Benard Cell Convection

Consider a thin layer of water sandwiched between two horizontal glass plates. Suppose the system is at room temperature and in thermal equilibrium with its surroundings. One region of water looks pretty much the same as any other. If the water is now warmed from below so that energy is allowed to flow through the system and back into the environment above, the system will become self-organized above a certain critical temperature. If you look down at the system, you will see a structured, honeycomb pattern in the water (see figure 7.1).

The cells in the honeycomb—often shaped like hexagons or pentagons— are known as Benard cells and are rotating convection cells. Water warmed at the bottom rises; as it rises it cools and starts to sink again to the bottom to be rewarmed, thereby repeating the process. Water cannot both rise and fall in the same place, so regions where water rises become differentiated from

Benard Cells

Figure 7.1. Simulation of Benard convection cells in a Petri dish. The cells have similar size, except on the border. Although the shapes of the cells vary somewhat, they approach a hexagonal structure commonly called honeycomb. The emergence of an organized structure from a homogeneous medium such as water or oil is startling.

Figure 7.1. Simulation of Benard convection cells in a Petri dish. The cells have similar size, except on the border. Although the shapes of the cells vary somewhat, they approach a hexagonal structure commonly called honeycomb. The emergence of an organized structure from a homogeneous medium such as water or oil is startling.

regions where it falls. This differentiation gives rise to the cells. Seen from the top, the cells have a dimpled appearance, since water rises up the walls of the cell and flows toward the center dimple to flow back down again, completing the convective circulation (see figure 7.2).

The cells are visible because of the effects of temperature on the refraction of light. The way in which one cell rotates influences the ways in which its immediate neighbors rotate; in turn, the first cell is influenced by them. By adding thermal energy to water, we have brought about the spontaneous emergence of a complex system of interacting convection cells. The spatial and temporal order we can see in the behavior of this self-organizing system is not imposed from outside. The environment merely provides the energy to run the process. Chance, in the form of environmental fluctuations, provides the initial local inhomogeneities that serve as seeds for the emergence of the system from an initially homogeneous aqueous medium. The Benard-cell patterns result from the energy-driven interactions of the components (water mol ecules) internal to the system. Benard cells are not just an artificial phenomenon: astronomers have seen these cells on the surface of the sun.

Self-organizing systems, such as the Benard-cell system, constitute a threat to Dembski's creationist enterprise because, although these systems are both undesigned and naturalistically explicable, they manifest complex specified information and thereby give the misleading appearance of being the fruits of intelligent design.

Apparently aware of the threat posed by self-organization of this kind to his claims about intelligent design, Dembski (2002b) initially accuses those who study these phenomena of trying to get a free lunch:

Bargains are all fine and good, and if you can get something for nothing, go for it. But there is an alternative tendency in science that says that you get what you pay for and that at the end of the day there has to be an accounting of the books. Some areas of science are open to bargain-hunting and some are not. Self-organizing complex systems, for instance, are a great place for scientific bargain-hunters to shop. Benard-cell convection, Belousov-Zhabotinsky reactions, and a host of other self-organizing systems offer complex organized structures apparently for free. But there are other areas of science that frown on bargain-hunting. The conservation laws of physics, for instance, allow no bargains. (23)

Yet Benard cells occur in nature (for example, in the sun) as well as in the laboratory. Their existence is certainly consistent with known conservation laws.

Dimple

Wall of Cells

Wall of Cells

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1

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1

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Celll

Cell2

Figure 7.2. Cross-section of Benard convection cells. Warm water rises up the wall of the cell, cools, and sinks down at the dimple in the middle of the cell.

Dimple

Celll

Cell2

Figure 7.2. Cross-section of Benard convection cells. Warm water rises up the wall of the cell, cools, and sinks down at the dimple in the middle of the cell.

