author : Jack Cohen

We humans pass on more than genetic heritage to our children. We also pass on 'cultural capital'. This 'privilege' has enabled us to progress rapidly: no need to learn everything from scratch, no need to build everything from scratch.

But there is a price to pay. Too much captital leads to affluence, and then degeneracy and decline. This is nowhere more obvious than the fossilised educational establishment, protecting itself, rather than continuing to grow.

The first half of the book is a good overview of 'conventional' reductionist science, taking everything apart and looking at the content. It provides the background for the novel second half.

The second half puts everything back together, showing how complex systems can have emergent properties that appear at the 'whole' level, but be invisible on the 'part' level. Reductionism isn't enough, the context is crucial. This second half is necessarily less polished, because the authors are trying to pull concepts together in a new way. But it's a fun read, and very thought-provoking.

This extremely well-written book lucidly weaves together themes of self-organising complexity, co-evolution, cultural capital, and an explanation style that takes into account external 'complicity' as well as internal 'reductionist' ideas. It develops some of the authors' earlier ideas, in particular in The Collapse of Chaos. Stewart and Cohen take the view that in order to explain (human) intelligence, we need to understand its co-evolution with culture.

Evolution is explained using the mathematical idea of phase spaces, here the 'phase spaces of the possible'. Evolution progresses in directions constrained by its phase space, much as the behaviour of a dynamical system evolves in accordance with its phase space. The crucial ingredient, though, is that the phase space is determined by the existing system, and as the system evolves, so does the phase space. So the rules of the game change as evolution progresses. Some evolutionary changes make small 'private' changes to the phase space; the more interesting ones make qualitative, 'public' changes, opening up whole new regions of possibility not available before. For example, early bacteria produced a toxic by-product, oxygen; the new oxygen-rich atmosphere allowed whole new kinds of organisms to evolve. But the most interesting change in the rules of the game from our human perspective was the ability to pass on 'cultural capital' to the next generation, so that each new generation does not have to start from scratch: yolk in eggs, a nest as a protected environment, learning survival tricks from the troupe, and, eventually, being able to tap in to all of the 'extelligence' of human culture.

An interesting analogy with a 'snooker break' (if you don't know what that is, just read the book -- it's worth it!) is made, about how each generation needs to set up the right state for the next generation, not only for it to survive, but for it to be able to set up the right circumstances for its next generation, and so on. But as well as this stability, the rules of the game are always changing, so the system must also be flexible enough to keep evolving, or it will eventually fail to survive.

There is so much more here than I can summarise in this review. Hardly a page goes by without an interesting new idea or insight. We get the idea of human cultures providing a 'make a human kit', used to transmit the ideas needed to maintain the 'snooker break' of the culture itself. We get a reasoned explanation of the fallacy of Searle's Chinese Room argument, and a discussion of why Roger Penrose's approach to explaining intelligence is mistaken. We get the ideas of Dennett's 'multiple drafts' theory of emergent intelligence, as a 'pandemonium' of sub-intelligences, taken further, in an interesting chapter in free will, which also addresses the problem of genetic determinacy (with a wonderful little scene about a mythical gene for autoincarceration, which made me laugh out loud -- much to the confusion of the people around me!). And we get an optimistic speculation on the future of human evolution -- now cultural rather than physical -- and how our thinking is becoming more complex, rather than linear and simplex, as we discover and take account of the subtle ways seemingly unrelated events can interact. Read it yourself, and find out how much more good stuff is here.

Not only has extraterrestrial life been discovered, but it seems to be at war with us. That's the first conclusion when someone rearranges the moons of Jupiter to deflect a comet straight at the Earth. But maybe it's just a misunderstanding? A group of scientists is sent out Jupiter to try to make contact, and explain we'd really rather they sent the comet somewhere else. But the aliens turn out to be hard to contact, and the scientists need a bit of help from a maverick archaeologist and her animal-loving nephew.

This is in some sense the fictional version of the authors' Evolving the Alien, explaining just how alien aliens will be. They certainly succeed on the physiological front -- we get giant gasbags floating in the Jovian atmosphere, with a really weird genetics, and more. But I think they are less successful on the psychological front -- the aliens seem just extreme versions of certain human types.

The plot is rather uneven, and takes a while to get going. Once it does get going, it races along, with some nice twists and cliffhangers. There are zillions of coincidences -- but they are the kind I can almost forgive -- they are mostly used to explain parts of the plot (a sort of docudramatic infodump), and to reduce the cast of characters to a manageable level -- rather than to drive the plot off in unnatural directions.

But this is really a book of fun ideas. We get the physiology of the Jovian and other aliens, the explanation for ice at the lunar poles, the neo-Zen Buddhists, the mechanism to get to Jupiter in a hurry, the very cheeky explanation of the microwave background radiation, and lots of great little details. These ideas, and the whole plot-line, overcome the sometimes uneven, and occasionally clumsy, storytelling.

