PHYSICS VS. BIOPHYSICS

The idea prevails that physics is inadequate at describing the complexity of life emergent from chemistry, and that it must be supplemented by biophysics. Physicist Erwin Schrodinger, in his 1947 What is Life?, hypothesized there may yet be undiscovered laws of physics to explain how life could have arisen and developed despite limitations placed upon it like the second law of thermodynamics. Emergence is seen as the appearance of organic systems of increasing complexity whose wide variety of mechanisms is combined in such a way as to presumably render the physical sciences irrelevant given reductionist methodology. Reductionism emphasizes analysis of the parts, and is given to deduction along mathematical lines. Biologists are looking for mechanisms, nonetheless. To understand life deductively, to mathematize it, one must reduce it to its essentials. Ernst Mayr, in his 1982 The Growth of Biological Thought, describes this as essentialism, a reductionist methodology he decries as inappropriate for life, given the specialness and historicalness of its subject matter, and its enormous complexity. This illustrates the point. We witness now Stuart Newman who pushes for an extended synthesis of evolution to satisfy the untoward findings of the developmentalists and epigeneticists like himself who find genetics inadequate for explaining these findings. Newman even writes of biological physics, and appeals to chemo-mechanical forces behind development, neither of which he is very specific about. This is the consequence of specialization when cross-disciplinary pollination is called-for to resolve the contretemps. No biophysics is adequate for the task, even if there were such a thing. The rubric biphysics is used by biological specialists as shorthand for the statement, “I don’t understand physics.”

In the case of life, essentials are two: organic chemistry, and the chemical energy capture necessary for the covalent bonds of organic chemistry. Knowing the electrical characteristics of the organic chemistry of our biological clock, how it is wound-up and transmits power to the parts of its substance, we can deduce what it will take to slow that wind-down, and maintain those parts. To do this we must mathematize the essentials.

Every chemical reaction either takes energy or gives off energy. The generation of the covalent bonds of organic chemistry takes energy. This energy is captured in redox coupling, the efficiency of which is expressed as a ratio of amperes captured to amperes available for capture. The recharge rate of an organic biomass is determined by its size (in grams), the energy available, and the ability of the structure of the mass to capture (absorb and expend) energy from what is available. The duration of the structure, its size (increase, and decrease), replication, development, and the equilibration of energy through it that appears as motor activity, is directly related to the recharge rates of the structure and its parts. This is expressed in the version of Kleiber’s Law containing, in the exponent for biomass, the term metabolic efficiency, where that is the redox ratio of amperes spoken of in the first part of this paragraph.

The 1932 Kleiber’s Law is an equation that relates the recharge rate of the covalent bonds of organic biomass, to the size of the biomass. Originally limited to the study of biological energy in terms of heat, the exponent of biomass was argued to be 2/3 since this modeled the rate of heat loss of the biomass to unit of surface area in a circular or slightly ovoid shape. Things became more voluminous (radius to the third power) faster than their surface area (radius to the second power) increased. More massive things lost less heat per unit surface area than smaller things, and were taken to be more efficient at energy retention as a result. Two people who huddle together to avoid freezing increase collective mass faster than surface area exposed to the cold, and so are less likely to freeze than two people who remain separate. But Kleiber declared that the exponent was more likely 3/4 than 2/3, from his studies of the energetics of heat loss in mammals. The appropriate exponential value has long been contested.

In 1997 Geoffrey West et al. Science argued that the number 3/4 resulted from the increased ability of larger organisms, with hearts, to deliver nutrients to the cells. Vascular branching, the argument went, was fractal-like in nature, and this resulted in an extra Euclidean dimension, in effect. In this model the battery-like nature of the cell was taken to be that of a primary cell, where the energy needs of the cell were the result of the combustion/oxidation of nutrients within the cell, nutrients re-supplied by vascular flow more directly than by tidal delivery. The catabolic/oxidative, intracellular breakdown of the nutrients of these lucky cells was the denominator of the redox-coupling, metabolic efficiency (ME) ratio, with the generation of ATP in the numerator. This is the battery part of the cell, driven by redox activity.