The matter is made all the murkier because Dembski says elsewhere that he finds the existence of Benard cells to be unproblematic (which seems to contradict his suggestion that they violate the conservation laws of physics). Thus, he observes:

Benard-cell convection, for instance, happens repeatedly and reliably so long as the appropriate fluid is sufficiently heated in the appropriate vessel. We may not understand what it is about the properties of the fluid that makes it organize into hexagonal cells, but the causal antecedents that produce the hexagonal patterns are clearly specified. So long as we have causal specificity, emergence is a perfectly legitimate concept. (243)

Here Dembski is guilty of gross oversimplification in his attempt at an easy rebuttal of a difficult problem.

What actually happens "repeatedly and reliably" is a pattern involving some arrangement of rotating convection cells (often involving both hexagons and pentagons), where the rotation of one cell reflects and is in turn reflected by the rotations of its neighbors. But we do not get the same pattern (including rotation dynamics) each time we run the experiment. The actual pattern generated in a given trial reflects both the Benard-cell convection mechanism and the effects of chance inhomogeneities and fluctuations in the fluid medium. In consequence, the precise patterns generated in a sequence of trials exhibit a high degree of variation. These contingent patterns are nothing like the results of an automatic pattern-generating mechanism that gives the same result repeatedly and reliably, time after time: the Benard-cell patterns also exhibit complex specified information.

To see this, consider once again the patterns generated by Dembski's archer, who intelligently and skillfully designs the trajectories of his arrows to hit the bull's-eye of a target from a great distance. A pattern of several hits in the bull's-eye is complex because it has a low probability of happening by chance alone. The general form of the pattern—a pattern involving hits in the region of the bull's-eye—can be specified in advance (or independently) of the shooting of the arrows. That the pattern of hits is skillful and not the result of an automatic pattern-generating mechanism is manifested in the observation that, whenever the archer shoots several arrows to demonstrate his skill, he does not repeatedly and reliably get exactly the same pattern of hits in the region of the bull's-eye. The actual patterns of hits generated in a sequence of trials are contingent.

Benard-cell patterns are complex: they involve the coordinated motions of trillions of water molecules, and the probability that they would form by chance alone is minuscule. As with the archer, the general form of the pattern, involving some arrangement of rotating hexagons and pentagons, is specifiable in advance (and independently) of any given trial. As with the archer, the actual pattern generated on any given trial is contingent. You do not get exactly the same pattern repeatedly and reliably each time you run the experiment. The crucial difference between the Benard-cell pattern and the archer's pattern of hits is that the Benard-cell pattern does not require intelligent design or skillful manipulation for its appearance, only the combined effects of a dumb pattern-generating mechanism and mindless chance in the form of fluctuations and inhomogeneities in the fluid medium.

The problems posed by Benard-cell patterns for intelligent-design theorists such as Dembski do not end here. As we saw at the beginning of this chapter, Dembski claims that information is the inverse of entropy. The emergence of the Benard-cell patterns involves a local decrease in entropy (that is, a decrease of disorder or an increase of order). It follows from Dembski's claim that, when Benard cells form, as entropy decreases, information increases. But this increase of information does not involve any input or use of complex specified information arising from intelligent causes, be they natural or supernatural. All that is needed are unintelligent, natural mechanisms operating in accord with the laws of physics.

Dembski claims that his law of conservation of specified information precludes the formation of complex systems through natural causes. But the universe we live in has lots of usable energy and is far from thermodynamical equilibrium. (At equilibrium both entropy and information would remain constant, on average.) The universe also contains many open-dissipative systems as subsystems. For example, our planet is warmed by a large hot star that provides plenty of usable energy, and the universe, not to mention our planet, is teeming with open systems that exploit this usable energy. Self-organization, resulting in decreases in the entropy of local, open systems, points clearly to the conclusion that we can indeed get CSI through self-organization resulting from unintelligent natural causes and that no invisible supernatural hand operating outside a system of purely natural causes is needed. Self-organization is indeed a great scientific bargain when compared with evidentially empty promissory notes concerning supernatural design from outside our natural universe.

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