Skip to main content

The Golden Ticket: P, NP, and the Search for the Impossible – Lance Fortnow ***

There is good and bad news early on in this book about the P versus NP problem that haunts computing. The good news is that on the description I expected this to be a dull, heavy going book, and it’s not at all. Lance Fortnow makes what could be a fairly impenetrable and technical maths/computing issue light and accessible.
The bad news is that frustratingly he doesn’t actually tell you what P and NP mean for a long time, just gives rather sideways definitions of the problem along the lines of ‘P refers to the problems we can solve quickly using computers. NP refers to the problems to which we would like to find the best solution’, and also that he makes a couple of major errors early on, which make it difficult to be one hundred percent confident about the rest of the book.
The errors come in a section where he imagines a future where P=NP has been proved. This would mean you could write an algorithm to very efficiently match things and select from data. Fortnow suggests that our lives would be transformed. This is slightly cringe-making as fictional future histories often are, but the real problem is that he tells us that the algorithm would make it possible to do two things that I think just aren’t true.
First he says that from DNA you would be able to identify what a person looks like and their personality. Unfortunately, these are both strongly influenced by epigenetic/environmental issues. Anyone who knows adult identical twins (with the same basic DNA) will know that they can look quite different and certainly have very different personalities. And they will usually have been brought up in the same environment. Fortnow is forgetting one of the oldest essentials of computing – it doesn’t matter how good your algorithm is, GIGO – garbage in; garbage out.
The other, arguably worse error is that he says that it will be possible to have accurate weather forecasts going forward X days. This is so horribly wrong. He should have read my book Dice World. The reason you can’t predict the weather at all beyond about 10 days is nothing to do with the quality of the model/algorithm, it is because the system is chaotic. Firstly we just don’t know, and never can know, the initial conditions to enough decimal places not to deviate from the real world. When Lorenz first discovered chaos it was because he entered the starting values in his model to 4 decimal places rather than the 6 to which the model actually worked. It soon deviated from the previous run. We can’t measure things accurately enough. The other problem is that the weather system is so complex – hence the slightly misleading title of Lorenz’s famous paper Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas? – that we can’t possible take into account enough inputs to ever have so good a model as to go forwards that far. Sorry, Lance, it ain’t going to happen.
For the rest, the first half or so of the book goes along pretty well, gradually opening up the nature of P and NP, the problems that are of interest and the ‘hardest’ NP complete problems. I found the main example, used throughout, a hypothetical world called Frenemy where everyone is either a friend or enemy of everyone else confusing and not particularly useful, but Fortnow gets plenty of good stuff in. After that it’s as if he rather runs out of material and it gets a bit repetitious or has rather tangential chapters.
Overall, despite the flaws, a much better and more readable book than I thought it was going to be – but probably best for maths/computing buffs rather than the general popular science audience.

Hardback 

Kindle 
Using these links earns us commission at no cost to you
Review by Brian Clegg

Comments

Popular posts from this blog

A (Very) Short History of Life on Earth - Henry Gee *****

In writing this book, Henry Gee had a lot to live up to. His earlier title  The Accidental Species was a superbly readable and fascinating description of the evolutionary process leading to Homo sapiens . It seemed hard to beat - but he has succeeded with what is inevitably going to be described as a tour-de-force. As is promised on the cover, we are taken through nearly 4.6 billion years of life on Earth (actually rather more, as I'll cover below). It's a mark of Gee's skill that what could have ended up feeling like an interminable list of different organisms comes across instead as something of a pager turner. This is helped by the structuring - within those promised twelve chapters everything is divided up into handy bite-sized chunks. And although there certainly are very many species mentioned as we pass through the years, rather than feeling overwhelming, Gee's friendly prose and careful timing made the approach come across as natural and organic.  There was a w

On the Fringe - Michael Gordin *****

This little book is a pleasant surprise. That word 'little', by the way, is not intended as an insult, but a compliment. Kudos to OUP for realising that a book doesn't have to be three inches thick to be interesting. It's just 101 pages before you get to the notes - and that's plenty. The topic is fringe science or pseudoscience: it could be heavy going in a condensed form, but in fact Michael Gordin keeps the tone light and readable. In some ways, the most interesting bit is when Gordin plunges into just what pseudoscience actually is. As he points out, there are elements of subjectivity to this. For example, some would say that string theory is pseudoscience, even though many real scientists have dedicated their careers to it. Gordin also points out that, outside of denial (more on this a moment), many supporters of what most of us label pseudoscience do use the scientific method and see themselves as doing actual science. Gordin breaks pseudoscience down into a n

Michael D. Gordin - Four Way Interview

Michael D. Gordin is a historian of modern science and a professor at Princeton University, with particular interests in the physical sciences and in science in Russia and the Soviet Union. He is the author of six books, ranging from the periodic table to early nuclear weapons to the history of scientific languages. His most recent book is On the Fringe: Where Science Meets Pseudoscience (Oxford University Press). Why history of science? The history of science grabbed me long before I knew that there were actual historians of science out there. I entered college committed to becoming a physicist, drawn in by the deep intellectual puzzles of entropy, quantum theory, and relativity. When I started taking courses, I came to understand that what really interested me about those puzzles were not so much their solutions — still replete with paradoxes — but rather the rich debates and even the dead-ends that scientists had taken to trying to resolve them. At first, I thought this fell under