Darwin Does Physics

John O. Campbell

This is a excerpt from the conclusion of the new book Darwin Does Physics. 

This account of the applicability of the Darwinian paradigm to the physical sciences is dependent on a context within universal Darwinism. Universal Darwinism may be most straightforwardly characterized as the fact that numerous theories across a broad range of science identify a Darwinian mechanism as responsible for the creation and evolution of their subject matters. While the adoption of this model within any one area of subject matter is remarkable, the fact that it has been widely documented throughout science makes it a coincidence demanding an explanation.

Within the social sciences Darwinian evolutionary theories are perhaps a consensus mechanism for explanations of cultural evolution. Most of the academic fields within the social sciences have a sub-school bearing the ‘evolutionary’ prefix including evolutionary psychology, evolutionary linguistics, evolutionary economics, evolutionary archaeology, etc..  

Even in the humanities Darwinian mechanisms are rife. Indeed a near consensus view within the philosophy of science considers science itself to be a Darwinian process; one which accumulates knowledge through an evolutionary process.

A powerful and compelling Darwinian/Bayesian model explains much of neuroscience. The Bayesian brain school views our mental models such as sight in terms of models that are constantly being updated with sensory information. The models which survive this Darwinian process are the ones we ‘see’.

In biology there is no scientific alternative to the Darwinian model. Of all the subjects making up the scientific enterprise only the physical sciences remain largely devoid of Darwinian explanation. Yet even here a few Darwinian theories have been proposed to explain physical phenomena at a fundamental level. 

I have described some of these Darwinian theories within the physical sciences and have suggested possible avenues by which this paradigm may contribute to the next generation of fundamental physical theories. 

Universal Darwinism is merely the observation that Darwinian explanations are common across all fields of science.  I have advocated a possible explanation for this coincidence involving information, inference and the accumulation of knowledge.

The most influential recent idea in physics may be that information is more fundamental than those entities such as matter and energy which physics has traditionally understood as most fundamental. The concept of information was first introduced to science by Claude Shannon in 1948. In a revolutionary tour de force he defined information and proposed information entropy as a measure of ignorance or uncertainty. Information entropy has subsequently been shown as equivalent to thermodynamic entropy which is at the heart of the second law and of all physics.

Significantly Shannon defined information in terms of probability assignments. Unless an entity has assigned probabilities to the outcomes of an event that entity cannot receive information about the event. Further this definition of entropy involves a probability distribution or a model of the event. 

Shannon’s great discovery was quickly followed by a re-birth of the mathematical field of Bayesian inference. Central to this field is Bayes’ theorem which describes the precise way in which a model should be updated when new information is received so that the model retains the greatest accuracy possible given the available information.

From this perspective information and entropy are not simple and may thus seem unlikely candidates to play a fundamental role in physical theories. In essence they involve one entity modelling another; one entity having some knowledge of an aspect of its environment and the ability to update this model as it receives new information. 

I propose that this complex knowledge entity, which includes information, probabilities, models and updating, be regarded as an inferential system which functions to accumulate knowledge. I have also argued that knowledge is a requirement for the existence of complexity and further that Darwinian processes are the physical implementation of inferential systems. Thus I attempt to explain the fact of universal Darwinism as due to nature’s dependence on the Darwinian process to accumulate the knowledge which is required for the existence of the complex entities studied by science.

Understanding Darwinian processes in this light moves us beyond its common ‘reproduction with selective retention’ definition and even the more sophisticated description by Dawkins and others in terms of ‘replicators’ and ‘vehicles’. In my view Darwinian processes invoke the mathematics of inference within reality. Thus they involve information, probability, models and updating. More generally they provide the mechanism by which reality is created and evolves.

The first intuition that information is at the basis of physics may be attributed to John Wheeler in about 1990. Since then it has proved remarkably productive, finding confirmation in areas such as the holographic principle, quantum information theory and the CFT/AdS duality. However within fundamental physics the consensus view concerning information is highly confused resulting in what E.T. Jaynes described as a standard of logic which would be considered a ‘psychiatric disorder’ in any other field of science.

Basic to this confusion is a failure to accept the fundamental finding that information must have a physical representation. The consensus view of quantum theory denies this and claims that the information of quantum theory is mathematical and has no physical representation outside of the human brain. This misunderstanding has resulted in endless attempts to link quantum phenomena to human consciousness. 

