Another shortcoming in the usual intermediate physics curriculum is the brevity
of hydrodynamics. To help with this problem, we have carried out rather
elementary derivations, in preparation for the discussion of small density
perturbations in the early Universe. This is another key area necessary for the
understanding of the processes of local physics.
The LambdaCDM has many consequences which have not been fully appreciated
in older textbooks: the evolution of galaxies via multiple mergers of smaller
dark matter halos, the key role played by supermassive black holes in the
evolution of the stellar systems inside these halos, the population of
intergalactic supermassive black holes which arise through the slingshot
process subsequent to the mergers, etc. We have presented these new topics of
the standard theory in considerable length.
Much of the cosmological observations today deal with correlations of galaxy
distributions and of the anisotropies in the microwave background radiation. We
spend considerable time in explaining the key concepts and also go to the
analytical theory. Even though there are now wonderful numerical simulations of
the evolution of cosmic structure, they may hide the deeper understanding of
the related physics in the large numbers of parameters and assumptions
necessary to set up such experiments. Ideally, we would like to test the
fundamental theories using computer experiments as well as observations.
The evidence for dark matter has grown steadily over the years. We review the
evidence for dark matter as well as the techniques of observing it. Especially,
gravitational lensing has provided a new way of "seeing" the dark matter. We
explain the gravitational lensing theory in considerable detail since it is
likely to be the way of the future in studies of dark matter and galactic
The authors would like to thank the hospitality of the University of the West
Indies, St.Augustine, Trinidad where the authors have met to coordinate their
efforts and one of the authors (M.V.) did most of the writing. Similar
meetings in St.Petersburg Russia, The University of Alabama, and Turku,
Finland have been essential to this project, and support from the relevant
institutions are gratefully acknowledged. Financial support for this work has
been provided by the Academy of Finland through the project "Calculation of
Orbits" and the United States National Science Foundation Grant AST020177 to
Bevill State College in Fayette, Alabama. Authors thank Kimmo Innanen, Sverre
Aarseth, Chris Flynn, Pekka Teerikorpi, Yuri Baryshev, Yuri Efremov, and Bill
Saslaw for reading part of the manuscript and for valuable comments. The final
version of the manuscript was put together by Sethanne Howard whose help has
been invaluable. Besides the text itself, she has worked on most of the illustrations.