An Introduction to Modern Cosmology: new developments

Recently there has been lots of excitement about new microwave background results from the Boomerang experiment, which looks at irregularities in the microwave sky. The characteristic size of these depends on the geometry of the Universe, and it offers very strong support to the belief that the Universe has a flat geometry (k=0), as favoured by the inflationary cosmology.

In the meantime cosmologists have become increasingly convinced that our Universe does contain a low density of matter and a cosmological constant. The preferred cosmology is therefore a spatially-flat Universe with a density parameter Omega0 = 0.3 or so.

This is a good time to stress that if there is a cosmological constant, the simple relations between geometry and destiny of the Universe in Table 5.1 no longer necessarily hold. The cosmological constant allow such possibilities as a closed Universe which expands forever, or an open Universe which recollapses. In extreme cases there might not even be a Big Bang, though those parameters appear to be excluded by observations.

Back to the home page of the book's first edition.

Andrew Liddle
Last update: May 2000

I thought I should add something new to indicate that I do update this page from time to time. But as it happens things have been fairly stable and so there isn't really anything to add at this point. However you might be interested to know that a new edition of the book will be out in early 2003 which will include updates and quite a bit of extra material.

I will not be updating this page further once the second edition is out, but if you go to its home page you can read its new developments section.

Andrew Liddle
November 2002