This is the second of four posts on the mathematical approach known as the Monte Carlo method, following ' Breaking the bank...' Moving from the bank being broken at a casino to a mathematical method occurred as the Second World War came to a close. A number of scientists on the US nuclear programme were attempting to model neutron diffusion from a nuclear bomb. This was because a conventional nuclear explosion is effectively the trigger for the (then theoretical) thermonuclear explosion of a fusion bomb - and a major factor in its effectiveness is how neutrons travel out from the primary fission stage. Like his colleague John von Neumann, the Polish-American physicist Stanislaw Ulam had an interest in the game of poker and the probabilistic nature of games. The new possibility of electronic calculation using the ENIAC computer made it possible to consider a novel approach to modelling neutron diffusion. At the heart of nuclear fission is the idea of a chain reaction. A neutron...

Credit: Tony French I am old enough to remember CND (Campaign for Nuclear Disarmament) marches, and generally speaking was always a bit wary of ban-the-bombists, particularly because there was a tendency to lump nuclear weapons in with nuclear power - I'm all in favour of a power source with very little impact on climate change - but the thought of nuclear weapons terrified my when I was younger and the threat seemed greater, and they still fill me with horror. After watching the leaders' debate on Thursday with interest, it struck me that the Labour party was missing out on a serious trick - something emphasised in today's quick defence of the nuclear deterrent after the Conservative attacks on the subject. After all, senior Labour figures have been ban-the-bombists in the past, and I think Labour should seriously consider adding not renewing Trident and scrapping the current 'nuclear deterrent' ASAP. There are several potential benefits: Huge savings - whi...

The news has been full lately of analysis of why many sources have been slow to donate to the Pakistan flood disaster. To be fair, the UK general public has been generous with over £30 million given already, but apparently worldwide, giving is lower than expected. Speculation in the media has been about the assertion that a flood seems less of a disaster than an earthquake (say) because it happens slowly and the thought of 'a bit of water' isn't as distressing as 'the earth open up and shifting.' Another possibility I have heard is that the TV reports haven't been showing enough close-ups of people, concentrating instead on sweeping shots of flood water where people appear small on the screen. The theory is this prevents personalization of the disaster, and if we think of it as impersonal, we don't identify. It's the same reason that many charities will tell you individuals' stories, rather than give the whole picture. I think there is one piece ...