6 Critical nucleus

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The magnitude of the field and temperature are the same as in preset 5, and the magnetization is mostly negative, the field positive. The initial conditions are chosen to give a cluster of up spins. (You may change this configuration by drawing in the display with the cursor with the left mouse button down. If you wish to store a configuration, choose store from the initial conditions menu; if you wish to retrieve the last stored conditions, choose recall or if already chosen, click on init.)

Run and see whether the cluster grows or decays. Click on init. to reinitiate the program once it is clear which way the system is going. Sometimes the cluster grows, sometimes it decays. If it's a 50-50 bet, then this cluster is of the critical size.