If an actual underlying physical representation of quantum information were discovered it would put an end to this nonsense but the scale at which this representation exists is likely far below the scale at which science is currently able to probe. 

This was also the case with biology at the beginning of the 20^th century when Mendelian ‘genetics’ was considered merely a calculational device and not to have any physical representation outside of human minds. Of course since then biological information has been found to have a physical representation in the form of DNA, a physical representation many orders of magnitude smaller than the biological phenotypes which it models. 

Since the discovery of DNA knowledge within biological science has exploded resulting in the theoretical paradigm of Neo-Darwinism. Biology is now understood as an inferential system where knowledge that models strategies for reproductive success is accumulated within organisms. In turn organisms themselves are constructed according to the specifications of this model.

Unfortunately physics may be stuck in a situation similar to that of biology before its revolution. If, as I have argued, the role of information within fundamental physics must be within the context of an inferential system, physics might profitably look to better understand Darwinian processes such as biology for analogies to guide its development. I have suggested a number of biological analogies which may be useful in this regard.

The Darwinian/Bayesian view portrays, existence on all levels of organization, as extremely unlikely. The single path to existence is through knowledge and knowledge may only be gained by experience in reality. This boot-strapping processes of evolving complexity appears to have quantum roots; at the limits of our empirical abilities appear a few miraculous mechanisms, the four fundamental forces, which allow one entity to experience or relate to another. Although the ability of one entity to experience another is wondrous it is also limited; only a scant description is ever possible.

Experience, by itself, is not sufficient to produce complexity. Knowledge must be extracted from that experience, knowledge in the form of strategies to avoid the harsh constraints of the second law of thermodynamics and knowledge to out-fox competitors with evolving strategies of their own. 

Bayesian inference provides the mathematical framework to describe this process of knowledge accumulation and nature has followed those guidelines in constructing Darwinian processes to create and evolve complex structures throughout reality.Given the basic abilities to experience and to learn from experience which we find at the level of fundamental physics, the complexities of atoms, chemistry and cosmology rapidly unfold. 

The evolution of life is a landmark in the cosmic evolutionary scenario. With life and the genome of organisms a second repository of knowledge was produced that further propelled the evolutionary search for complex forms. On our planet at least this process appears to have accelerated and the breakthrough of a biological knowledge repository has been rapidly followed by the formation of neural and cultural repositories.

This view provides a homey take on our individual predicaments. We are born into an historical context. On the basis of this initial state and our experiences in the world we try some things. We are seven billion people trying things which seem plausible to each of us given our experience. Our lives are experimental, they probe the boundaries of the unknown. Each of the many challenges we may face from feeding ourselves to being a better parent are largely met in this kind of experimental manner.

We share our identity as experimental beings with all other complex entities; this attribute does not make us special. What makes us special is the scope of our experiences. We are probing the bounds of our ignorance on many fronts from experiencing the evidence of the big bang to experiencing Shakespeare and we are accumulating knowledge at a rate, accelerating so rapidly, that some believe we are approaching a kind of knowledge singularity .  

As far as we know many aspects of our neural knowledge and almost all aspect of our cultural knowledge are unique and are possessed only by one species and only on planet earth. Although we are the product of natural processes we participate within nature at a spectacular level of complexity which may be unique. We are experiments which almost certainly, at least in exact detail, have never been attempted in the universe before.

There is a grandeur in this view which surpasses even that expressed by Darwin concerning the origin and evolution of species. We now have reason to believe that the same simple mechanisms which he first discovered underlie the creation and evolution of all complex entities found in nature and that our species is a distinct landmark within this process of universal evolution.

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Incompleteness of Quantum theory

John O. Campbell

Perhaps physicists more than other scientists have a penchant for thinking they are close to knowing practically everything that can be known. This obsession with arriving at the end of knowledge has been a constant under-current within the physics community almost since its inception as a science.

Nowhere has this hubris caused more problems than within quantum theory. On the one hand many physicists believe they are close to unveiling ‘the final theory’ or ‘the theory of everything’ on the other hand the consensus interpretation of quantum theory is a mishmash that, as Feynman noted, nobody understands. Trying to reconcile these polar attitudes towards our state of quantum knowledge has resulted in some laughable assertions. 

