Under the sub-subject of cosmology, Amazon.com currently lists 5765 items. Among them there are textbooks, serious scientific discussions, popular books, books on history, philosophy, metaphysics and pseudoscience, mega-bestsellers like those by Stephen Hawking, Brian Greene and Lisa Randall, and works no one has heard of by authors as obscure as their books. It would almost seem as though the number of books on the subject is expanding faster than the Universe; that soon the nature of the missing mass will be no mystery – the dark matter is in the form of published but largely unread cosmology books. Does the world need yet another book about this subject? Why have I decided to contribute to this obvious glut on the book market? Why do I feel that I have something to add of unique value?

The idea for the current project had its dim origins in the year 2003 when I was invited to lecture on observational cosmology at a summer school on the Aegean island of Syros. I was surprised at this invitation because I am neither an observer nor a cosmologist; I have always worked on smaller-scale astrophysical problems that I considered soluble. In this career choice I was no doubt influenced by my first teachers in astrophysics, who were excellent but traditional and, to my perception at least, found cosmology to be rather fanciful and speculative (although I never heard them explicitly say so and almost certainly they would not say so now).

But I decided that this invitation was an opportunity to learn something new, so I prepared a talk on the standard cosmological tests (e.g., the Hubble diagram, the angular size–redshift relation and the number counts of faint galaxies) in the context of the current cosmological paradigm that is supported by modern observations, such as the very detailed views of tiny anisotropies in the cosmic microwave background radiation (CMB). The issue I considered was the overall consistency of these classical tests with the standard model – Lambda-CDM (ΛCDM).

I was actually more interested in finding inconsistency rather than consistency. This is because of my somewhat rebellious nature, as well as my conviction that science primarily proceeds through contradiction and conflict rather than through agreement and “concordance.”