Creationists who think that evolution violates
the 2nd Law of Thermodynamics, evolutionists who think that it
doesn't, anyone with a viewpoint on the issue, or anyone who is
curious and would like to understand: This quiz is for you.
If you know your basic thermodynamics, you
should have no problem with this quiz, and the quiz will answer
whether evolution thermodynamics does violate the 2nd Law. The
material covered in this quiz is taught within the first few
weeks of an introductory thermodynamics class, and consists of
the concepts of energy, absolute temperature, and entropy. If you
can't answer these questions correctly, then you don't really
The basic statement of the second law of
thermodynamics is in the form of an inequality, so some of these
answers should be expressed as inequalities. Ready? Let's begin:
- A body with temperature 6000 degrees Kelvin (K) loses
6000 Joules (J) of heat. Assume that the body is so
massive that its temperature can be treated as constant.
What is the change in entropy of the body?
- Suppose the heat lost is due to radiation of light. What
is the energy of the light that was radiated?
- What is the entropy change of the system including both
the light and the body?
- Therefore, how much entropy is carried by the light?
- Another body has temperature 300 K, and absorbs the
light. How much does the body's energy increase?
- How does the second body's entropy change in each of the
A. The energy of the absorbed light is immediately
distributed throughout the body, so that the temperature
remains virtually constant.
B. The light is absorbed by only a very tiny bit of
matter right at the surface. The matter heats up
enormously right at that instant, and vaporizes, expands,
floats up in the air, etc. (Think of evaporating water.)
- The second body on the average maintains a constant
temperature of 300 K. There are day-to-day and seasonal
cycles, but on the average the temperature is constant.
How much of the absorbed energy must it ultimately lose?
- The second body loses the energy by radiating infrared
light. This is heat loss, so how much does the entropy of
the body change? Again, assume that the body is so
massive that the temperature remains approximately
constant at 300 K during the heat loss.
- What is the net entropy change due to the combined
absorption and radiation? Use the conditions from
- The sun's surface temperature is approximately 6000 K.
The earth's surface temperature is approximately 300 K.
Three-fourths of the earth's surface is water. Sunlight
warms the earth's surface and evaporates water. The
earth's surface cools by radiation. Does the second law
of thermodynamics allow entropy on the earth to decrease?
If you wish, email me with your answers (as well as your comments), and I
will check them.