An Integration of Integrated Information Theory with Fundamental Physics
aa r X i v : . [ q - b i o . O T ] J u l An Integration of Integrated Information Theory with FundamentalPhysics
Adam B. Barrett ∗ Sackler Centre for Consciousness Science and
Department of Informatics
University of Sussex, Brighton BN1 9QJ, UK[Published Feb. 4, 2014 in the
Consciousness Research specialty section of
Frontiers inPsychology , article no. 5(63).]
Abstract
To truly eliminate Cartesian ghosts from the science of consciousness, we must describe con-sciousness as an aspect of the physical. Integrated Information Theory states that consciousnessarises from intrinsic information generated by dynamical systems; however existing formulationsof this theory are not applicable to standard models of fundamental physical entities. Modernphysics has shown that fields are fundamental entities, and in particular that the electromagneticfield is fundamental. Here I hypothesize that consciousness arises from information intrinsic tofundamental fields. This hypothesis unites fundamental physics with what we know empiricallyabout the neuroscience underlying consciousness, and it bypasses the need to consider quantumeffects.
Introduction
The key question in consciousness science is: “Given that consciousness (i.e., subjective experience)exists, what are the physical and biological mechanisms underlying the generation of consciousness?”.From a basic property of our phenomenology, namely that conscious experiences are integratedrepresentations of large amounts of information, Integrated Information Theory (IIT) hypothesizesthat, at the most fundamental level of description, consciousness is integrated information, definedas information generated by a whole system, over and above its parts (Tononi, 2008). Further, giventhe private, non-externally observable nature of consciousness, IIT considers consciousness to bean intrinsic property of matter, as fundamental as mass, charge or energy. Thus, more precisely,IIT posits that consciousness is intrinsic integrated information, where by intrinsic information itis meant that which is independent of the frame of reference imposed by outside observers of thesystem. The quantity of consciousness generated by a system is the amount of intrinsic integratedinformation generated (Balduzzi and Tononi, 2008), whilst the qualities of that consciousness arise ∗ [email protected] Fundamental fields and consciousness
Contemporary physics postulates that “fields” are the fundamental physical ingredients of the uni-verse, with the more familiar quantum particles arising as the result of microscopic fluctuationspropagating across fields, see e.g., Oerter (2006) for a lay person’s account, or Coughlan et al. (2006)for an introduction for scientists. In theoretical terms, a field is an abstract mathematical entity,which assigns a mathematical object (e.g., scalar, vector) to every point in space and time. (Formallya field is a mapping F from the set S of points in spacetime to a scalar or vector field X , F : S → X .)So, in the simplest case, the field has a number associated with it at all points in space. At a verymicroscopic scale, ripples, i.e., small perturbations, move through this field of numbers, and obeythe laws of quantum mechanics. These ripples correspond to the particles that we are composedof, and there is precisely one fundamental field for each species of fundamental particle. At themore macroscopic level, gradients in field values across space give rise to forces acting on particles.The Earth’s gravitational field, or the electromagnetic field around a statically charged object, areexamples of this, and the classical (as opposed to quantum) description is a good approximation atthis spatial scale. However, both levels of description can be considered equally fundamental if thefield is fundamental, i.e., not some combination of other simpler fields. Note that the electromagnetic2 ass (GeV/ c ) Electric charge Strong charge Weak chargeLEPTONIC MATTER electron neutrino ( ν e ) < . × − ν µ ) < . × − µ ) 0.106 -1 No Yestau neutrino ( ν τ ) < . × − τ ) 1.78 -1 No Yes QUARK MATTER up (u) 0.002 2/3 Yes Yesdown (d) 0.005 -1/3 Yes Yescharm (c) 1.3 2/3 Yes Yesstrange (s) 0.1 -1/3 Yes Yestop (t) 173 2/3 Yes Yesbottom (b) 4.2 -1/3 Yes Yes
BOSONSElectromagnetic force: photon ( γ ) 0 0 No No Strong force: gluon (g) 0 0 Yes No
Weak force: W −
80 -1 No No W +
80 1 No NoZ 91 0 No No
Gravity: graviton ∗ Higgs mechanism:
Higgs (H) 126 0 No YesTable 1: Table of the fields/particles that are considered fundamental. Familiar matter arises fromleptons and quarks, while the forces of nature arise from interactions of matter with “carrier” bosons.Mass is given in giga electron volts per speed of light squared (Gev/ c ≈ × − kg). Electric chargeis in standard units relative to minus the charge of the electron, i.e., one unit equals 1 . × − Coulombs. A description of the group theoretic strong and weak charges is beyond the scope ofthis article, but the table shows which fields have strong and weak charges. *The gravity fieldis considered fundamental and is well-studied, but the gravity particle (graviton) has not to dateexplicitly been observed; at quantum (i.e., very microscopic) spatial scales, a consistent set of fieldequations for gravity have yet to be constructed. 