## Cosmological Horizons - useful books

Looking at books on this subject, it seems that there wasn't as much confusion in the past as there is now. Possibly this was because in the past the most distant objects known weren't that far away on a cosmological scale and so horizon questions seemed somewhat academic. But it also seems that people were happy to accept a 'special relativistic' interpretation of redshifts. Despite what is said in the

Expanding Confusion article, I don't think this caused great problems. There was known to be a theoretical limit to the observable universe, but this was equated with the particle horizon. For instance, the 1979 book

*The Red Limit* by

**Timothy Ferris**, which I had expected the to be all about horizons, was in fact more about the detection of objects further and further away. It seems that only later did the limit to the observable universe become linked to the Hubble sphere, and after around 1980 the confusion began to appear. For instance the editions of

*Principles of Cosmology and Gravitation* by

**Michael Berry** were published in 1976 and 1989. The explanation of horizons in this book certainly would certainly contribute to the confusion in the reader's mind, although I would think that the author is expert enough in general relativity to have the correct idea in his own mind.

### General books

As is to be expected, there are many books on cosmology which mention horizons in passing, in particular the particle horizon together with its associated problems. There's a more substantial discussion of the subject in

*Cosmology: The Science of the Universe* by

**Edward Harrison**. This book is made up of chapters which are to some extent independent of each other, and chapter 21 is about horizons. Another book at a similar level is

*Foundations of Modern Cosmology* by

**Hawley** and

**Holcomb**. For a book by a well known science author take a look at

*Impossibility* by

**John Barrow** . This isn't a cosmology book, rather it is concerned with limits to what we can know, but has a chapter on cosmology with a discussion of horizons. You might also find

*God's Equation* by

**Amir Aczel** useful. This gives an explanation of general relativity and its application to cosmology via a biographical account of the people involved in developing the subject, and has a short discussion of horizons.

### Online information

As well as the

Expanding Confusion paper and

Ned Wright's cosmology tutorial, you might be interested in

Graphical and Kinematical Approach to Cosmological Horizons which calculates the distances of the different types of horizon for various cosmological models.

### Textbooks

Information about horizons can be found in general cosmology textbooks such as

*Principles of physical cosmology* by

**P. J. E. Peebles** or the more concise

*Cosmology* by

**Michael Rowan-Robinson**. If you want a book with a bit more discussion of horizons then you could try

*An introduction to cosmology* by

**J. V. Narlikar** or the shorter

*An Introduction to the Science of Cosmology* by

**Raine** &

**Thomas**. Both of these are aimed at the undergraduate level student. Those looking for a more advanced book might be interested in

*Relativity* by

**Wolfgang Rindler
**.