This is a book of advice to students about to embark on their first research, for a PhD. It covers the obvious areas, such as use of statistics, and how to write a paper and give a presentation, with most of the examples and anecdotes drawn from the biological sciences. However, the meat of the book, the philosophical core, if you will, is generally applicable, both to other areas of experimental research, and to researchers somewhat later in their career than studying for a PhD.

It starts with an introduction of some well-known puzzles, including deducing the colour of the bear, and the Monty Hall problem, in order to help examine assumptions, and get a feel for how paradoxical probability can be. (There is also an example about a pay rise that is bizarrely incorrect.)

After the introduction, the book settles down to its core message, of science being about asking good questions, and of experiments being about making good observations or measurements that help decide good questions. It emphasises that it is very important to understand the measurements being made, particularly if they are automated, and to understand how the choice of measurements affects what can be discovered.

It goes on to discuss various statistical approaches, the importance of raw data, and why statistical analysis is important, and needs to be understood, rather than simply done by rote.

But the philosophical core is about the difference between biology, sociology etc, and physical sciences. This key difference is the role, and origin, of variability. Most physical experiments try to reduce or control variability, because it is caused by experimental error; in biology variability is an intrinsic property of organisms, often the feature of interest to be studied, and so attempts to reduce it may produce results of such limited scope as to be worthless.

This is all very interesting, and helps to explain a key difference between the physical and biological sciences, and why techniques from one might not be readily applicable to the other. Yet in places some of the description and explanation seem rather over-condensed, particularly for its intended audience. Given how short the book is – barely more than 100 pages – I feel it would be greatly improved by being about, say, half as long again, with the authors explaining rather more of their interesting and important core philosophy.

For many years now Jack Cohen has been giving a lecture on "The Possibility of Life on Other Planets", or POLOOP for short. This is the book of that lecture, and it stresses just how alien alien life will be.

The main thrust of the book is that the astrobiologists have got it all wrong. They have too narrow an outlook, assuming that life has to be a 'carbon-copy' (lovely pun!) of 'life as we know it' on Earth. And yet the more we find out about the life on Earth, the more bizarre are the specimens discovered.

The authors prefer the term "xenoscience", as it allows a wider range of possibilities to be explored. Much of what we see on Earth is "parochial" -- an accident that happened once during evolution here, but would very likely not happen if evolution were run again -- five fingered limbs, elbows and knees, nose above mouth, and so on. The most convincing evidence against little green (or Grey) men isn't that they are little and green, but that they are men. The universals are more interesting -- eyes, flight, fur, photosynthesis, and sex seem to be some such universals, having evolved several times on earth. But it is a little difficult to work out what truly is universal, given the small sample space we have available. And even though "absence of evidence isn't evidence of absence", the authors are careful to point out that

Even so, they have nothing against more exotic life based on processes other than DNA, on other than carbon, or on other than chemistry (magnetic vortices in the sun, nuclear reactions on neutron stars, ...). The only requirement is for some process that supports sufficient complexity, and, as we are discovering, that's nearly anything. And life changes the world in which it lives.

So the universe is probably teeming with life. But looking for extra-terrestrial life with something like the SETI programme is probably doomed to failure. Aliens probably won't use radio, any more than they would use smoke signals. An even if they do use radio, it will be efficiently encoded and compressed.

Not all the book is about xenoscience. A lot of it is about science in general. We get digs at TV programmes:

We get tongue-in-cheek commentary on certain Big Science projects:

We get little interesting details about biology.

We get a calm and thoughtful tirade against pseudo-science of all stripes.

And we get lots of links to science fiction, one place where aliens get portrayed every day, for better (mainly books) or for worse (mainly TV: men in rubber suits). The text is dotted with little summaries of interesting fictional aliens, and comments on how SF writers have more imagination than astrobiologists.

One of the things the authors talk about is the "hidden book" behind the better SF tales: the book with all the science worked out to back up what gets foregrounded in the story. Jack Cohen himself has famously helped write several of these hidden books, albeit sometimes retrospectively! For example, the rationalisation of Star Trek's Tribbles is beautiful.

The content is certainly deep, interesting, and novel. So why "only" a 3.5 rating? Well, it's simply that I am left feeling that several layers of polish have been left off, and a few punchlines omitted. Some of the arguments could be better organised, and there is some repetition. If you've ever been to one of Jack's talks, this has a bit of their hop-scotch flavour: an interesting factoid here, a confusing allusion there, certainly all woven together to be very entertaining, and here with rather more depth and detail (but fewer cartoons!). But I would have like a little more in the book, some more of the "hidden book" that is behind this one. Don't get me wrong: I've been waiting for the book of POLOOP for ever, and maybe that has raised my expectations too high. This is a good book; I'm not sorry to have bought it in hardback. Yet the cover provocatively asks, "What does an alien look like?", and I still don't know.