3nd gravitational fields are both examples of fundamental fields, with the corresponding fundamen-tal particles being the photon and the graviton. Particles are divided up into matter particles andforce-carrying particles, but all types of particle have associated fields; all the forces of nature canbe described by field theories which model interactions, i.e., exchanges of energy, between fields.See Table 1 for a list of fields/particles that are considered fundamental according to this so-called“Standard Model” of particle physics.To be consistent with modern theoretical physics, a theory of consciousness that considers con-sciousness to be a fundamental attribute of matter must describe how consciousness manifests itselfin the behavior of either fundamental fields or quantum particles. Since we know that the brain gen-erates electric fields with a rich spatiotemporal structure, and that, for the main part, informationprocessing in the brain is carried out by electrical signaling between neurons operating mostly inthe classical (as opposed to quantum) regime (Koch and Hepp, 2006), empirical evidence favors theformer. Thus, on the view that consciousness is a fundamental attribute of matter, it must be thestructure and/or dynamics of the electromagnetic field (which is an example of a fundamental field)that is fundamentally the generator of brain-based consciousness.Once one ascribes electromagnetic fields with the potential to generate consciousness, it is naturalto ask whether other fields might also have the potential to generate consciousness. According tomodern physics, there was a symmetry between all fields at the origin of the universe, although thesesymmetries were broken as the universe began to cool (Georgi and Glashow, 1974; see Hawking,2011 for a lay-person’s account). It could be argued by Occam’s razor that it makes more sense toposit that potential for consciousness existed at the outset, and hence potential for consciousness isa property of all fields, than that it emerged only during symmetry breaking. However, in practice,it is unlikely that any complex consciousness could exist in any field other than the electromagneticfield, for reasons to do with the physics and chemistry of the electromagnetic field compared withother fields. Considering the four forces: strong, weak, electromagnetic and gravitational, the strongand weak forces don’t propagate over distances much larger than the width of the nucleus of anatom, and gravity alone cannot generate complex structures by virtue of being solely attractive;in contrast, the electromagnetic field can propagate over macroscopic scales, is both repulsive andattractive, and is fundamentally what enables non-trivial chemistry and biology. Considering fieldsassociated with matter, these in general do not have any undulations at spatial scales larger thanthe quantum scale; the non-trivial structures in these fields are essentially just the ripples associatedwith the familiar quantum matter particles, i.e., electrons and quarks, and various “exotic” particlesdetectable in particle physics experiments (see Table 1). Finally, the recently discovered Higgs fieldhas essentially a uniform structure; quantum interactions exist between the Higgs field and many ofthe other fields, and this is fundamentally the origin of mass in the universe (see e.g., Coughlan etal., 2006; Oerter, 2006). Thus, the physics of the electromagnetic field uniquely lends itself to thegeneration of complex structures.
The Field Integrated Information Hypothesis
Given the above, I propose that the principal conceptual postulates of IIT should be restated asfollows. Consciousness arises from information intrinsic to the configuration of a fundamental field.The amount of consciousness generated by a patch of field is the amount of integrated informationintrinsic to it. When a patch of field generates a large quantity of intrinsic integrated information,4athematically there is a high-dimensional informational structure associated with it (Tononi, 2008;Balduzzi and Tononi, 2009). The geometrical and topological details of this structure determinethe contents of consciousness. The task now is to correctly mathematically characterize intrinsicintegrated information, and construct equations to measure it.A true measure of intrinsic integrated information must be frame invariant, just like any funda-mental quantity in physics. That is, it must be independent of the point of view of the observer:independent of the units used to quantify distance or time, independent of which direction is up, andindependent of the position of the origin of the coordinate system; and also independent of the scaleused for quantifying charge, or field strength.The “Φ” measures put forth by existing formulations of IIT (Balduzzi and Tononi, 2008; Barrettand Seth, 2011) are not applicable to fields because they require a system with discrete elements, andfields are continuous in space. One could ask, however, whether a perspective on a system in terms ofdiscrete elements could actually be equivalent to an intrinsic field-based perspective, thus obviatingthe need for a field-based measure. To see explicitly that this is not the case, let us revisit thephotodiode, which, according to the existing theory (Tononi, 2008), has 1 bit of intrinsic informationby virtue of having two states, on or off. There is a wire inside the photodiode, and the electronsinside the wire are all individually