And this time we also know everything about the rest of the universe as well: we don’t need to predict it forward, we’re just given all the data about how it evolves (in fact I think that without loss of generality we can assume an empty universe outside the box, which reduces the data volume considerably). For both of them imagine a universe where everything is completely Newtonian, so no quantum mechanics in particular. It’s much more like the practice of medicine, as when you say: "I practice medicine." It means you do it every day. Let’s begin with some very down-to-earth ones, like money. To begin with, the clothes I am wearing are not those of a Buddhist priest, they are those of, say, a Japanese literary gentleman (which would correspond to the sort of person that I am), and they’re worn for the simple reason that they’re convenient and comfortable. Where does your head end and your neck begin? Or you could imagine that inside your neck is a big ball of lead, and you let that drop through your body, pushing the breath out as it goes until it reaches the floor, at which point you let it fall to the center of the Earth.

Just let it flow. When you really get swinging with an alleluia, it’s just… Now we want to predict where the balls go, and we’ll say that the prediction fails when a ball leaves a collision 90 degrees from where we predicted - it’s obvious that after that point we can’t usefully predict anything. Now we want to predict this system forwards and we’ll use the same criterion for failure: when some particle leaves a collision 90 degrees out from where we predict. The first case is billiards, and we’ll consider a completely idealised billiard table: completely smooth, flat and rigid, completely round balls with completely known properties (so how elastic they are etc), and the same for the cushions. The principles and skills of lock picking, once mastered, can be applied against the vast majority of commercial pin tumbler locks, and the basic tools, if somewhat unusual, are quite simple.

You can download the full game (7 megabytes), or else just look at the Read Me. You can download the prototype (300k), or just read the Instructions and overall description of the game. While some of these features can be defeated with conventional picking tools and are covered here, picking high security locks generally requires specialized tools and techniques (often designed for a specific brand or model of lock) and are beyond our scope here. Many of the principles can be applied to other keyed lock types, although sometimes the techniques and tools must be adapted. Few burglars can afford to risk exposure during the time required to pick even relatively easy locks, and unexplained possession of lock picking tools is often considered prima facia evidence of criminal intent. However, because the precision with which locks can be manufactured is limited by physical processes, materials, economics, and usability considerations, exploitable weaknesses almost always exist in practice. The first step toward learning to defeat locks is a thorough understanding of how they work, where their security comes from, what is billiards and how their design and manufacture introduces potentially exploitable vulnerabilities. Any physical security assessment should consider defenses against the full range of potential threats, not just vulnerability to lock picking.

Using the five or six pin lock, find a pick that lets you locate and lift each pin across its full range of motion without disturbing adjacent pins too much. Both of these are due to Michael Berry and are mentioned in a book called ‘A Passion for Science’ which is in fact a set of collected transcripts of BBC radio programmes from sometime in the mid 1980s: I heard them on the radio originally, and they have stayed with me - I didn’t find the paper versions until quite recently. If you can find a copy for sale, get it. Mechanical locks (and techniques for defeating them) are inherently interesting to many scientists, engineers, and others, and an understanding of the principles for evaluating and techniques for attacking locks, in addition to being useful in its own right, can provide subtle insight into security more generally. That is what we have been told we are. You may well have one of these locks on your house. Sawtooth rakes, such as the Peterson "Ripple" and the Falle-Safe rakes, have 5 or more very acute peaks along the length of the pick's edge.