Most physicist believe that quantum theory is a complete theory and that there is little more to be added. The fact that we don’t understand what it means is often attributed to nature being weirder than we can imagine. Frequently it is claimed that we should not expect quantum theory to make sense, that it is not an explanation of nature only a method of calculating predictions. Following this line of reasoning some have cast quantum theory as a method of human reasoning (1), others have asserted that human consciousness is required in order for quantum processes to take place. As the Nobel laureate Eugene Wigner wrote (2):

It was not possible to formulate the laws (of quantum theory) in a fully consistent way without reference to consciousness.

I attribute these flights of fancy to the resistance amongst us all, but especially it seems amongst physicists, to recognize the huge extent of our ignorance. Rather than admit that our thinking about nature is confused we often conclude that nature acts in a confused manner.  Edwin Jaynes noted this glitch common to scientific thinking and dubbed it the ‘Mind Projection Fallacy’ (3):

it is essential to recognize that propositions at two different levels are involved. In physical prediction we are trying to describe the real world; in inference we are describing only our state of knowledge about the world. A philosopher would say that physical prediction operates at the ontological level, inference at the epistemological level. Failure to see the distinction between reality and our knowledge of reality puts us on the Royal Road to Confusion; this usually takes the form of the Mind Projection Fallacy

Jaynes reserved his most biting witticisms concerning the Mind Projection Fallacy for the consensus interpretation of quantum theory:

The current literature of quantum theory is saturated with the Mind Projection Fallacy. Many of us were first told, as undergraduates, about Bose and Fermi statistics by an argument like this: 

‘You and I cannot distinguish between the particles; therefore the particles behave differently than if we could.’ Or the mysteries of the uncertainty principle were explained to us thus: ‘The momentum of the particle is unknown; therefore it has a high kinetic energy.’ 

A standard of logic that would be considered a psychiatric disorder in other fields, is the accepted norm in quantum theory. But this is really a form of arrogance, as if one were claiming to control Nature by psychokinesis.

Despite its many short-comings quantum theory is the most accurate theory ever devised by science; it is used to make many solid predictions and thereby provides insight into nature. However the consensus interpretation of quantum theory has wrongly concluded from the theories numerous uncertainties and missing physical processes that nature is uncertain and is missing the usual physical mechanisms which allow the application of logic to a full explanation.

This situation remains the same today as it was almost a hundred years ago when Einstein pursued one of science’s great debates with other pioneers of quantum theory. His insistence on the incompleteness of quantum theory fell largely on deaf ears presumably due to an inability to accept the extent of our ignorance. It would seem the correct thing to do but the consensus chose instead to cover up the theories ‘incompleteness’ in a number of blatant denials and instead claimed that the theory was in fact complete.

We might wonder about the exact extent of scientific ignorance. One approach would be to imagine a contrasting model of the entire universe that contained complete scientific knowledge. This ultimate model would be able to predict the construction of the exact current state of the universe from its most fundamental entities. Scientific ignorance would then be the entropy of our current scientific models as compared to the complete knowledge of this ultimate model; the amount of information in bits required to bring our current scientific knowledge to completion. 

In estimating the extent of this entropy a couple of things may be worth considering. First we do not know what the fundamental entities making up the universe are. New ‘fundamental’ particles have been identified ever since the concept first arose within atomic theory and there is little reason to expect this to end any time soon. A new generation is expected if advanced theories such as super-symmetry or preons come to fruition.  In fact the current ‘fundamental’ sub-atomic particles are at the order of 10^-15 meters and we can expect new physics all the way down to the Planck scale at 10^-35 meters. This one arena of our complete ignorance is vast. Secondly and at a larger scale it is likely that complex macro processes at least partially analogous to biology and culture are common in the universe. A complete theory would be able to predict and describe all instances. 

While I will not attempt a numeric estimation of scientific ignorance it is clear that it is an enormous quantity and that we are vastly distant from any ultimate theory. It is a wonder that in the face of this immense ignorance the scant scientific knowledge we do have is sufficient to predict much of the universe we observe. This is likely due to our limited observational abilities at least as much as to the extent of our knowledge.

We can expect many uncertainties with quantum theory to be resolved and missing mechanisms found as science becomes better able to experimentally probe towards the Planck scale. However we should also expect that the current aspects of quantum theory leading to its many accurate and repeatable predictions will be incorporated within that full theory.