fluctuating amongst many different states. The electromagneticfield generated by the diode, and the circuit to which it is connected has two stable configurationsfor as long as the circuit is connected. But other more general configurations for an electromagneticfield are ruled out by each of these states. Considering the system at this level of description yields adistinct perspective, and would lead one to deduce that the amount of information generated by thesystem’s states is some quantity other than 1 bit. Thus the field-based perspective is not equivalentto the observer-dependent discrete perspective.The idea here is that a formula should be obtained that could in theory be applied universallyto explore the intrinsic information in any patch of spacetime, without requiring an observer to doany modeling, i.e., one would just measure field values in as fine a graining as possible to get thebest possible approximations to the intrinsic informational structure. Only a formula in continuousspace and time would allow this. If a discrete formula were to be applied, there would always bethe possibility of encountering an informational structure on a finer scale than that of the formula.(Unless the graining required by the formula were the Planck scale, i.e., the scale of the hypothesizedsuperstring, on which continuous models of physics break down; however there do not exist complexstructures at that scale.) In practice however, observations of systems are necessarily discrete, so dis-crete approximations to a continuous formula could be useful for empirical application. See Balduzzi(2012) for some recent work on the information-theoretic structure of distributed measurements.We don’t yet know how to properly calculate intrinsic information, so must remain agnostic onthe precise amount of intrinsic integrated information generated by photodiodes, or of anything.However, the failure of existing approaches does not rule out the construction in the future of asuccessful formula. While it is beyond the scope of this present paper to make a serious attempt atsolving this problem, I speculate that a formula in terms of thermodynamic entropy as opposed toShannon entropy might be more likely to succeed, as the former is inherently an intrinsic property,whereas the latter was constructed for the purpose of describing an external observer’s knowledge ofa system (Floridi, 2009, 2010; Gamez, 2011; Beaton and Aleksander, 2012).5 ntegrated Information Theory and panpsychism
Searle (2013) criticizes IIT for its stance that integrated information always produces consciousness,stating that this ludicrously ascribes consciousness to all kinds of everyday objects and would meanthat consciousness is “spread thinly like a jam across the universe”. Koch and Tononi (2013) counterthat only “local maxima” of integrated information exist (over spatial and temporal scales): “myconsciousness, your consciousness, but nothing in between”. If local maxima of intrinsic integrated in-formation in field configurations always generate consciousness, then there must be minute amounts,say “germs”, of consciousness all over the universe, even though there would be no superordinateconsciousness amongst groups of people. Thus, IIT and the FIIH do imply a form of panpsychism.However, the phenomenology assigned to an isolated electron in a vacuum, or even a tree, whichhas no complex electromagnetic field, would be very minimal. Since the only consciousness we canbe certain of is our own, the positing by integrated information theories of germs of consciousnesseverywhere is no reason to dismiss them. A theory should stand or fall on whether or not it canelegantly and empirically describe human consciousness.For those uncomfortable with subscribing to a panpsychist theory, a possible way round theproblem is to assign an attribute “potential consciousness” to matter at the most fundamental level.Then, the quantity of potential consciousness is simply the quantity of integrated intrinsic informa-tion. But only when there is a large amount of intrinsic integrated information with a sufficientlyrich structure to be worthy of being compared to a typical healthy adult human waking consciousmoment, should we say that the integrated information has “actual consciousness” associated withit. A line could thus be drawn somewhere between the potential consciousness of an isolated electronin a vacuum and the actual consciousness generated by my brain as I write this article. The problemwith such a distinction however is that potential consciousness would still be assigned phenomenalcontent, so it is perhaps more elegant to just use a single term “consciousness” for the whole spec-trum of integrated information. On the other hand, since consciousness is defined by some as anymental content, but by others as only self-reflective mental content, there is no single terminologythat appeals to everybody. The key point, irrespective of the precise definition of consciousness,is that on the theory discussed here, intrinsic integrated information is what underlies subjectiveexperience at the most fundamental level of description. Alternatively, one could further imaginedifferent lines being drawn for different purposes. For example, a threshold of conscious awarenessabove which surgery cannot be performed; or thresholds at which various people are comfortableeating animals.
