Objective Reduction
Penrose then proposed that existing ideas on wave function collapse might only apply to situations where the quanta are the subject of measurement. He considered the case of quanta that are not the subject of measurements or interactions with the environment, but remain isolated, and proposed that these quanta may be subject to a different form of wave function collapse.
In this area, Penrose draws on both Einstein's general theory of relativity, and on his own notions about the possible structure of spacetime. General relativity states that spacetime is curved by massive objects. Penrose, in seeking to reconcile relativity and quantum theory, has suggested that at the very small scale this curved spacetime is not continuous, but constitutes a form of network.
Penrose postulates that each quantum superposition has its own piece of spacetime curvature. According to his theory, these different bits of spacetime curvature are separated from one another, and constitute blisters in spacetime. Penrose further proposes a limit to the size of this spacetime blister. This is the tiny Planck scale of (10−35 m). Above this size, Penrose suggests that spacetime can be viewed as continuous, and that gravity starts to exert its force on the spacetime blister. This is suggested to become unstable above the Planck scale, and to collapse so as to choose just one of the possible locations for the particle. Penrose calls this event objective reduction (OR), reduction being another word for wave function collapse.
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. However 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.
The threshold for Penrose OR is given by the indeterminacy principle E = ħ/t, where E is the gravitational self-energy or the degree of spacetime separation given by the superpositioned mass, ħ is the reduced Planck constant, and t is the time until OR occurs.
There is no existing evidence for Penrose's objective reduction, but the theory is considered to be testable, and plans are in hand to carry out a relevant experiment.
From the point of view of consciousness theory, an essential feature of Penrose's objective reduction is that the choice of states when objective reduction occurs is selected neither randomly, as are choices following measurement or decoherence, nor completely algorithmically. Rather, states are proposed to be selected by a "non-computable" influence embedded in the fundamental level of spacetime geometry at the Planck scale.
Penrose claimed that such information is Platonic, representing pure mathematical truth, aesthetic and ethical values. More than two thousand years ago, the Greek philosopher Plato had proposed such pure values and forms, but in an abstract realm. Penrose placed the Platonic realm at the Planck scale. This relates to Penrose's ideas concerning the three worlds: physical, mental, and the Platonic mathematical world. In his theory, the physical world can be seen as the external reality, the mental world as information processing in the brain and the Platonic world as the encryption, measurement, or geometry of fundamental spacetime that is claimed to support non-computational understanding.
Read more about this topic: Orchestrated Objective Reduction
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