Sunday, February 15, 2009

Skeptical Sunday!

The Second Law of Thermodynamics

It’s often cited as refutation of evolution by creationists, and sounds pretty convincing if A) you take their definition as actually what the law says, and B) completely ignore the world around you. It’s usually phrased something like this...

“A system will always increase in disorder (entropy)” thus the argument goes that complexity cannot develop from simplicity, as any system will tend towards maximum entropy, thus evolution violates the second law of thermodynamics.

The real laws of thermodynamics deal with the exchange of matter and energy (remember, they are equivalent in a relativistic universe) within a system. It’s actually more complicated than it’s most often presented because it deals with some pretty abstract concepts. Simplifying it, while useful to convey the sense of it, robs it of its specificity and accuracy, and also leaves it open to misinterpretation.

It’s taken me weeks of research to feel confident enough to address the issue, and attempt a compromise between simplicity, and complete accuracy. The second law could be stated this way...

No exchange of energy will be completely efficient, and some of that usable energy will always be lost as heat. This process will continue until all the usable energy in the universe has not only been converted to heat, but that heat has spread evenly across the entire universe, and no information about the past is recoverable, because the universe will be the same energy level (temperature) in every square inch.

I hesitated to include that last clause, as the transmission of information is a complex subject. Anyway, energy is defined as “the ability to do work.” Heat is energy as well, but it is the most “disordered” state energy takes. Its disordered state means that it cannot be used to do work (per se! We might disagree about that definition as we use heat for a variety of uses, but just go with it, as our day-to-day definitions aren’t of any importance to the universe.) So, while disordered is somewhat accurate, it’s also misleading. Entropy is often defined as disorder, but it’s better stated as the dispersion of energy in a system, or that systems tend to go from less stable states to more stable states. In other words, the universe is working towards the most stable state it‘s capable of, which is an even distribution of its energy, and without energy being “concentrated” in one place or another, there won’t be any transfer of energy, or any work able do be done.

So, the second law (which is why there’s no such thing as perpetual motion) doesn’t have anything to say about complexity, whether it’s nuclear, chemical, or biological complexity. In regards to biological evolution, it pretty much obeys the law as far as it goes. Life forms go through a long chain of transformations to convert sunlight into other useful forms of energy (or matter, as the case may be), and they do it with less than perfect efficiency, and lose some of that energy as heat, contributing to the entropy of the universe. The second law of thermodynamics, while it does govern biological fuel consumption and uses, doesn’t at all forbid life forms from becoming more complex as they do so.

For example, we consume food, and thus grow, creating first our complex biological systems in utero, then as new cells (order) in our bodies as we grow older. While we develop and learn, our brains create new pathways, etc., etc. We are living examples of complexity developing from simplicity, and it requires energy to do so. All the second law warns us of is that we don’t get all the work possible from the energy we consume. Incidentally, the whole universe appears to be geared towards increasing complexity, so it comes as no surprise to me that biological life forms follow suit (years of study of chaos theory and fractals, and I still have barely scratched the surface. It’s why I went back to school, to get a new understanding of it by learning the math.)
Acorns, snowflakes, crystals, puppies, even nuclear fusion, are all examples of increasing complexity. The sun’s a beautiful example, really. It uses a tremendous amount of energy to fuse two hydrogen atoms into a helium atom, an arguable more “complex” element. That would be the work. In the process, some of that energy is lost as heat. Lucky for us, eh? Complexity happens all around us, all the time, it’s just going to cost the entire universe one day. Perhaps we should make the most of our time here, hmm?

So the universe couldn’t care less how complex a system is. Have at it, just realize that when it’s all said and done, no matter how complex a system gets, at some point there will be no more usable energy for it do so. That’s all, really. Nothing about how complex a system can or can’t be to use the energy, nor evolution, which incidentally, doesn’t assert that life forms must get more complex. Evolution is the theory that life forms change (evolve) over time to fill biological niches and pass on their genetic material, and they do so by natural selection determining which traits are passed on to successive generations (and boy is that an oversimplification!) Evolution couldn’t care less how complex you are. Bacteria are orders of magnitude less complex than we are, but have evolved to fill just about every niche there is, evolving a stunning array of diverse traits to do so.

So, add equal parts understanding of evolution and thermodynamics, bake for one semester of biology and physics, and viola, you have a complete dismissal of the “violation of the 2nd law” argument. For what it’s worth, creationists, you’d probably sleep better at night if you just looked at it this way: there’s what the Bible says God did, and there’s the actual universe, what God really did. The difference between the two could be thought of as only a matter of accuracy, not veracity. Think of it this way: the universe is like a skyscraper God built. The Bible is like a flyer advertising His services.

Mayhap this is a better analogy: the Bible is trying to describe a painting. When you look at the world around you, that’s actually looking at the painting. Science is analyzing the painting, looking at the brushstrokes, to see how it was painted. Even you’d have to admit, no matter how well written, the description doesn’t do the painting justice.

Random Act of Quotation!

“If you saw a heat wave, would you wave back?” Steven Wright


Nick Mangine said...

I remember listening to people make this argument in high school biology... it drove me nuts.

Here's another refutation of the second law argument: The earth is not a discreet system. It has a constant input of energy (from the sun). You can't look at part of a system and then apply laws of thermodynamics.

Nick Mangine said...

Oh, by the way, still planning to get back to your comments.