Relation to previous electromagnetic field theories of consciousness
There have been several other theories of consciousness put forward that identify consciousness withvarious types or configurations of fields, see Pockett (2013) for a review. Notably, Pockett’s elec-tromagnetic field theory (EMT) of consciousness (Pockett, 2000, 2011, 2012) posits that “consciousperceptions (and sensations, inasmuch as they can be said to have independent existence) are iden-tical with certain spatiotemporal electromagnetic patterns generated by the normal functioning ofwaking mammalian brains” (Pockett, 2013). In the most recent formulation of this theory, the keyfeature of field patterns underlying consciousness is the presence of a neutral region in the middle ofa radial pattern. This hypothesis was motivated by the observation that such field patterns appear6uring recurrent cortical activity, (with the neutral region in layer 4), and the empirical associationof consciousness with recurrent processing (Pockett, 2012).A problem common to previous field theories of consciousness (Libet, 1994; Pockett, 2000, 2013;McFadden, 2002) is that they claim that cutting outgoing neural connections from a slab of cortexthat generates a conscious experience will not affect the ability to report that conscious experience.EMT argues that the electromagnetic field within such an isolated hypothetical slab would stillpropagate through space and enable communication between the conscious field generated by theslab and the spatially contiguous larger conscious mental field. This is not however compatiblewith the laws of physics. Any cutting of synapses to or from regions of cortex that are generatingconsciousness will alter the field, and will therefore alter the conscious experience. There is noelectromagnetic field residing in the brain other than that generated specifically by all of the neuraland chemical activity. And it does not make sense to talk of the brain’s electromagnetic field and itsfiring neurons and synapses as being able to exist independently of each other. On the theory putforward here, neurons can be considered the scaffolding that enable very complex electromagneticfield configurations to be sustained. As far as describing the mechanisms of perception and cognitionthat generate the specific contents of consciousness in any given scenario, the current paradigm ofassociating it with neural activity is of course the only valid and useful level of description. However,in terms of explaining more fundamentally how matter gives rise to consciousness, a description interms of fields would be much more elegant than a description in terms of the complex entities thatare neurons.Another shortcoming of previous field theories of consciousness is that none of them relate physicalproperties of proposed correlates of consciousness to properties of phenomenology, i.e., they do notposit “explanatory correlates of consciousness” (Seth, 2009). The FIIH raises for the first time thepossibility of constructing a field theory of consciousness that can account for a fundamental aspectof phenomenology, namely that conscious experiences are integrated representations of large amountsof information.
Discussion
In this paper I have hypothesized that, at the most fundamental level of description, human con-sciousness arises from information intrinsic to the complex electromagnetic fields generated by thebrain. This “FIIH” builds on the axioms of IIT, namely that consciousness is integrated informa-tion, and that consciousness is an intrinsic and fundamental property of matter analogous to mass orcharge. However, it also implies that a new mathematical formalism is required to properly quantifyintrinsic integrated information, since electromagnetic fields are continuous in space, and existing“Φ”-type measures of integrated information are applicable only to discrete systems (which requirean observer dependent perspective). The idea that consciousness can be identified with certain spa-tiotemporal electromagnetic patterns has been previously put forward in other electromagnetic fieldtheories of consciousness. But by suggesting that integrated information is the key factor, the theoryhere connects, for the first time, such electromagnetic field theories of consciousness to basic aspectsof phenomenology.The hypothesis is admittedly rather speculative, and any proposed mathematical formula forconscious level in terms of information intrinsic to an electromagnetic field will be difficult to testdirectly, simply because we do not have the technological tools or the computational resources to7ecord in full detail the three-dimensional electromagnetic field structure generated by the brain.Rather, this can only be sampled at a spatial scale that is sparse compared to the finest scale ofits undulations. However, there is a strong case to be made that the theoretical development of theideas presented here has substantial value. Theories in physics have been vigorously pursued fortheir logic and beauty, in the absence of imminent direct experimental tests. For example, there is avast amount of work being conducted on string theory; there, rather than experimental verification,the goal is an elegant explanation of our existing empirical knowledge of particle physics and gravity.If there already existed several analogous theories of consciousness, then one could argue that itwould not be useful to add to the speculation. However, there is as yet no compellingly believableset of equations for describing, fundamentally, how consciousness is generated. IIT has potentialin this direction, but a major step forward for the theory would be a truly plausible formula forintrinsic information applicable to fundamental physical entities. The FIIH provides a conceptualstarting point for achieving this. All this is not to say that such a theory will aid understanding ofall aspects of consciousness; indeed the multi-faceted nature of consciousness requires descriptions atmany different levels. Non-reductionist frameworks are required to understand the complexity of thebiological machinery that enables the brain to do any kind of information processing, conscious orunconscious, and to understand the differences between conscious and unconscious cognitive processesneural dynamics and behavior must necessarily be modeled at multiple levels of description.Finally, any theory can potentially indirectly make predictions. Indeed IIT has already inspiredheuristic measures of information integration/complexity that have been successfully applied torecorded electrophysiological data and are able to distinguish the waking state from diverse uncon-scious states, i.e., sleep and anaesthesia under various anaesthetics (Massimini et al., 2005; Ferrarelliet al., 2010; Casali et al., 2013). The results are in broad agreement with the predictions of IITand provide encouragement for further theoretical work on the relationship between information in-tegration and consciousness. Theories built from the FIIH could make new and distinct predictionsabout the types of structural and/or functional neuronal architectures that are capable of generatingconsciousness; and new theory can only further inform the quest for ever more reliable measures ofconsciousness that can be applied to observable brain variables.
Acknowledgements
I thank Emily Lydgate and Anil Seth for invaluable discussions during the writing of this paper, andDaniel Bor and David Gamez for very useful comments on draft manuscripts. ABB is funded byEPSRC grant EP/L005131/1.
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