The Second Law of Thermodynamics and Evolution
Proponents of Creationism (and Intelligent Design, which is a sanitized
version of Creationism) attempt to use the Second Law of Thermodynamics
as a scientific argument against the validity of Evolution. Unfortunately
their argument is fundamentally flawed, in that its proponents try to use
it without understanding what the Second Law of Thermodynamics really says,
or what its implications are. Sadly this erroneous argument is believed
by many who read it, who see it as being somehow "scientific", but who
do not know sufficient science to realize that it is completely wrong.
The argument (as far as it goes)
Sounds good, doesn't it. Problem is, it is rubbish, borne out of ignorance
about the correct application of the Second Law of Thermodynamics
Man is a complex organism
Complexity implies a great deal of order, the opposite of disorder, and
so a state of lower entropy than existed when the atoms existed in a random
The Second Law states that entropy will always tend to increase.
The second and third points are inconsistent
Evolution cannot be responsible for the emergence of complex organisms
Therefore there must be a Creator.
What is wrong with the argument?
Not much, just the omission of a very important phrase "For an isolated
system, . . . ." in the statement of the Second Law. That doesn't seem
much, especially to someone who is not informed enough to appreciate the
subtleties of the science, but it is enough to completely invalidate the
argument in favor of creation mythology.
An isolated system is any one which does not interact at all with its
surroundings, either through the exchange of energy or by doing work. The
creationist does not seem to realize (or chooses to ignore) the fact that
the Earth is not an isolated system, it is not even close to being an isolated
system. We receive a tremendous amount of energy from the Sun, more than
enough to provide the energy needed to organize simple molecules into more
complex ones. Even though this does indeed to a lowering of the entropy
on the Earth, the drop is more than compensated for by the huge increase
in entropy of the Sun. Conclusion - the Second
Law of Thermodynamics does not in any way prohibit Evolution.
Entropy decrease in other non-isolated systems
Evolution of a complex organism is not the only example of a system whose
entropy can be made to decrease because of the influence of an external
agency. There are countless other examples. Here are a few.
Weather systems. The state of
maximum entropy of the atmosphere would be both a uniform temperature and
a uniform pressure worldwide. Clearly that is not the arrangement that
we see, the atmosphere is much more complex than that. There is a systematic
decrease in temperature as we move away from the equator towards the poles,
and superimposed on that a complex and ever changing pattern of weather
systems, with storms, high pressure regions, low pressure regions, pressure
gradients, gales, etc., etc., etc. All of these represent a high degree
of order (a decrease in entropy) when compared to the uniform condition.
Why can this occur? Because the Earth is not isolated. Out in deep space
where the Earth would be isolated these weather systems would not exist.
But we are not out in deep space, we are close (astronomically speaking)
to an enormous powerhouse known as the Sun. It's energy drives the decrease
in entropy which is required to organize that atmosphere into its different
temperature and pressure regions.
Hurricanes. (Also known as typhoons
or cyclones.) Hurricanes are one of the most extreme weather systems, and
are very highly organized and complex. They start as somewhat disorganized
small storms (although these are already partially organized, see above)
with a fairly random cloud pattern and only moderately strong winds. Given
time they can grow into a system with a well defined 'eye', a distinct
rotation (always counter clockwise in the northern hemisphere, which in
itself implies something other than the disorganization corresponding to
high entropy), a wall, and very strong winds of at least 74 mph and sometimes
200 mph, but with a calm center inside the eye. All of these require organization.
Does this imply a Creator? An 'intelligent hurricane', perhaps? Of course
not, it just means that there is an agency with the energy capacity to
drive the entropy decrease needed for the hurricane to develop, namely
the warm waters of the tropical oceans. If the hurricane becomes isolated
from these warm waters by moving over land then it does indeed become disorganized,
and falls apart rapidly. But while it was over the ocean, connected to
the warm waters, or if it moves back off the land onto the warm water,
it can draw on the ocean's thermal energy to become more and more organized,
decreasing its entropy by perfectly natural means.
