The Never-Ending Days of Being Dead, by Marcus Chown

What happens when God calls time?

Reading this book is a little like being at a party (OK, a very nerdy one) with an almost perfect DJ. The tracks Chown plays - a mixture of the familiar and the cutting edge - are not records, however, but the highlights of recent attempts to answer some of the biggest scientific questions there are, from "What is beyond the edge of the universe?" to "Why do we experience a past, present and future?" In one chapter we learn why it is certain that there are other versions of us out there in the multiverse (here Chown refers to Larry Niven's story "All the Myriad Ways", in which characters faced with this knowledge of their doubles immediately kill themselves); in another we learn why scanning the universe for radio signals is not at all the right way to look for aliens (they probably went digital while we were still slime). Throughout there are the usual wonderful sentences that you only ever get in popular science books, such as "The important thing to realise is that, although our bubble-universe is a piece of decayed false vacuum which is no longer inflating, it is nevertheless surrounded by false vacuum which is continuing to inflate at breakneck speed". It's hard to resist.

One of the best chapters here deals with Stephen Wolfram and his theories of complexity. If you missed out on Wolfram when A New Kind of Science was published in 2002, then this is your chance to find out what is exciting about his theories, and how it is possible for the universe to have"emerged" out of a network programmed with a four-line algorithm even less complicated than 1) Create stuff; 2) Create more stuff; 3) Make the stuff interact; 4) Repeat until the end of time. Indeed, the idea of the universe as a vast computation in which matter is information crops up in several places in this book. Most profoundly it appears in the last chapter, "The Never- Ending Days of Being Dead".

Here we meet a familiar conundrum. What will humans do if, having somehow survived bird flu, global warming, the death of the sun, the end of our galaxy and so on (there is quite a lot of downloading involved in this, and cute little space probes into which we will, probably, pop our consciousnesses, and then zip off), we get somewhere close to the end of time only to realise that, well, the end of time means it's pretty much all over? How will we stop the great landlord in the sky throwing us out of the universe forever, and instead engineer some kind of cosmic lock-in?

The answer is simple. OK, it's not at all simple, but it goes something like this. Assuming that by that stage we are in control of all the matter in the universe, we should be able to prod it a bit so that when (and this is also assuming if) the Big Crunch happens, it happens in such a way that, as all the matter in the universe gets closer and closer together, it becomes faster and easier to use this matter to process information. The universe will then, apparently, eventually reach something called the "Omega Point", theorised by Frank Tipler in The Physics of Immortality. This is a point where its power is such that the universe can process an infinite amount of information. What happens after reaching the Omega Point - basically the end of everything - becomes immaterial since, if you could process an infinite amount of information, you could, at that point, simulate an infinite universe, or even run all the possible histories of the universe that there could ever have been. As in Zeno's paradox, the finish line will never appear. And this has an interesting, mind-blowing consequence, completely consistent with the laws of physics. As Tipler says: "One way or another, we are going to find ourselves resurrected in a computer simulation at the end of time". For reasons too complex to go into here, the final simulation will not be any old simulation; it will be just like Heaven. And the good news (especially for those still contemplating the existential implications of "All the Myriad Ways") is that if Tipler is right, then, on exiting this life, you go straight there.

Many contemporary popular science books tend to focus on one particular area and their authors will lead the readers slowly through every single step of the reasoning (usually, but not always, excepting the actual mathematics) that has led to the current way of thinking. You can buy very good books on string theory, network theory, emergence and so on. When you read a lot of these kinds of popular science books you become a kind of armchair expert not in quantum physics or relativity theory exactly, but in the 101 versions of these theories. You become able to think (wrongly) of a dimension as anything from a shower curtain to a slice of ham; and to explain a simplified version of Gödel's Incompleteness Theorem to friends even when quite drunk. This book covers so many subjects that although Chown tries to make sure everyone will keep up, you've only really got a good chance of romping through it if you have already taken these other 101 courses, preferably several times. If so, you will have a fantastic time reading this book (although you may wonder why you need to be told gently that water comes in molecules comprised of hydrogen and oxygen). If not, then be prepared to visit Wikipedia several times while you read.

In the end, this book does what the best popular science books do: it gives enough of an overview of each subject to make it exciting, and leaves you to pursue the primary texts yourself if you want to. In an age of over-specialisation in both the sciences and the humanities, and nowhere near enough true interdisciplinarity, we must all be grateful to writers like Chown who are able to make accessible work that in its crude form is not only inaccessible to outsiders, but unknown to them.