The analogy of the cell as a primary battery contrasts with the view of it as a secondary cell, a rechargeable battery. Some chemical reactions within the cell, particularly those dealing with the generation of ATP in the mitochondrion (e.g., the hydrolysis and generation of NADH), are reversible. This means re-synthesis of NADH can take place without supplemental intra-cellular oxidation from delivered nutrients. The re-synthesis of NADH from NAD and H+within the mitochondrion’s inner membrane, can be affected by the delivery of chemical energy from neuronal discharge to the chemical synapse at the somatic structure. From this point, following the electrochemical activity of neurotransmitters upon key post-synaptic cells, charge is conducted to the individual cells’ gap junctions. At these junctions a salt bridge in an ion channel sees to the cellular capture of charge in reversed chemical processes. In this sense the cells of the organism are secondary cells. This involves a further increase in metabolic efficiency for the cell, with the numerator increasing while the denominator (intracellular, catabolic oxidation) remains constant. In the sense that this energy arises from the digestive-breakdown of organic molecules in the stomach of the organism in neuro-gastric coupling, the organism is a primary battery, while its cells are secondary batteries.

Since efficiency is measured against loss to heat, the exponent becomes then either (3ME-1)/3ME, or (4ME-1)/4ME, where ME is metabolic efficiency. In either case a graph of the equation using either exponent will resemble the other. For purposes of clarification, 3/4 will be taken to occur at 100% ME, and 2/3 at 89% ME. These values for ME are very unlikely, and not even characteristic of mechanical systems as in clocks, let alone chemical ones.

When a graph is made of the equation MR (metabolic recharge rate of covalent bonds) = W (biomass in grams) raised to the power (4ME-1)/4ME, with a different curve for each W, quite a different picture emerges than for the same equation using either 2/3 or 3/4 as the exponent. There seems to be a set of attractors causing all curves to merge at 25% ME and one gram, at which point fluctuations in MR are less drastic given slight changes in ME. What this announces is that thermodynamic tendencies for changes in biomass to temper swings in MR given changes in ME, that is, tendencies for MR equilibrium, pressure for biomass to approach one gram in size, and 25% efficiency. The energetics of organic biomass organization, for all biomass, are the determinant factors behind all aspects of biomass – from replication and development to activity. The picture reveals that the origins and morphogenesis of biomass to accomodate changes in ME, are primarily about metabolism and only secondarily about genetics. Metabolism includes replication where the latter is change in value for W to equilibrate perturbations in MR following from fluctuations in ME. The forces and pressures driving morphogenesis, relating reproduction to food availability, triggering mutation and variation in gene expression, explaining the pros and cons of longevity increase through caloric restriction, and exposing dieting as a bad weight loss technique, are modeled in the numbers. And much more.

None of these things are understandable using biophysics, where redox coupling is considered a small part of life ruled by genetics and winnowed by circumstance, where metabolism includes heat generation, and where chemical energy is thought to include ion currents and chemiosmosis. This is seen most profoundly in the understanding of biological energy extant in the field of the life sciences, with regard to energy and electricity. The 1902 hypothesis of Julius Bernstein, to the effect that a voltage would someday be measured across a neuron membrane, and that the voltage would be due to an ion concentration gradient, was an attempt to explain the electricity of the nervous system. Bernstein used the Nernst Equation to justify this hypothesis. The Nernst Equation, according to its author, Walther Nernst, was not about electrical pressure. It was a thermodynamic equation in which the term volt expressed entropic pressure calculated to cause two different solutions to mix when the barrier between them was removed. Volts were calculated, not measured.

