Wednesday, March 18, 2009

Second law of thermodynamics

While this may not make for a very interesting debate, I agree fully with Kurt's assessment of the relationship between biological life and the second law of thermodynamics. I would, however, like to expand upon his original statements.

The second law of thermodynamics states that a reaction within a closed system which is not in equilibrium will progress in a manner which increases the entropy of the system. Mathematically, entropy is equal to the change in heat produced by a system at a given absolute temperature. In most chemical reactions, heat represents an amount of energy which is lost, and is unable to perform work. So, a simplified interpretation of this law can be stated "it is more favorable for a reaction to produce heat than to perform work". Once the concept of energy gradients is introduced (which would take far to long to explain so you will just have to believe me) this law can be read as "Reactions must proceed in an energetically favorable manner, and no reaction is perfect". This is a far cry from the common interpretation of "the universe moves towards chaos" that so many spew as known fact.

The application of this theory to biochemistry can be easily seen. Biochemical reactions always proceed in a manner which is energetically favorable. Organisms have three ways of dealing with energy: they can use it, store it, or transfer it from one carrier to another. Organisms also have the ability to accomplish non-energetically favorable reactions by coupling them with energetically favorable reactions. The best example of this is the reaction by which adenosine triphosphate (ATP) is made. ATP is the energy currency that organisms use to power almost all of their chemical reactions, because the phosphate bonds within the molecule contain an enormous amount of energy which is relatively easily release (usually via an enzyme called ATPase). But how do we make ATP? How do we organize and create these high energy bonds? By transferring the energy from one source to another. In order to produce ATP (this is the main mechanism, there are many others)organisms use a series of enzymes and transport proteins to pump protons from one side of a plasma membrane to another. This creates an electrochemical gradient (lots of positively charged protons on one side of the membrane want to come through to the other side to balance both the electrical charge and proton density across the membrane). Because the protons can not freely diffuse across the membrane, they have to return through a molecular machine known as ATP synthase (sometimes called ATP synthetase as well, biochemists are very creative in their naming). The ATP synthase utilizes the energy being disbursed as the protons move down their electrochemical gradient to package the constituent pieces of ATP together. The net result of this process is the creation of ATP and the generation of heat.
In this situation, the body has become more efficient at producing heat, and thus moving towards entropy, than a non-living object. It has taken a reaction which would normally not occur and allowed it to proceed in an energetically favorable manner.
More than this, however, the body has a mechanism which is designed purely to increase the heat(entropy) of the system without performing any meaningful work. This is the process of non-shivering thermoregulation. During this process, the body uncouples the proton transport system from ATP synthase, allowing the proton gradient to disburse without performing any work. Thus most of the energy produced is simply released as heat. While this serves the purpose of warming the person, chemically it does nothing but move the system towards equilibrium while increasing entropy. This makes the organism, at that given time, a very efficient (HA!) entropy machine.
Again I would like to point out that none of this is evidence for or against God, it simply shows that human understanding of one system does in fact coincide with the human interpretation of another system. Personally, I think it takes a good deal of faith to believe that these systems just randomly congealed out of a soup of chemical reactions. But hey, I'm not a doctor...

2 comments:

Kurt Pankau said...

Just to clear the air.

I never said that the second law of thermodynamics had anything to do with God. I simply stated that the Young-Earth Creationist movement will frequently argue that this law contradicts evolution by way of their "universe = chaos" interpretation of it and that they are wrong. I wasn't even concluding that, I was merely referencing it on my way to another joke.

Once the discussion was reshaped (by you) into Science-v-God (cage match on PPV), I stated that I didn't think they were diametrically, but that they certainly fought a lot, but at that point we weren't talking about thermodynamics anymore.

Also, poop.

Kurt Pankau said...

By "diametrically" I actually mean "diametrically opposed".

Also, pooooooooooop!