Classical Networks Can Behave Like Quantum Systems, Raising Doubts About Quantum Biology

For years, Princeton chemist Gregory Scholes has championed the idea that living cells harness quantum physics on a tiny scale. He is now reversing that position. Across several papers released over the last three years, Scholes and his team have demonstrated that elaborate systems of ordinary objects can give rise to effects that match quantum behavior in their mathematical description. The states these systems generate are not genuinely quantum; they are merely “quantumlike.”

For decades, scientists have hunted for signs of quantum behavior in living systems, without success. Life operates across enormous distances, from the globe-spanning layer of living matter down to the tiny building blocks inside cells. At its tiniest level, biology never quite reaches the quantum realm, where particles behave like waves, link together, and sit in several states at once. Still, researchers keep searching for paths by which living things could bring quantum properties into the domains of space, time, and temperature that actually matter to life.

Photosynthesis and the Coherence Debate

Photosynthesis offers one of the most familiar examples. Living things employ particular pigments and proteins to capture light with nearly perfect quantum efficiency, turning almost every incoming photon into useful chemical energy. In 2007, fresh evidence indicated that life may achieve this through a quantum phenomenon known as coherence.

A chemist at Princeton University named Gregory Scholes was originally excited by that outcome. He and his team pursued experiments involving photosynthesizing proteins and pigments and reached comparable conclusions. Now, however, Scholes doubts that quantum effects actually play a part in living systems. Instead, he contends that life may merely mimic quantum behavior rather than employ it.

“Maybe quantum biology, at the biggest scales, means using 3 1/2 billion years of evolution to work out how to get the functionality that you could get from quantum systems,” Scholes said.

The Fragile Quantum State Problem

A quantum state is fragile. It falls apart when it comes into contact with anything outside itself. The smallest disturbance from its surroundings, such as the motion of atoms caused by warmth, can set off decoherence, which turns it into ordinary, classical behavior. Inside a living cell, decoherence ought to happen almost at once — quantum effects should vanish too quickly to matter for how life works.

Even inside a cell, extremely tiny particles such as hydrogen atoms can sometimes “quantum tunnel,” through energetic barriers that would otherwise hold them back or stop them from passing over. There is evidence that tunneling within particular enzymes might account for their swift performance.

The new research demonstrates that classical networks can generate the same mathematical structures as quantum systems, which means the phenomenon is a pattern-level result rather than something specific to individual particles.

A Century of Quantum Biology

Quantum mechanics has always carried with it a temptation to explain life’s mysteries through its strange rules, and that impulse dates back to the very beginning of the field. When the quantum pioneer Niels Bohr gave a 1929 lecture, he offered a vague but inviting statement about how quantum mechanics “may perhaps be of decisive importance, particularly in the discussion of the position of living organisms in our picture of the world.”

The physicist Pascual Jordan devoted much of his career to Quantenbiologie, asserting that living systems possess a distinctive power to magnify the uncertain nature of the quantum realm into everyday dimensions, which he regarded as the foundation of human intellect and free choice. The geneticist and evolutionary biologist J.B.S. Haldane seconded this view in a 1934 piece, contending that the capacity to elevate quantum uncertainty to ordinary size was precisely what distinguished life from other forms of matter. Jordan’s association with the Nazi Party and its armed organizations in 1933 harmed the standing of quantum biology by seeking to tie it to political extremism.

For decades, physicists who study the foundations of quantum mechanics have tried to reproduce parts of the quantum world using classical means, according to Markus Müller, a physicist at the Institute for Quantum Optics and Quantum Information in Vienna. What Scholes has demonstrated, Müller said, is that quantumlike behavior can arise from ordinary complex systems — the kind that exist everywhere in nature.

“Classical systems can mimic some of the key features of quantum information,” said Sabre Kais, a quantum chemist developing quantum computing algorithms for complex systems at North Carolina State University. “This is an exciting new direction.”

What This Means for the Field

The fresh findings do not resolve the debate over whether quantum forces play a role in living systems. They merely present another account for occurrences that once appeared quantum in nature. Should life manage to produce the same numerical designs using ordinary connections, the quantum reading might become superfluous.

This study offers a wider lesson about scientific inquiry. It suggests that the solution to a puzzle is not always a more fundamental level of reality, but rather a simpler pattern that appears consistent across vast distances.

Quantum biology is still wide open for exploration. Yet the newest findings hint that living systems might not require quantum mechanics to show quantum-like behavior. Complexity alone could be sufficient.

Source material: “Biology Might Not Be Quantum, but Its Math Is Quantumlike,” Quanta Magazine.

cellular physics · classical systems · photosynthesis · quantum biology · quantum coherence