Suppose that chamber 1 (figure 6.5) and chamber 2 (figure 6.7) are brought together so
that their walls touch. Heat can now be transferred between the systems, but the atoms are
confined to their respective chambers. Because chamber 2 is hot and chamber 1 is cold,
heat should flow out of chamber 2 and into chamber 1. Does such a flow increase the number
of available micro-states? Figure 6.9 and 6.10 show that this process increases the number
of available micro-states. The steady state (maximum number of micro-states) is reached
when energy is distributed equally among both chambers.
This example in meant to convey an intuitive feel for the second law,
what it means, and how it works. Keeping track of how micro-states change in real
processes is not practical. There are too many atoms and too many quantum states. The
number of available micro-states in most systems is far greater than the number stars in
the universe. Even with today’s powerful computers, there is no way to keep track of
this many states.
Fortunately, when the number of atoms is increased to 10,000 or more,
one distribution dominates. In figure 6.7, distribution three is the most probable. The
system will spend 60% of its time in one of the micro-states belonging to this
distribution. As the number of atoms is increased, the dominance of the most probable
distribution also increases. With 100,000 or more atoms, the system will spend all of its
time in the most probable distribution because the most probable distribution is always
the one with the most available micro-states.
Entropy is now easy to understand. As chemicals or atoms react and move
around, they try to find their most probable distribution. Since this is the distribution
that maximizes the number of available micro-states, it is also the distribution that
maximizes entropy. Thus, the entropy of the universe always increases.
Figure 6.9: Initial Distribution of Micro-states
Figure 6.10: Final Distribution of Micro-states
next: Entropy
home: Intelligent Design and the origin of life
|
