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Roger Penrose has proposed a new physics of objective reduction: "OR," which appeals to a form
of quantum gravity to provide a useful description of fundamental processes at the quantum/classical borderline.
Within the OR scheme, we consider that consciousness occurs if an appropriately organized system is able to
develop and maintain quantum coherent superposition until a specific "objective" criterion (a threshold related to
quantum gravity) is reached; the coherent system then self-reduces (objective reduction: OR). We contend that thistype of objective self-collapse introduces non-computability, an essential feature of consciousness which
distinguishes our minds from classical computers. Each OR is taken as an instantaneous event-the climax of a
self-organizing process in fundamental spacetime-and a candidate for a conscious Whitehead "occasion of
experience." How could an OR process occur in the brain, be coupled to neural activities, and account for other
features of consciousness? We nominate a quantum computational OR process with the requisite characteristics to be occurring in cytoskeletal microtubules within the brain's neurons.
In this model, quantum-superposed states develop in microtubule subunit proteins ("tubulins") within
certain brain neurons, remain coherent, and recruit more superposed tubulins until a mass-time-energy threshold
(related to quantum gravity) is reached. At that point, self-collapse, or objective reduction (OR), abruptly occurs. Weequate the pre-reduction, coherent superposition ("quantum computing") phase with pre-conscious processes, and each instantaneous (and non-computable) OR, or self-collapse, with a discrete conscious event. Sequences of OR events give rise to a "stream" of consciousness. Microtubule-associated proteins can "tune" the quantum oscillations of the coherent superposed states; the OR is thus self-organized, or "orchestrated" ("Orch OR"). Each Orch OR event selects (non-computably) microtubule subunit states which regulate synaptic/neural functions using classical signaling.
The quantum gravity threshold for self-collapse is relevant to consciousness, according to our arguments,
because macroscopic superposed quantum states each have their own spacetime geometries.l-2 These geometries are also superposed, and in some way "separated," but when sufficiently separated, the superposition of spacetime geometries becomes significantly unstable and reduces to a single universe state. Quantum gravity determines the limits of the instability; we contend that the actual choice of state made by Nature is noncomputable. Thus each Orch OR event is a self-selection of spacetime geometry, coupled to the brain through microtubules and other biomolecules. If conscious experience is intimately connected with the very physics underlying spacetime structure, then Orch OR in microtubules indeed provides us with a completely new and uniquely promising perspective on the difficult problems of consciousness.
The Brain Is Not Computable
A leading neuroscientist says Kurzweil’s Singularity isn’t going to happen. Instead, humans will assimilate machines.
Miguel Nicolelis, a top neuroscientist at Duke University, says computers will never replicate the human brain and that the technological Singularity is “a bunch of hot air.”
“The brain is not computable and no engineering can reproduce it,” says Nicolelis, author of several pioneering papers on brain-machine interfaces.
The Singularity, of course, is that moment when a computer super-intelligence emerges and changes the world in ways beyond our comprehension.
Nicolelis calls that idea sheer bunk. “Downloads will never happen,” he said during remarks made at the annual meeting of the American Association for the Advancement of Science in Boston on Sunday. “There are a lot of people selling the idea that you can mimic the brain with a computer.”
But Nicolelis is in a camp that thinks that human consciousness (and if you believe in it, the soul) simply can’t be replicated in silicon. That’s because its most important features are the result of unpredictable, nonlinear interactions among billions of cells, Nicolelis says.
“You can’t predict whether the stock market will go up or down because you can’t compute it,” he says. “You could have all the computer chips ever in the world and you won’t create a consciousness.”
The neuroscientist, originally from Brazil, instead thinks that humans will increasingly subsume machines (an idea, incidentally, that’s also part of Kurzweil’s predictions).