A few years ago, deep in the Apennine mountains in Italy, a team of physicists searched for flashes of light that might suggest that human consciousness is the product of gravitational forces.
Just because they arrived empty-handed doesn’t mean we’re all meat computers with no free will; however, this makes finding an appropriate model explaining consciousness much more difficult.
If the idea of not having free will is uncomfortable, you are not alone. In the 1990s, Nobel laureate Roger Penrose and an anesthesiologist named Stuart Hameroff argued that the quantum properties of cellular structures called microtubules could introduce enough leeway for the brain to free itself from restrictions “one input, one output” of classical mechanics.
Although their hypothesis, called Orchestrated Objective Reduction (Orch OR), falls on the fringes of physics and biology, it is nevertheless comprehensive enough to provide researchers with predictions that can be studied scientifically.
“What I liked about this theory is that it is in principle testable, and I decided to look for evidence that could help confirm or refute it,” says physicist Catalina Curceanu from Laboratori Nazionali di Frascati in Italy.
Penrose and Hameroff’s concept might be testable, but it still relies on a mountain of assumptions about how physics and neurology work at a fundamental level.
The fundamental notion of quantum mechanics is that all particles exist as a range of possibilities unless they are somehow quantized by a measurement.
Exactly what this means is unclear, leading some to interpret the difference as a “collapse” of the undulating mist of maybes into a concrete absolute of harsh reality.
Equally appealing is the question of why a swarm of possible values should settle on a single measure.
An idea championed by Penrose and his colleague Lajos Diósi in the late 20th century suggested that the curvature of spacetime might favor some possibilities over others.
To put it another way, mass and its gravitational pull could somehow crush quantum flat waves.
Applying this hypothesis to competing quantum states of cellular material – namely tubulin that shuffles chemicals inside neurons – Penrose and Hameroff calculated how long it would take for quantum effects to translate into mechanisms that would affect consciousness.
Although their model stops short of explaining why you made the conscious choice to read this article, it shows how neurochemistry can deviate from classical computational operations towards something less restrictive.
Penrose and Diósi’s idea of gravitational collapse has already been tested by none other than Diósi himself. Their experiment at the Gran Sasso National Laboratory examined the simplest of collapse scenarios, finding no signs that the hypothesis was accurate.
In light of these findings, the team now asks how their previous results might affect Penrose and Hameroff’s Orch OR hypothesis.
Their critical analysis of the model suggests that at least one interpretation of the hypothesis can now be ruled out. Given what we know about quantum physics, the distribution of tubulin in our neurons, and the constraints imposed by Diósi’s previous experiments, gravity is extremely unlikely to pull on the strings of consciousness.
At least, not in this specific way.
“This is the first experimental investigation of the gravity-bound quantum collapse pillar of the Orch OR model of consciousness, which we hope will be followed by many more,” says Curceanu.
It’s hard to say exactly what that would mean if an investigation turned up a glimmer of evidence for Orch OR. Non-computational descriptions of consciousness are not only difficult to study; they are difficult to define. Even indisputable programs that echo human thought defy our efforts to spot examples of sensitivity, self-awareness, and free will.
Yet the idea that biological systems are too chaotic for delicate quantum behaviors to emerge has weakened in light of evidence that entanglement plays a role in functions such as navigation in birds.
Perhaps a flash of inspiration is all we need to set us on the path to understanding the physics of our very souls.
This research was published in Opinion on the physics of life.