This is a wondeful fund raising idea at Durham Cathedral. You pay a pound a brick. When we were last there 18 months ago it was just the base layer. I'd been thinking about using Lego for a lesson on entropy. The idea was based on the Brian Cox Wonders of the Universe episode where he goes to the desert in Namibia and builds a sand castle. He says that there are fewer ways of arranging the sand grains into a castle shape than if you were to arrange them into a random sand pile. I thought it might be more obvious in Lego and that with a small amount of Lego, we could even count the number of ways. Anyway - the cathedral. It is obvious that you can't just put the bricks together randomly and end up with something that looks like a cathedral. Yes, ther are many identical bricks. They could be numbered and swapped round and it would still look like the cathedral. So there are in truth a large number of ways of putting this set of bricks together and having it still look the same, But you can't swap a roof brick for a wall brick, for example. Now what if we only wanted a random pile of unjoined bricks, The order wouldn't matter, You could then swap roof bricks for wall bricks and get the same effect. There would be many more ways of arranging the bricks to get the same overall effect. Entropy is a measure of disorder. Entropy S = k.LnW where k is the Boltzmann constant and W is the number of ways the bricks can be arranged. The Lego Durham Cathedral has a lower entropy than a random pile of the same bricks. Order has a lower entropy than disorder.
