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2.2. Science and Energy
At the most basic level of science, there is energy, which we can either store or use. The most fundamental storage of energy is matter, as Einstein identified in his famous equation E=mc2, where E is energy, m is mass and c is the speed of light. It does not take much material to create a very big bang. Energy moves through a medium (such as magnetic or electric fields) in waves.
Fig. 2.1 Energy storage and use by wave-matter conversion
We can also store energy by position, such as the potential energy gained when I put a can on a shelf. Energy can be stored as a potential where there are fundamental forces that attract or repel objects, as in Figure 2.2.. The attraction that holds the can on the shelf is, of course, between the earth and the can. The energy is stored in the distortion of the gravitational field.
This ‘potential’ stored energy can be found in batteries, springs, capacitors, balloons, fluorescent displays and many other devices. It is one of the amazing things about nature that the same patterns and even mathematical formulae appear across many different physical domains.
Fig. 2.2. Energy storage and use by movement
We cannot see stored energy, and it only becomes apparent when we use it, where it can be sensed in terms of movement, heat, light and the effects of electricity and magnetism. We can simplify these into two forms: movement and waves. Heat comes from the movement of atoms, whilst light, electricity and magnetism are all forms of electromagnetic radiation.
Although it seems that energy is used, this is not really true. When stored
energy is used, it does not disappear, it is simply converted from one form of
energy to another, and much inventing goes on around this conversion. When I
start my car, I want the fuel to be converted into direct movement, not heat and
sound (which is vibration of molecules), although it would not matter if
intermediate forms of energy are used: it is the leakage of these that causes
the problem. If we could convert energy efficiently, we would make life easier
and also be more ecologically sound.
Other parts of this section:
Other sections in this chapter: