Presentation on theme: "Cognitive Computing 2013 Consciousness and Computation 7. ORCHESTRATED OBJECTIVE REDUCTION (PENROSE) Mark Bishop."— Presentation transcript:
Cognitive Computing 2013 Consciousness and Computation 7. ORCHESTRATED OBJECTIVE REDUCTION (PENROSE) Mark Bishop
01/04/2014(c) Bishop: Consciousness and Cognition2 Monism, mentalism and qualia Monism: the doctrine which refers all phenomena to a single ultimate constituent or agent. Materialistic monism: mind is explained by and resolved into matter. Neutral monism: matter, mind, and their phenomena are manifestations or modifications of one substance - like the substance of Spinoza - which is capable of an objective and subjective aspect. Idealistic monism / mentalism: matter and its phenomena explained as a modification of mind; qualia provide the fundamental component of reality.
01/04/2014(c) Bishop: Consciousness and Cognition3 A.N. Whitehead, Process and Reality A.N. Whitehead (& Leibniz) support a idealist monist / mentalist framework such that systems ordinarily considered physical are constructed from mental entities. The experience has a vector character, a common measure of intensity, and specific forms of feelings that convey that intensity. If we substitute the term energy for the conception of quantitative emotional intensity and the term form of energy for the concept of specific form of feeling, and remember that in physics vector means definite transmission from elsewhere, we see that this metaphysical description of the simplest elements in the constitution ofactual entities agrees absolutely with the general principles according to which the notions of modern physics framed. Whitehead, Process & Reality, 116.
Occasions of experience Whitehead thus describes the ultimate concrete entities of the universe as being: actual occasions of experience … each bearing a quality akin to feeling. And hence broadly subscribes to a panpsychist concept ofexperience where even a temporal event in the career of an electron has a kind of proto-mentality … … a particular spatio-temporal experience such that it experiences relationships with the world around as vectored emotion/experience … … albeit Whitehead diverts from a simple panpsychism as the discrete occasions of experience have been related to quantum state reductions (cf. Hammeroff). 01/04/2014(c) Bishop: Consciousness and Cognition4
01/04/2014(c) Bishop: Consciousness and Cognition5 The Penrose-Hameroff Hypothesis, (PHH) P 1 : Conscious thought is essentially non-computable Echoing results on non-computability from Godel, Turing et al., Penrose claims that mathematical understanding cannot be encapsulated by a set of rules. And that this provides a clue as to the processes that must instantiate it. P 2 : Objective Reduction defines: a type of quantum [self] reduction … collapse of superposed quantum states to one macroscopic state … that is an emergent feature of some quantum systems It is an objective feature of the quantum system. Such self-reduction is a non-computable process. Quantum Self-Reduction, (contra Reduction; Subjective Reduction), defines a unique occasion of experience, a conscious instant Although theoretically panpsychist, at ten million years the period of self-reduction in a single electron is longer than the time modern man [homo sapiens sapiens] has walked on earth. P 3 : The provision of quantum Objective Reduction in the brain lies within the Microtubule cytoskeleton of the neuron.
01/04/2014(c) Bishop: Consciousness and Cognition6 Scope of the PHH The Penrose-Hameroff Hypothesis targets firmly held core theory in three distinct disciplines: P 1 : logic, computability and artificial intelligence; P 2 : quantum gravity :- the union of general relativity andquantum mechanics; P 3 : the biology of the brain. And as such it is perhaps unsurprising that the theory has attracted strong critical comment from all three disciplines…
01/04/2014(c) Bishop: Consciousness and Cognition7 P 1 - The argument from non- computability Penroses argument derives from Godels theorems and is concerned with how mathematicians arrive at unassailable demonstrations of mathematical proof. See also J.R. Lucas for a subtly different, (more direct), critique of computational theories of human mind (and behaviour) based on Godels theorems. Lucas, J.R., (1961), Minds, Machines and Godel, Philosophy, XXXVI, pp. 112-127. Penrose purports to demonstrate that, Human mathematicians are not using a knowably sound argument to ascertain mathematical truth, (Shadows, pp. 76; also Bishop, lectures on NORMA).
01/04/2014(c) Bishop: Consciousness and Cognition8 P 2 – Quantum Objective Reduction: quantum mechanics A quantum system which remains isolated from its environment behaves as a wave of possibilities and exists as a complex-number valued super- position of many possible quantum states. The behaviour of such wave like objects can be described by a state vector which evolves deterministically according to the Schrodinger equation, U. In a transition known as wave function collapse, (quantum state reduction, R), such quantum super-positions lead to non super-posed stable macro- structures, one of the many possible eigenstates of the quantum operator. According to the most conventional [standard] interpretation of quantum mechanics - the Copenhagen interpretation - the evolution of the eigenstate is entirely random. Which led Einstein to famously remark, … you believe in a God that plays dice!
01/04/2014(c) Bishop: Consciousness and Cognition9 Some possible forms of quantum reduction (a) Perhaps coherent super-positions persist until a Random Reduction, R, process occurs? (b) Or perhaps coherent super-positions persist until an act of observation occurs, Subjective Reduction, SR? Schrodingers cat :- macroscopic objects, if unobserved, may remain in super- position. (c) Or perhaps coherent super-positions persist indefinitely over time in themultiple universes? An idea the physicist Hugh Everett - father of Mark Everett, singer and guitarist with the rock band, EELS – famously developed working with his thesis advisor, John Wheeler in 1957. [NB. Almost astonishingly this is currently considered one of the mainstream interpretations of quantum physics].
01/04/2014(c) Bishop: Consciousness and Cognition10 (d) Penrose new physics of Objective Reduction (OR) Alternatively Penrose has argued that the reduction is defined by a deeper, non-computational processes, that cannot be calculated algorithmically. Since in most cases reduction is entangled with random effects from the environment, Penrose suggests R is actually a close approximation to a non-computable Objective Reduction, OR Hence usually OR is virtually distinguishable from R. However when the quantum system remains coherent and isolated from the environment, then it become possible for its state to collapse spontaneously, in accordance with the objective scheme, OR, that Penrose suggests behaves in fundamentally non-computable ways. Moreover OR involves the geometry of the universe at its deepest level.
01/04/2014(c) Bishop: Consciousness and Cognition11 Consciousness and Objective Reduction In OR a conscious event occurs if an organised quantum system that is able to isolate and sustain super-position until its specific quantum gravity threshold for space-time separation is met; The quantum system then [non-computably] self reduces. For consciousness to occur such self–reduction - as opposed to random reduction from the environment - is essential. Such self-reduction is instantaneous and has been suggested [by Stuart Hameroff] as a candidate for Whiteheads, occasion of experience; … the fundamental component of a reality.
01/04/2014(c) Bishop: Consciousness and Cognition12 Objective Reduction and consciousness Only large collections of particles acting coherently in a single macroscopic quantum state could sustain coherent superposition in a time frame long enough to reach OR threshold and brief enough to be relevant to consciousness The OR process must be at least transiently isolated from the environment long enough for OR to take place Quantum entanglement with the environment would result in random (not non-computable) processes to take place. Cascades of discrete ORs give rise to a perceptual unity and an unbroken stream of consciousness.
01/04/2014(c) Bishop: Consciousness and Cognition13 On the super-position of space- time 4D reality (space-time) is a 3D space plus a 1D time. This 4D space-time is slightly curved according to Einsteins general theory of relativity, in a way which encodes the gravitational fields of all mass- densities. Consider super-posed quantum states in which the relative mass distributions differ significantly from each other. Such states will have different space-time geometries and the super-posed state will involve a quantum super-position of these differing space-times geometries. There is currently no accepted way of dealing with this, however many authors (inc. Penrose), have made tentative suggestions. There is no existing evidence for Penrose's objective reduction, but the theory is considered to be testable, and [since 2003] plans have been in hand to carry out a relevant experiment.
01/04/2014(c) Bishop: Consciousness and Cognition14 Objective Reduction: a speculation Such quantum superposition of space- times forces a bifurcation of space- time and is inherently unstable with a life time given by the product of the temporal and the spatial separation, after which it will reduce to a single state, being one or other of the original superposed states. The future state is proposed to be selected by a "non-computable" influence embedded in the fundamental level of space-time geometry at the Planck scale; Penrose links this influence to a deep Platonic reality, representing pure mathematical truth, aesthetic and ethical values.
01/04/2014(c) Bishop: Consciousness and Cognition15 OR and neural proccessing An important feature of Penrose's objective reduction is that the time to collapse is a function of the mass/energy of the object undergoing collapse. Thus the greater the superposition, the faster it will undergo OR, and vice versa. Tiny superpositions, e.g. an electron separated from itself, if isolated, would require 10 million years to reach OR threshold. An isolated one kilogram object (e.g. Schrödinger's cat) would reach OR threshold in only 10 37 seconds. Objects somewhere between the scale of an electron and the scale of a cat could collapse within a timescale that was relevant to neural processing.
P 3 – Where are non-computable processes in the brain? Properties of the brain required for quantum coherent super-position, OR and relevant to consciousness might include: high prevalence; functional importance (in say, neuron firing); periodic crystaline structure; ability to transiently isolate from environment; functionally coupled to quantum events cylindrical – possible wave guide suitable for information processing. Stuart Hameroff has suggested that neuronal cytoskelton microtubules appear to fulfil all the above criteria. 01/04/2014(c) Bishop: Consciousness and Cognition16
01/04/2014(c) Bishop: Consciousness and Cognition17 The Neuron
Microtubules Microtubules form the cytoskeleton of neuron. Microtubules sub-units (tubulins) are hypothesized to be a means of harnessing appropriate quantum effects. Microtubule Associated Protein, MAP, form [weighted] linkages between microtubules to form cytoskeletal lattice networks. These networks have information processing capabilities in their own right and also may influence macroscopic classical neuronal behaviour; syntapes; cell firing etc. 01/04/2014(c) Bishop: Consciousness and Cognition18
01/04/2014(c) Bishop: Consciousness and Cognition19 Orchestrated Objective Reduction, (Orch-OR) It is hypothesized that microtubule associated protein, MAP, attachment sites orchestrate, (or tune), quantum oscillations in the microtubule lattice and regulate self-collapse, (Objective Reduction). Such orchestrated self-collapse is a time irreversible process, creating an instantaneous now event. Sequences of such events form the stream of consciousness. Orchestrated Objective Reduction thus define self-selecting processes in the fundamental space-time geometry of the universe and if, as Whitehead and others suggest, experience is a fundamental component of space-time, then Orchestrated-OR may well begin to address the hard problem of consciousness.
01/04/2014(c) Bishop: Consciousness and Cognition20 Against Penrose theory The temperature of the brain is too high for quantum events. Cf. Surface water at Micro-Tubule is ordered and may isolate MTs to enable suitable quantum coherence. High temperature superconductivity research is constantly raising the temperature upwards towards room. Gödel was talking about consistency of mathematical systems not mathematical understanding. But Penrose generalises the Godel/Turing argument. Quantum mechanics is not complete; OR at best is speculation, at worst is just plain wrong. In an online critique of Penrose in Psyche, few criticised his physics. Biologists nearly unanimous in their disagreement of there being any quantum effects observeable in neuron behaviour. Poor quality of alternative biological theories of consciousness; Experiments still ongoing.