Physics is no more the study of matter and material only. It is not just about weights and measures or machines and equipments or rockets and radars or even games and gadgetry. Though it is mathematical, logical, analytical, empirical and conceptual but lately it has also turned out to be mystical and intuitional. It is much more than cosmic pursuits and physical laws governing the Universe. Physical world is not the whole reality nor can it be fully understood without a reference to the mind. Mind complements the matter. Since matter and energy are interchangeable, conscience being a form of energy interfaces with matter. Therefore, physicists are peeping into the conscience itself which enables us to think about everything and anything around us. What features of brain should give rise to conscience is what we essentially want to know. In other words, we are looking for a missing link between neuroscience and physics.
Since Quantum Mechanics is currently the most fundamental and most powerful theory of matter with very solid foundations, one would obviously like to apply it to the working of grey matter inside the brain. In Quantum Mechanics, everything is described by a wave-function which is a mathematical description of any physical system in terms of position, time, momentum and spin. For instance, there is a wave-function for a particle going left and one for the particle going right. However, there is also a wave-function for a particle that goes both left and right. This may sound weird but it is not wrong. This is called superposition which means that the particle is neither towards left nor towards right but both until we make a measurement. After measurement we get to know if the particle has moved left or right and the wave-function collapses.
In his first book on this subject, titled The Emperor’s new Mind, the well-known Mathematical Physicist Roger Penrose speculates, that somewhere deep in the brain, cells are to be found of single quantum sensitivity. Microtubules, which are the cellular structures within neurons, are considered to be the suitable hosts for quantum behaviour because these may contain delocalised electrons which exhibit quantum behaviour. In that context, quantum mechanics can be significantly employed in the study of brain activity. For instance, all of us have experienced to be in two states of mind in many situations of life. This can be attributed to quantum property of superposition, according to which particles such as electrons can be in two or more states at once. If their corresponding wave functions are coherent, then both states could be the possible outcomes of a measurement. The intentions of an observer also affect the outcome of what is being observed even in the most blinded experiments. Though the working of our brain is much like a computer but not all conscious activities can be simulated on a computer. Our brain has also a non-computational character.
Penrose and his co-researcher Stuart Hameroff who is an American anaesthesiologist, assert that conscience is due to the non-computational collapse of coherent quantum superposition between microtubules. The results of at least two experiments one each from University of Alberta and Princeton University lending evidence in support of quantum processes operating within microtubules were announced at The Science of Consciousness conference in April of 2022 held at Tucson Arizona.
So far the most complete, and also the most easily falsifiable theory of quantum conscience is the OrchOR or orchestrated objective reduction theory. It is also called Penrose-Hameroff model. According to this model, there are collective dipole oscillations orchestrated by microtubules which entangle, compute, and terminate or collapse the wave-function thereby governing the neuronal functions. The collapse of wave-function happens when we smell a rose or taste a chocolate for instance. Metaphorically, it sounds more like music than computational physics.
A rudimentary understanding of the state of mind from a Quantum mechanical perspective is necessary to follow the new ideas about conscience. Quantum mechanics is fairly applicable to everything and there is also an aforesaid quantum theory about conscience though it is not yet fully approved. The main argument against quantum conscience is that quantum states in brain lose coherency before reaching a scale of length and time that could be useful for neural processing. The calculations of Max Tegmark, for instance, show that de-coherence occurs at pico-second timescales while no response of brain has ever been this much fast. To this, Penrose suggests that each quantum superposition has its own space-time curvature which when separated by more than one Planck length (which is of the order of 10^(-35) metre), becomes unstable and collapses. The OrchOR theory of Penrose suggests neither randomness nor algorithmic processing but instead a non-computable influence in geometry of space-time from which both mathematical understanding and, by later extension, conscience is also derived. This is indeed a huge new beginning.
Dr. Qudsia Gani, Assistant Professor, Dept. of Physics, Govt. Degree College, Pattan Baramulla J&K