Bernstein’s hypothesis was considered proven when, in the early 1940s, a voltage was measured across the cell membrane. The detection of the voltage did not prove it was due to an ion concentration gradient. This was assumed, however, and in subsequent years the hypothesis was expanded and became known as the ionic channel model of nerve impulse propagation, chemiosmosis, and the proton motive force. The idea and those who traffic in it have been awarded a Nobel Prize at least five times despite the idea’s lack of empirical or clinical import. The presentation of the theory as a fundamental of physiology is catechetical in nature, learned by beginning specialists as a basic, and then never returned to in practice since it lacks real-world relevance. This is the province of biophysics, and the yammering of the evo-devo sorts who invoke it to justify extended syntheses of evolution.

In fact the nature of electricity was not understood in its electrical and chemical bonding role, and its place in the periodic table of the elements, for twenty years after Bernstein’s hypothesis. Chemical energy was expressed in coulombs whose rate of flow was measured in amperes, a term universally accepted by physicists in 1906. This form of energy was quantized, that is, it occurred in discrete packets known as electrons, whose place in the atom and molecular bonding (ionic and covalent bonds), was still being refined and understood till at least the late 1940s, with the development of the transistor and understanding of semi-conduction.

The ionic channel model of nerve impulse propagation (from Bernstein’s unproven hypothesis founded on the arrogation of the subject matter of the Nernst equation for something it was not intended to model) was an attempt to account for the electricity of the nervous system without resort to electrons, whose properties as cathode rays were thought of as biologically irrelevant at the time. The ionic channel model was subsumed under the field of bioenergetics, and regarded as a necessary supplement to prosaic redox coupling whose simplicity was interpreted as inadequate for understanding vitalist complexity. Redox coupling was the movement of electrons from one chemical reaction to cause another. Bertil Hille Ionic Channels of Excitable Membrane, 1991] writes: “In this heroic time of what can be called classical biophysics (1935-1952) the membrane ionic theory of excitation was transformed from untested hypothesis to established fact…The story illustrates the tremendous power of purely electrical measurements in testing Bernstein’s membrane hypothesis.”

The problem was that biological, theoretical understanding of electricity was so insular and nineteenth century that there was no way that any conclusions drawn from the electrical measurements could be taken as valid. For example, Hille writes: “One can draw an analogy between Ohm’s law for electrical flow and the rule for flow of liquids in narrow tubes.” This is the pre-twentieth century view of electricity as a fluid, a view that was completely expunged from the physical sciences prior to what Hille calls the heroic time of classical biophysics. In 1980, in a Scientific American article, Pierre Morell and William T. Norton report in their essay “Myelin,” in all seriousness that “…the mechanism by which Myelin facilitates conduction has no exact analogy in electrical circuitry,” where this mechanism involved fluid electricity that did not rely upon electrons. Without an exact analogy to electrical circuitry, proof of this model, Hille avers, was based upon ‘purely electrical measurements.’ In the 1991 Principles of Neural Science [3rd edition, Koester, “Cell Membrane Voltages”, ed. Kandel, Jessel and Schwartz, and all subsequent editions] can be found ‘membrane equivalent circuits’ that have no analogy in electrical circuitry, but that use the equations and devices of electrical circuitry (capacitors and resistors) to explain the model. In his essay Koester points out in a footnote that Nernst voltages calculated, and electrical voltages measured, for potassium ions in a biological cell, when graphed, show two lines that diverge on either side of an intersection. For the biophysicist this intersection is proof that the two voltages are the same.

In his 1976 The Understanding of the Brain_, John Eccles, who, with Alan Hodgkin and Andrew Huxley, received a Nobel in 1963 for the ionic model of nerve impulse propagation, writes: "_The content of the axon has the consistency of jelly, and for most purposes you can substitute an appropriate salt solution without deteriorating impulse conduction by the fiber. For example Baker and Shaw were able to squeeze out the contents of the giant squid axon with an open end by a kind of microroller, leaving a collapsed, flattened axon that appeared destroyed. Yet when they reinflated it by an appropriate salt solution, a potassium salt, the fiber was restored and conducted well for hours." Here Eccles is claiming that the nerve’s electrical functioning is independent of the contents of the axon (a resistor in the membrane equivalent circuity), and is entirely dependent upon the nature of its surrounding fiber because it is the fiber that permits the flow of ionic currents.

