attuning to e
O
ur life is characterised by virtually unending repetition. Ecclesiastes sighed in the Old Testament: ‘There is nothing new under the sun; everything has been already’: the cyclical movement ebb and flood day and night schedules and timetables the rotation of the earth the vibration of the strings of a guitar vibrations in general: repetition, repetition. The basic condition of any vibration is the state, to which a system ‘automatically’ returns, a state of rest and a state of equilibrium. After the children have left the playground, all swings hang vertically again. This ‘automatic’ is actually not so automatic; here gravity is active. In the case of the swing,
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gravity may, therefore, be called the force that restores the equilibrium. This is why another force is also needed to set the swing in motion again. For instance, with very young children, the mother will give the swing a push. Or she pulls the swing seat backwards and then lets it go. Next, gravity ensures that the swing swishes down again. The fact that the swing continues to move is caused by the ‘inertia’ of the system, in this case by the mass of the child and the seat. Mass that has speed has the natural property of continuing with the same speed, as long as this is not prevented. Physicists call the property of wanting to maintain the acquired speed ‘inertia’. Without friction, a system that has been set in motion would continue to vibrate indefinitely. However, in practice, there is always friction, so that the swing will ultimately hang still. The time that the swing needs to go up and
