Quantity versus Quality in Daily Life
At times of energy crisis, we are bombarded with speeches and articles on
how to “conserve” energy. Yet we all know that the quantityof energy is
already conserved. What is not conserved is the qualityof energy, or the
work potential of energy. Wasting energy is synonymous to converting it to
a less useful form. One unit of high-quality energy can be more valuable
than three units of lower-quality energy. For example, a finite amount of
thermal energy at high temperature is more attractive to power plant engi-
neers than a vast amount of thermal energy at low temperature, such as the
energy stored in the upper layers of the oceans at tropical climates.
As part of our culture, we seem to be fascinated by quantity, and little
attention is given to quality. However, quantity alone cannot give the
whole picture, and we need to consider quality as well. That is, we need
to look at something from both the first- and second-law points of view
when evaluating something, even in nontechnical areas. Below we
present some ordinary events and show their relevance to the second law
of thermodynamics.
Consider two students Andy and Wendy. Andy has 10 friends who never
miss his parties and are always around during fun times. However, they
seem to be busy when Andy needs their help. Wendy, on the other hand, has
five friends. They are never too busy for her, and she can count on them at
times of need. Let us now try to answer the question, Who has more
friends?From the first-law point of view, which considers quantity only, it
is obvious that Andy has more friends. However, from the second-law point
of view, which considers quality as well, there is no doubt that Wendy is the
one with more friends.
Another example with which most people will identify is the multibillion-
dollar diet industry, which is primarily based on the first law of thermody-
namics. However, considering that 90 percent of the people who lose weight
gain it back quickly, with interest, suggests that the first law alone does not
give the whole picture. This is also confirmed by studies that show that
calories that come from fat are more likely to be stored as fat than the calo-
ries that come from carbohydrates and protein. A Stanford study found that
body weight was related to fat calories consumed and not calories per se. A
Harvard study found no correlation between calories eaten and degree of
obesity. A major Cornell University survey involving 6500 people in nearly
all provinces of China found that the Chinese eat more—gram for gram,
calorie for calorie—than Americans do, but they weigh less, with less body
fat. Studies indicate that the metabolism rates and hormone levels change
noticeably in the mid-30s. Some researchers concluded that prolonged diet-
ing teaches a body to survive on fewer calories, making it more fuel effi-
cient. This probably explains why the dieters gain more weight than they
lost once they go back to their normal eating levels.
People who seem to be eating whatever they want, whenever they want,
without gaining weight are living proof that the calorie-counting technique
(the first law) leaves many questions on dieting unanswered. Obviously,
more research focused on the second-law effects of dieting is needed before
we can fully understand the weight-gain and weight-loss process.308 | Thermodynamics