Preface Almost nine years ago, in 1999, I began a “What’s new?” page on my UCLA home page in order to keep track of various new additions to that page (e.g., papers, slides, lecture notes, expository “short stories”, etc.). At first, these additions were simply listed without any commentary, but after a while I realised that this page was a good place to put a brief description and commentary on each of the mathematical articles that I was uploading to the page. (In short, I had begun blogging on my research, though I did not know this term at the time.) Every now and then, I received an email from someone who had just read the most recent entry on my “What’s new?” page and wanted to make some mathematical or bibliographic comment this type of valuable feedback was one of the main reasons why I kept maintaining the page. But I did not think of trying to encourage more of this feedback until late in 2006, when I posed a question on my “What’s new?” page and got a complete solution to that problem within a matter of days. It was then that I began thinking about modernising my web page to a blog format (which a few other mathemati- cians had already begun doing). On 22 February 2007, I started a blog with the unimaginative name of “What’s new” at terrytao.wordpress.com I chose WordPress for a number of reasons, but perhaps the most decisive one was its recent decision to support LTEX A in its blog posts. It soon became clear that the potential of this blog went beyond my original aim of merely continuing to announce my own papers and research. For instance, by far the most widely read and commented upon article in my blog in the first month was a non-technical article, “Quantum Mechanics and Tomb Raider” (Section 1.1), which had absolutely nothing to do with my own mathematical work. Encouraged by this, I began to experiment ix

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