A change is a transformation of materials. When materials interact, they change: they become different, they relocate, they take different forms. Change is what makes phenomena visible. Without change, there would be nothing to observe.
Matter is in a constant state of transformation. The wind moves dust across the road; iron rusts on the railing; bread rises in the oven; salt dissolves in water; ice melts in the cup. None of these are unusual events. They are the daily texture of a world in which materials are always doing something. To watch the world is to watch change happen.
Change of any type takes effort. Effort is what we put out to lift something, to push or pull, to stretch a rubber band or squeeze a ball. In science that effort is called energy. Energy is always associated with change; change is associated with matter; energy and matter are associated. Every transformation, large or small, is paid for in energy.
Change has a driver: chemical potential. Materials change because of differences in their potential, the same way water flows from a high reservoir to a low one. The differences may be in concentration, in temperature, in arrangement; the answer is always the same shape. Where there is a difference, there is a tendency to even out, and that tendency is what we observe as change.
Question
Where does change get the energy it requires?
Reveal Merrill's answer →Hide answer
From whatever has more chemical potential. Materials change because of differences in potential, the way water flows from a high reservoir to a low one. The flow is paid for by the difference. When the difference goes to zero, the change stops.