The concept of information and its transfer is essential to all of the axioms of quantum theory and yet the physical representation of this information is not described or identified. This must be considered a major hole in quantum theory as Zurek, building on the work of others, has conclusively demonstrated that there can be ‘no information without representation in a physical state’ (4). The consensus answer to this objection is to deny it and claim that quantum theory does not serve as a model for physical reality, it is only a calculational devise. In other words that the information of quantum theory does not have an independent existence outside of the human mind. 

Recent research seems to indicate that his consensus view is incorrect on theoretical grounds (5). It is also amusing to note that our proclivity to conclude that successful scientific models do not describe ‘real’ entities has a long history over which it has consistently proved wrong. 

Boltzmann attempted to base thermodynamics on the findings of atomic theory and the statistical kinetic motion of vast numbers of molecules. As atomic theory was not yet widely accepted he suffered many attacks from the pillars of the physics community which may have eventually influenced his decision to commit suicide. The preeminent German physics journal would not allow Boltzmann to refer to atoms as actual phenomena but only as convenient theoretical constructs. To facilitate this ruse he adopted Hertz’s theory that atoms were ‘Bilder’; merely models or pictures and were not ‘real’ (6).

This tendency to interpret effective models as only ‘calculational devices’ also arose in biology.  Mendel’s quantitative rules for predicting the frequency of parental characteristics which are inherited by their off-spring caused great excitement amongst biologists but many questions remained. There was much controversy whether these ‘genetic’ rules supported or challenged Darwin’s theory. On one thing there was a consensus; ‘genetics’ was not a physical process but merely a means of making calculations. The philosopher of science David Hull describes the situation (7):

As much as Bateson might disagree with Pearson and Weldon about the value of Mendelian genetics, he agreed with them that it was unscientific to postulate the existence of genes as material bodies. They were merely calculation devices.

The plain fact of the matter is that effective scientific models would not be effective unless they accurately described physical reality. The principle of naturalism at the foundations of the scientific world view tells us that there is nothing but physical reality. If our model is only mathematical and we are ignorant of the underlying physical situation which gives rise to the mathematics that does not mean there is no underlying physical situation, it only means that we have some remaining ignorance, that there is more to find out. 

We should not be ashamed of our ignorance; it is a noble state and vastly superior to a state of false knowledge.

If we accept that quantum states have physical forms just as real as genes we are left with the fundamental unanswered question: ‘In what form is the essential information of quantum theory physically recorded?’ 

Gerard t’Hooft has made one of very few attempts to answer this question with his cellular automata interpretation of quantum theory (8) where he speculates that the information of quantum theory is recorded within a physical medium near the Planck scale. He provides support for the idea that the rules of quantum mechanics emerge from a form of cellular automata where each bit of information is updated through simple rules depending only on the state of nearest neighbours.

This interpretation is analogous with the fact that the information of biology is recorded in a medium many order of magnitude smaller than the phenotype. Even though its small scale meant DNA was difficult for us to identify it did not rule out its physical existence. We should expect that with the many examples found in nature involving a duality between an informational model and a physical system the physical presence of the informational model will be more difficult to identify due to its smaller scale. In fact quantum physics may well be in an historical situation similar to the one in which biology found itself between Darwin’s publication of Origins of Species and the discovery almost a hundred years later of DNA, the physical form of biology’s informational model.

Bibliography

1. QBism: The frontier of quantum Bayesianism. Fuchs, C. 2010, Preprint.

2. Wigner, Eugene. Symmetries and Reflections: Scientific Essays. s.l. : MIT Press., 1970.

3. Jaynes, Edwin T. Clearing up the mysteries - the original goal. [book auth.] John Skillings. Maximum Entropy and Bayesian Methods. 1989.

4. Decoherence, einselection and the existential interpretation (the rough guide). Zurek, Wojciech H. 1998, Philosophic Transactions of the Royal Society; vol. 356 no. 1743, pp. 1793-1821.

5. Are quantum states real? Hardy, Lucien. 2013, International Journal of Modern Physics B.

6. Wikipedia. Ludwig Boltzman. Wikipedia. [Online] [Cited: June 7, 2014.] http://en.wikipedia.org/wiki/Ludwig_Boltzmann.

7. Hull, David L. Science as a Process: An Evolutionary Account of the Social and Conceptual Development of Science. Chicago and London : The University of Chicago Press, 1988.

8. The Cellular Automaton Interpretation of Quantum Mechanics. 't Hooft, Garard. s.l. : Arxiv preprint, 2014, Vols. arXiv:1405.1548 [quant-ph].