In both physics and thermodynamic classes, students are taught that perpetual motion is impossible. Yet biology classes have been invoking perpetual motion to explain the origin of life ever since the idea of a self replicating RNA molecule took hold several decades ago. Intelligent design may not belong in school, but then neither do perpetual motion machines. See excerpt from chapter 10 of Intelligent Design or Evolution below:

Self Replication and Perpetual Motion

Researchers today are actively seeking and finding new ribozymes. Many are artificially engineered and others arise from random sequences. Many of these researchers believe that in time they will find a self replicating RNA molecule. Others like Joyce and Orgel who are at the forefront of the research disagree.

In chapter 7, several techniques used by life to circumvent the second law of thermodynamics were discussed. Unless a self replicating RNA molecule has the capability to implement some of these same techniques, its existence can be ruled out on purely theoretical grounds.

Based on fundamental laws of physics, science can state with certainty that if a self replicating RNA molecule is found, the molecule will only be able to replicate in a test tube. It will require a continuous supply of activated nucleotides to drive its replication. While this might work in the test tube, it will certainly not work in the primordial soup. Activated nucleotides in the soup will not last for more than a few days. Given that their decay will dominate any conceivable path for prebiotic synthesis, the soup will only contain at most a very dilute supply of activated nucleotides. Given the difficulty associated with the prebiotic synthesis of ribose, adenine, and cytosine, the concentration of these critical molecules in the soup will also be extremely low. This means that the first successful self replicating RNA molecule must be able to direct the synthesis of adenine, cytosine, ribose, uracil and guanine. If it cannot do this, it will not be able to replicate in the soup. Furthermore, it must be able to activate all of the nucleotides. So this special RNA molecule must know how to tap a plentiful energy source and use it to drive many different chemical reactions. If it cannot perform all of these functions, then it is a perpetual motion machine, and its very existence is limited to biology textbooks.

Figure 10.2: A Self Replicating RNA Molecule

In figure 10.2, the RNA molecule can exist in two states, folded and unfolded. When folded, it catalyzed RNA replication, and the formation of adenine, ribose, cytosine, uracil, and guanine. It also must create activated nucleotides (not shown). When unfolded, it serves as a template for replication. The folded version must also know how to replicate the unfolded version.

This particular ribozyme taps into sunlight as an energy source using a primitive form of photosynthesis. Other self replicating RNA molecules could potentially oxidize a chemical like methane, hydrogen, or sulfur to generate the required energy.

Figure 10.2 is what is required of a “living molecule.” Anything less is not alive. This figure was construted with due consideration to the second law. Any RNA molecule that does not possess all of the capabilities shown in figure 10.2 is a perpetual motion machine. It may replicate in the lab as long as it is supplied with activated nucleotides, but it will not replicate in the soup. Thus, it only exists in textbooks, and there is no need to wait to see if researchers can locate it.

Inventors have been trying to invent perpetual motion machines for at least 2000 years. They have all failed. Nevertheless, many have been issued patents by various governments throughout the world. Two examples of perpetual motion are shown in figure 10.3. Both examples are equally absurd. While many scientists apparently only recognize the absurdity of the first picture, nature can recognize both, and it does not allow either to exist.

Figure 10.3: Perpetual Motion Machines

The first picture in figure 10.3 is a clear violation of energy conservation. It does not work because the force that the magnet exerts on the car is exactly cancelled by the force that the car exerts on the magnet. The magnet does not cause the car to move. The second violation is more subtle only because it violates a different law of nature. When a self replicating molecule replicates, the replication decreases the entropy of the universe. The second law is violated. To get around this problem, any real self replicator must know how and be able to couple its replication to a plentiful energy source. If it is unable to do this, then it is a special type of perpetual motion machine, and it only exists on paper and in the imagination of researchers.

References:

1) Lee, Granja, Martinez, Severin, Ghadiri, “A Self Replicating Peptide,” Letters to Nature, 382:525-528, 1996.
2) Joyce, Visser, Boeckel, Boom, Orgel, Westrenen, “Chiral Selection in Poly (C) Directed Synthesis of Oligo (G),” Letters to Nature, 310: 602-604, 1984.
3) Joyce and Orgel, The RNA World, Gesteland, Cech, Atkins, Cold Spring Harbor, “Origin of the RNA World,” 1999.
4) Bartel, The RNA World, Gesteland, Cech, Atkins, Cold Spring Harbor, “Recreating an RNA Replicase,” 1999.
5) Ekland, Szostak, Bartel, “Structurally Complex and Highly Active RNA Ligase Derived from Random RNA Sequences, ” Science, 1995.
6) Bartel and Szostak, “Isolation of New Ribozymes from a Large Pool of Random Sequences,” Science, 261:1411-1418, 1993.
7) Thaxton, Bradley, Olsen, The Mystery of Life’s Origin: Reassessing Current Theories, Philosophical Libraries, 1984.
8) Orgel, Self-organizing Biochemical Cycles, Salk Institute of Biological Studies, 99:12503-12507, 2000.
9) Green, Szostak, “Selection of Ribozyme that Functions as a Superior Template in Self Copying Reaction,” Science, 258:1910-1915, 1992.