Egypt: the moment of truth
The Great Pyramid of Giza has lasted for 3,800 years. Hosni Mubarak has lasted somewhat less, but he would like to survive for a little longer. The difference between his regime and the Pyramid of Khufu is that it is an inverted pyramid. All its strength is at the top, but there is only a tiny point at the bottom. The laws of gravity and architecture tell us that such a structure is inherently unstable. The slightest push can bring the whole structure crashing down.