There are a number of conservation laws in physics, and these are well-enough established to be pretty basic. Conservation of energy, momentum, angular momentum and mass are critical to the way the universe operates. But what do these laws mean?
Let’s start with the conservation of energy, ignoring for the moment the fact that under certain limited conditions it is possible to transform a very small amount of mass into a very large amount of energy, and vice versa. That’s nuclear energy, and we’ll get to it in another post.
Conservation of energy states that while energy can be changed from one form into another, the sum of all forms of energy is unchanged—energy can neither be created not destroyed.
Wait a minute, you may be saying. What about burning wood in my fireplace? Isn’t that producing energy?
It’s producing heat energy, yes—but the heat energy produced is balanced by the fact that the unburned wood has more chemical energy than the ash left behind in the fireplace. A very exact measurement, including the heat and light of the fire, the motion of air that it produces, and the increase in thermal energy of the fireplace itself, the smoke, and our hands held out to the fire, would show that the energy produced by the fire would be exactly the same as the chemical energy lost by the wood as it turned to ash.
Chemical energy, light and heat are by no means the only forms of energy. Two very important ones are gravitational potential energy and kinetic energy—the energy of any moving mass. If we think of a ball released on top of a hill, part of the gravitational potential energy of the ball will be transformed into the kinetic energy of its motion as it rolls faster and faster down the hill. Part, because part will be transformed into friction, both of the air and against the ground, which will ultimately reappear as heat.
Another form of energy with which we are very familiar is electrical potential energy. Electrical energy is convenient because it can readily be distributed by wires, but there is some heating of those wires and radiation of electromagnetic energy in the process, and thus a loss of electrical energy as heat. But the source of most of the electrical energy we use today is either chemical energy (fossil fuel or biofuels) or gravitational potential energy (hydropower.) Direct solar energy (energy of sunlight, or more correctly electromagnetic radiation) wind power (kinetic energy of the air) tidal energy (left over from the gravitational potential energy which created our solar system) and geothermal energy (generated by nuclear reactions in the Earth’s core) produce only a relatively small fraction of the electricity generated.
The point is, energy is not generated out of nothing. It is transformed from some other form of energy. Both biofuels and fossil fuels get their chemical energy from solar energy—the only difference is whether the solar energy is what is falling on the earth today or is stored solar energy from the distant past. Hydropower and wind energy are also driven by the sun.
In my science fiction book, abilities such as teleportation are subject to all of the conservation laws. When Derik asks Roi what he has to do for a balanced teleport to a higher elevation, Roi replies, “Move mass down to balance my mass moving up, same as levitation. The distance down times the mass I move down has to be the same as my mass times the distance I move up.” In this case, simple conservation of gravitational potential energy. But that’s not all he has to remember!