Most casual armchair scientists have no access to uniformly
smooth boxes and elemental gases, much less instruments to
measure the speed of the moving gases.
A metaphor for the gas chamber is found in the Lorenzian
waterwheel. This is a thought experiment. Imagine a waterwheel,
with a set number of buckets, usually more than seven, spaced
equally around its rim. The buckets are mounted on swivels, much
like Ferris-wheel seats, so that the buckets will always open upwards.
At the bottom of each bucket is a small hole. The entire waterwheel
system is than mounted under a waterspout.
Begin pouring water from the waterspout. At low speeds, the water
will trickle into the top bucket, and immediately trickle out through
the hole in the bottom. Nothing happens. Increase the flow a bit,
however, and the waterwheel will begin to revolve as the buckets
fill up faster than they can empty. The heavier buckets containing
more water let water out as they descend, and when the water is gone,
the now-light buckets ascend on the other side, ultimately, to be refilled.
The system is in a steady state; the wheel will, like a waterwheel mounted
on a stream and hooked to grindstone, continue to spin at a fairly constant
rate. But even this simple system, sans boxes or heated gases, exhibits
chaotic motion. Increase the flow of water, and strange things will happen.
The waterwheel will revolve in one direction as before, and then suddenly
jerk about and revolve in the other direction. The conditions of the buckets
filling and emptying will no longer be so synchronous as to facilitate just
simple rotation; chaos has taken over. The explanation for the irregular
movement of the gas lies at the molecular level. While the box sides may
seem smooth and thus the flow of the should always be regular, at molecular
levels the sides of the box are quite irregular due to the motion of atoms and
molecules. After all, in any solid not at absolute zero, total entropy is
positive and there must be some irregularity in the molecular structure of
the sides of the box. Molecular interactions are tiny, however. How would
such tiny things like slightly misplaced molecules affect the flow of the gas
in such a profound way as to cause seemingly random motion? The theory
behind how small deviations can lead to large deviations lies at the heart
of chaos theory. The explanation is simple, and in retrospect, obvious
explanation commonly known as sensitive dependence on initial conditions.