Cycles of time

Today's Wall Street Journal has a review I wrote of Sir Roger Penrose of new book cycles of time. The revision focuses on a much wider audience than this blog, and is the product of substantial edit to edit the length to get started and make it as readable as possible for as many people possible, so here are a few additional comments.

I must make it clear that I'm not convinced by what Penrose proposes. He must be the distant future of the universe to be conformally invariant, and all particles are massless. As far as we the electron is completely stable, with unchanging mass, and this will always ruin Conformal invariance. Penrose itself takes note of the problem. For this to be overcome, what is our ultimate understanding of how particles get mass change so that these masses to zero in the future. It is also seems to me that the Conformal anomaly of QCD will always be a problem, with quantization and renormalization group always Conformal invariance break and give a mass scale, indefinitely far in the future.

The other main problem is shared by most of the "pre-big-bang" ideas: how you ever test them? Penrose and a co-worker last year created a stir by claiming to see in the CMB patterns of the species he argues can be expected from black hole lapses late in an era before the Big Bang, but it's not clear there is a real prediction here, and others who have redone this analysis say they see nothing.

Attempts to create a Big Bang in our past and our future in General seems to me to be motivated by a very human desire to see in the global structure of the universe the same cyclical pattern of death and rebirth which human existence. For me, however, deeper understanding of the universe unexpected structures, fascinating precisely because of how strange to human concerns and experience. Just because we may have a cold, empty universe means an unattractive future not that that is not where things are headed.

The book is in many ways an unusual document. It includes a comprehensive annex from some of the details of the mathematics of his proposal to work. He has managed to make a trade publisher to get out of a highly technical discussion of a speculative idea within the covers of a popular book, instead of the usual route of publishing this in a refereed journal, in a sense. The only references I can find to other places where he some of this up are chapters in this book and this, if this contribution to a Conference procedure has written. The technical idea behind this, that the hypothesis of the disappearance of the Weyl curvature in the early universe which leads to possible cosmological models can be extended along the big bang singularity that he this paper of K.P. Tod attributes. There is a nice recent exposition of this by Tod here.

So, I'm not convinced by the speculation about the distant future, and for an evaluation of the ideas about extending back through the big bang singularity you need someone more expert on Cosmology than I do. These topics are very clearly marked in the book as speculative, without the support of other physicists or experimental evidence. The largest part of the book is all other material to provide a background and context the speculation, and that's what I think makes the most valuable as a popular book. Penrose is a beautiful, elegant and clear writer, and he handles a lot of ground about physics beautifully here. Most notable are the illustrations, by far the best visual representations of a series of important ideas that I know of. Physicists and mathematicians working with many internal pictures in their minds that important aspects of the concepts that they investigate, but very rarely do they have the technical skill to understand some of the essence of these photos and them down on paper. Even more rarely they make it in wide distribution in print, so I'm glad to see you here.

This entry was posted on Friday, may 27, 2011 at 11: 52 am and is filed under book reviews. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.