That such currents can be detected and simulated with electrical equipment that functioned using electrons, as in the practice of patch clamping, does not seem to have stimulated speculation in any neuroscientist that maybe Nernst voltages and ion currents are not valid models for electromagnetism. Patch clamping is a micro-electric recording technique devised by Bert Sakmann to study the individual ion channel in a cell, for which he received a Nobel in 1991. Neither Sakmann nor anyone who came after him questioned that bioelectricity could function without electrons; and even though electrons had a profound affect on the flow of bioelectricity, so profound an affect that the idea bioelectricity involved electron movement, as in redox coupling, was the most sensible conclusion, one that would make bioelectricity concordant with physics. This is biophysics, and its lack of simplicity is befitting the subject matter of vitalist complexity and emergence.

The ionic model was embellished upon by Peter Mitchell, who received a Nobel in 1978 for chemiosmosis and what he termed proticity_. Mitchell equated ∆pH with electrical voltage, where a ∆pH of 3.5 was equated roughly with 210 mV, on the basis of Nernst calculations, not measurements, of voltage. Proof of the conflation of the two theoretical schemes was alleged to be found in the generation of heat when the ∆pH included the number 7, that is, when acid/base reactions were involved. In such reactions the chemical energy liberated by the formation of ionic bonds was taken as evidence for the validity of Nernst’s application to [heat] energy (thermodynamics), even though a ∆pH that did not include the number 7 did not result in the liberation of any energy even though Nernst thermodynamics still applied. Ionic bonds gave off energy, unlike the covalent bonds of organic chemistry, that require energy. The model of bioelectricity favored by Mitchell and the bioenergeticists, and propagated by Koester (_Principles of Neural Science, 1991), consequently defined electrical energy as being dependent upon the separation of charge through the breaking of ionic bonds, as if this were one way to store biological energy. This method for storing electrical energy is found nowhere in physics, and is used by no one to power anything. For the biophysicist this became a selling point, for it underlined the specialness of life.

Ion currents (as they became known) do not manifest any sort of induced magnetic field when they were said to be flowing, something never tested for by Bernstein or any life scientist that followed, despite that Helmholtz, in the early 1880s, used this affect (the Oersted Affect) to detect the nerve impulse in vivo, and get a solid estimate for the speed of the nerve impulse. This, if nothing else, is a clear indication that electromagnetism and ion currents driven by fluid dynamics, were entirely incommensurable. There is no excuse for perpetuation of Bernstein’s error after 1935, the beginning of the golden age of biophysics, according to Hille.

Mitchell and the bioenergeticists confused the quantization of chemical energy with the second law of thermodynamics. The idea persists today that the movement of protons and cations in an electrolytic solution is a special form of energy transmission that is characteristically biological and not involving electrons. This is biophysics. In physics the movement of the same cations and protons in an electrolytic fluid is R in V=IR, and I is expressed in amperes. Yet for the biophysicist the slight attraction of anions to the cathode, and cations to the anode, when a battery providing a voltage discharges into an electrolytic fluid, is a chemical energy storage device. The energy stored is defined by the mathematics of Nernst, and able to be tapped when the battery is turned off. But the slight concentrations of ions around the electrodes triggered by battery discharge, dissipate into the bulk solution from thermodynamic forces, as Walther Nerst figured, and not from electrical forces.

Biophysicists declare there is stored, biologically-usable and information-encoding energy from charge separation, but without ever having a battery causing it in the first place. Instead what is involved is a system of pumps, mechanisms whose functioning is widely acknowledged to be yet poorly understood. So R becomes I, and membrane permeability and impermeability become R and C in the membrane equivalent circuit. This circuit has no exact electrical analogy but it has been proven by studying the measurement of those things that bear no exact analogy to it. Without I as amperes, electrochemistry and redox functioning of cellular, organic batteries is ruled out. This makes the mathematization of life’s essentials impossible, and prolongs the perplexity at life’s complexity. Evo-devo will go nowhere until it gets the physics right.