A controversial theory put forward by physicist Roger Penrose and anaesthesiologist Stuart Hameroff that posits consciousness to be a fundamentally quantum-mechanical phenomenon has been challenged by research looking at the role of gravity in the collapse of quantum wavefunctions. Based on results from an experiment done under Gran Sasso mountain in Italy, the new work concludes that Penrose’s and Hameroff’s Orchestrated Objective Reduction theory (Orch OR) is “highly implausible” when based on the simplest type of gravity-related wavefunction collapse – although they point out that more complex collapse models leave some wiggle room.
Many scientists regard consciousness as a global manifestation of individual calculations by the brain’s billions of neurons. Penrose and Hameroff instead argue that consciousness is based on the non-computational collapse of coherent quantum superpositions between cellular structures within neurons known as microtubules. They reckon that while the superpositions guide classical neuronal processes, it is the continual gravity-related collapse of the quantum states that gives rise to our sense of self-awareness.
As a physicist, I’ll have to say that random interactions between collapsing wavefunctions is not a feasible way to generate the conscious state we all know as self-awareness. Readers may be familiar with the speculative quantum concept known as observer-created reality, in which an observer causes the collapse of a quantum wave function into a specific state. Here, the researchers appear to posit the reverse process, in which an observer is caused by collapsing wave functions within the brain. The idea may have an imaginative appeal, but let’s be realistic, our consciousness is not the manifestation of random natural processes, no matter how such processes is embellished with esoteric concepts from modern physics.
In the latest work, Catalina Curceanu of the Frascati National Laboratory near Rome and colleagues assess the plausibility of Orch OR in the light of results from an experiment they set up to probe gravity’s possible role in wavefunction collapse. Standard quantum theory leaves open the question of what causes a state’s wavefunction to collapse, simply providing the probabilities of the system collapsing into one classical state or another and implying that the process is random. But several physicists over the years have attempted to identify a physical mechanism behind the process.
The researchers add that not all is lost for Orch OR. While they reckon that the theory seems implausible if based on the simplest wavefunction collapse model, it may become more plausible if a more sophisticated model can be developed – one, for example, that conserves energy (something not true of Diósi’s current model). “In future work,” they say, “we intend to develop such variants of the Diósi-Penrose collapse dynamics and then reexamine the tubulin superposition scenarios discussed above.”
See the complete article at Physics World.