Tides. The Earth's oceans are
organized into two high tide regions and two low tide regions. As the Earth
rotates each point on the Earth's surfaces experiences both high tides,
and both low tides, in approximately 24 hours. As with the previous two
examples, this organization of the ocean water represents a high degree
of order, and a lowering of entropy. The outside agency in this case? Principally
the gravitational pull of the Moon, with a smaller component from the gravitational
pull of the Sun. Perfectly natural, without any 'intelligent' agency at
Lightning. Lightning causes
a tremendous difference in the temperature of the gas in the discharge
channel and the temperature of the surrounding air. The cause of lightning
is a separation of electrical charges between the ground and the clouds
(or between clouds, or between different regions of the same cloud.) In
each case the charges have to be organized, positive charges here, negative
charges over there. That is an enormous decrease in entropy. Caused by
what? Thor(1)? An 'intelligent Van der Graaf Generator'(2)?
Neither, just a natural process driven by the Sun and its interaction with
Sand and water. A popular physics/chemistry
demonstration in which a mixture of sand and salt is separated in to a
pile of sand and a pile of salt(3). Now that's organization!
You might argue that you, the experimenter, are the 'intelligent
designer'. I'll agree that you are intelligent, but by no means are you
a designer. The solubility properties of sand and salt were in existence
long before were even born. You just took advantage of them. Besides, this
process does occur in nature outside of the laboratory, where salt is separated
from sediment and deposited on the shores of lakes (for example, see Mono
Lake in California or the Great Salt Lake in Utah.)
Molecules in a room. On the
page it was pointed out that the distribution of molecules in a room
should be perfectly uniform, corresponding to the state of maximum disorder
(entropy). In fact the distribution is not perfectly uniform, there are
more molecules in the lower half than in the upper half. True, the difference
is very small (unless your room is a mile high!) but it is there. The entropy
is therefore just a little lower than expected. Why? What caused the decrease
in entropy? An outside agency, namely the Earth through its gravitational
field which tugs ever so gently on each of the molecules. Nothing intelligent
Plant growth The Earth's biosphere
contains an abundance of nitrogen, hydrogen, carbon, oxygen, etc. When
dispersed throughout the biosphere these atoms have a high disorder, and
hence a high entropy. However, plants have to ability to organize these
atoms into more complex molecules, and ultimately plant material. But,
they can only do so by using some form of energy. This form of energy is
of course light, light from the Sun(4) which drives the process
known as photosynthesis. A natural process of ordering (and lowering of
entropy) which is not at all forbidden by the Second Law of Thermodynamics.
There are countless examples in which the entropy of one region decreases
quite naturally. There is nothing whatsoever in the Second Law of Thermodynamics
to prevent this. It does not require that the entropy must decrease, unless
the region is truly isolated. Providing an outside agency can provide the
requisite energy, decreases in entropy are perfectly permitted, as with
the case of evolution. The Second Law of Thermodynamics is no way prohibits
the process of Evolution.
Another misconception about evolution
Uninformed opponents frequently talk with some disdain about the 'Theory
of Evolution' as if it is an unsupported idea. The (perhaps understandable)
error arises from a difference in the use of the word theory in science
as opposed to its common usage. In science an unsupported idea is more
accurately termed an hypotheses. The word theory is used to describe a
possible explanation of a well documented observation. For example, we
might talk about Newton's Theory of Gravity as an explanation of what gravity
is. But in the end it wouldn't really matter if Newton's theory was wrong
(it is in fact an approximation), apples will still fall down from trees.
The same is true of evolution. We do have Darwin's Theory of Evolution,
as an explanation of how evolution proceeds (by natural selection.) There
are other alternative theories also. But even if Darwin's theory (explanation)
is wrong, even if all our current theories are wrong, evolution itself
is well supported by experimental evidence.
(1) Thor, Nordic god of Thunder
(2) Van der Graaf Generator, a laboratory device for producing high
voltages using the separation and storage of electric charges.
(3) First add water, and dissolve the salt. Filter the water to remove
the sand (which does not dissolve in water). Last, evaporate off the water.
(4) There are some plants (for example fungi) which use chemical energy
rather than sunlight.