Despite its title, this isn't a book about the science underlying Terry Pratchett's stories of Discworld -- that world runs on magic, after all -- it's about the science that governs Roundworld, our world.

It is structured as alternating chapters. The first of each pair tells the story of the Wizards at the Unseen University, and how a magical accident results in the creation of a pocket universe -- ours. With the unwilling help of Rincewind, they observe this puzzling universe as it evolves from the Big Bang to beyond our current time, and they try to understand in their own magical terms. The second of each pair of chapters then explains what the Wizards are observing from a scientific point of view.

The explanations build on ideas from Stewart and Cohen's earlier books, The Collapse of Chaos and Figments of Reality, including those of extelligence, and Ant Country. The ideas cover an enormous breadth, and because of this, there is necessarily some lack of depth, so it helps to have read the previous books to get some of this missing background.

It could also do with a "further reading" list. For example, they refer in passing to Deep Time -- that evolution operates over incomprehensibly vast periods of time, and so doesn't fit well with the kind of stories we tell about it -- and I would have liked a pointer to somewhere that explores this in more detail. There is rather a lot of this feeling that certain sentences have a lot packed into them, but with no pointer to somewhere to help the unpacking.

Lack of depth notwithstanding, I like this book. There are some nice points made about the way our high tech is beginning to look like magic from the outside, and some good discussions about the way "lies-to-children" -- over-simplified explanations -- are a necessary stepping-stone on the way to deeper explanations. [I was a bit taken aback to read on page 152: "In April 1969, Neil Armstrong stepped down onto the surface of the moon". This isn't a "lie-to-children", this is a simple factual mistake.]

In particular, I like the way the alternating fact and fiction chapters allow the separation of our current best understanding of the facts from the wildly speculative illustrative examples. The fictional details about evolution on Earth -- the rise of intelligence in certain crabs, lizards, and what not, only for them to be wiped out by the next ice age or meteor strike -- makes the point that our current civilisation is just as vulnerable to whatever the universe chooses to throw at us, but that the planet as a whole is very resilient.

So, some fascinating deep ideas lurking just round the corners. Maybe their next book will explore them further?

• The Science of Discworld, the Magic of Roundworld. Jack Cohen's talk at Reconvene '99 Eastercon

The first Science of Discworld gave us two parallel stories: the story of evolution on Earth, culminating with humanity escaping to the stars just before it was wiped out by yet another natural cataclysm, coupled with the story of the actual science behind it all. In this second volume we have the same format, with the (fictional) story being of how the humans got themselves that far, and the (scientific) story of how culture develops, and (nicely recursive here) the importance of stories within that culture.

The "plot" is this: evil misery-eating elves come to prey on the humans, by making them superstitious and thus fearful. The wizards try to stop this, but their first attempts make things even worse, until eventually they discover Shakespeare. The fun is seeing how (fiction) and why (science) they eventually succeed.

Like most Stewart and Cohen journeys, there is a lot packed into a small space, not always unpacked (or often, unpackable only if you've read previous travels), yet all fascinating nevertheless. We get excursions on chaos and complexity; on extelligence, cultural privilege, and the importance of stories; side-swipes at science, art, and religion; and loads more.

Some of the material has been covered before, but is well worth covering again and differently, because it is so import and difficult to intuit. The parts on DNA and complexity fall in this category.

Most of the work is taken up with examining the importance of stories in the development and continuation of culture. It would be interesting to speculate on how some of these ideas might be tested.

And towards the end, we get to see how science can help us make better stories, stories that are better suited to reality, rather than just how we would like things to be. Science stops us, and our stories, from fooling ourselves.

So, a fun read, and lots of food for thought (even if that food is served up as a splendid hors d'oeuvre course of masses of delightful toothfuls, rather than a good solid main course of meat and potatoes (although potatoes do play an important role...)).

In this third outing of The Science of Discworld, the authors have their usual fun, this time with evolution. The format is the same -- chapters describing how the Wizards of Discworld are trying to put right problems in their accidental creation -- our Roundworld, alternating with chapters describing the science behind it all. This time something strange has happened on Roundworld -- it seems that suddenly Darwin never wrote his Origin of Species -- and it put science back so that the people never escaped snowball earth 500 years later (don't ask -- just read the books!)

Evolution, Paley's watchmaker, and the history of Origin of Species gets an outing here -- as does a supporting cast of infinite numbers, cosmology, and complexity. It makes a fun read -- but it's probably not the best place to start, if only to understand many of the jokes about the Wizards attempts to change Roundworld.