Recently, at a gasoline station, the driver at the next pump remarked that my pickup truck must use a lot more fuel than his compact car. He went on to confide that his father had driven a car that burned only water as fuel. His father's secret had been lost during a family squabble, but he was sure that his brother had the information If this secret could be uncovered, no one would need to worry any more about fuel economy. Clearly this man did not know enough about energy - especially conservation of energy. How much, however, do most people know about it? We speak of "energy extraction'' as though it is a substance that we mine. It is all around us in its various forms. In fact it may be
In planning a series of articles about the various forms of energy for
Access to Energy, I thought it best to start with a few words answering the question "what is energy?'' The problem is that I don't know. Richard Feynman, in Volume 1, p 4-1 of his freshman physics book, Lectures on Physics, with Robert Leighton and Matthew Sands, Addison-Wesley (1963), explains the difficulty of this question and also the law of conservation of energy with the following analogy:"Imagine a child, perhaps 'Dennis the Menace,' who has blocks which are absolutely indestructible, and cannot be divided into pieces Each is the same as the other. Let us suppose that he has 28 blocks. His mother puts him with his 28 blocks into a room at the beginning of the day. At the end of the day, being curious, she counts the blocks very carefully, and discovers a phenomenal law - no matter what he does with the blocks, there are always 28 remaining! This continues for a number of days, until one day there are only 27 blocks, but a little investigating shows that there is one under the rug - she must look everywhere to be sure that the number of blocks has not changed. One day, however, the number appears to change - there are only 26 blocks. Careful investigation indicates that the window was open, and upon looking outside, the other two blocks are found. Another day careful count indicates that there are 30 blocks! This causes considerable consternation, until it is realized that Bruce came to visit, bringing his blocks with him, and he left a few at Dennis' house. After she has disposed of the extra blocks, she closes the window, does
not let Bruce in, and then everything is going along all right, until one time she counts and finds only 25 blocks. However, there is a box in the room, a toy box, and the mother goes to open the toy box, but the boy says 'No, do not open my toy box,' and screams. Mother is not allowed to open the toy box. Being extremely curious, and somewhat ingenious, she invents a scheme! She knows that a block weighs three ounces, so she weighs the box at a time when she sees 28 blocks, and it weighs 16 ounces. The next time she wishes to check, she weighs the box again, subtracts sixteen ounces and divides by three. She discovers the following:
"There appear to be some new deviations, but careful study indicates that the dirty water in the bathtub is changing its level. The child is throwing blocks into the water, and she cannot see them because it is so dirty, but she can find out how many blocks are in the water by adding another term to her formula. Since the original height of the water was 6 inches and each block raises the water a quarter of an inch, this new formula would be:
"In the gradual increase in the complexity of her world, she finds a whole series of terms representing ways of calculating how many blocks are in places where she is not allowed to look. As a result she finds a complex formula, a quantity which
has to be computed, which always stays the same in her situation."What is the analogy of this to the conservation of energy? The most remarkable aspect that must be abstracted from this picture is that
there are no blocks. Take away the first terms [in the two equations] and we find ourselves calculating more or less abstract things. The analogy has the following points. First, when we are calculating the energy, sometimes some of it leaves the system and goes away, or sometimes some comes in. In order to verify the conservation of energy, we must be careful that we have not put any in or taken any out. Second, energy has a large number of different forms, and there is a formula for each one. These are: gravitational energy, kinetic energy, heat energy, elastic energy, electrical energy, chemical energy, radiant energy, nuclear energy, mass energy. If we total up the formulas for each of these contributions, it will not change except for energy going in and out."It is important to realize that in physics today, we have no knowledge of what energy
is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. However, there are formulas for calculating some numerical quantity, and when we add it all together it gives '28' - always the same number. It is an abstract thing in that it does not tell us the mechanism or the reasons for the various formulas.''[End of quotation] Virtually every aspect of the universe that is currently physically observable by human beings is a part of the energy equation. We therefore say that everything we observe is a form of energy, but we do not know what energy is.Fortunately, we do know how to convert some forms of energy into other forms of energy. We thereby control energy to a limited extent and manipulate the physical world in ways that we find useful.
In a nuclear power plant, mass energy is converted into heat energy and then into electrical energy. If we wished to be more detailed, we could mention the electromagnetic and kinetic energy in the nuclear decay products and the translational, rotational, and vibrational kinetic energy in the fluid driving the turbines.
The human body is a cleverly designed combination of different forms of energy about which we really know very little - not even the fundamental nature of energy itself.
We are not really very much more knowledgeable about energy than our colleague at the gasoline pump. The water his father allegedly poured into his automobile was a form of energy. No ordinary (non-nuclear) engine, however, can convert that mass energy into kinetic energy for an automobile.
|
|
Vol. 22, No. 2
Newsletter: Access to Energy Newsletter Archive Volume: Issues Issue/No.: Vol. 22, No. 2 Date: November 01, 1994 02:19 PM Title: Optimism vs. Pessimism
Copyright © 2004 - Access to Energy Newsletter Archive
|