The idea that human consciousness might arise from odd quantum phenomena has intrigued scientists, philosophers, and science fiction writers, inspiring debate about whether the “hard problem” of consciousness could be explained by quantum effects.

A sweeping new review published in Frontiers in Psychology takes a hard look at the field and concludes that though quantum theories of consciousness are becoming more experimentally grounded, none have cleared the enormous scientific obstacles required to explain subjective experience.

The paper, authored by Xun Ma and Aoping Wang of Xiamen University in China, evaluates some of the most prominent quantum consciousness theories using three key lenses: whether the proposed quantum effects can physically exist in the brain, whether they actually explain conscious experience philosophically, and whether they can be experimentally tested against conventional neuroscience models.

The researchers argue that many discussions related to “quantum consciousness” rely more on emotional rhetoric than on measurable science.

“Quantum-theoretical terms are often invoked in a largely narrative or analogical manner without specifying their precise physical meaning or empirical applicability,” researchers write. “This practice often lacks rigorous argumentation, remains insufficiently constrained by clear mechanisms or empirical support, and therefore does not yet provide a substantive solution to the problem of consciousness.”

In the past few years, interest in the idea of quantum biology has steadily increased. Scientists have already demonstrated that quantum effects can play functional roles in biological systems such as photosynthesis and bird navigation. But the leap from quantum chemistry to human awareness remains enormous.

Central to the debate is consciousness itself, which remains one of science’s most enduring and elusive mysteries.

Neuroscience has become increasingly successful at explaining how the brain processes information, stores memories, and controls behavior — what philosopher David Chalmers famously labeled the “easy problems” of consciousness.

The harder question is why physical processes in the brain produce subjective experience at all. Why does seeing red feel like something? Why is there an inner experience accompanying thought?

Quantum theories try to bridge that explanatory gap by proposing that classical neuroscience alone may be insufficient.

In their review, Ma and Wang focus on three major “families” of theories currently attracting scientific attention.

The first and most famous is the Orch OR theory, developed by physicist Roger Penrose and anesthesiologist Stuart Hameroff. This model proposes that quantum computations occur within microscopic structures within neurons called microtubules. According to the theory, coordinated quantum collapses inside these structures generate moments of conscious awareness.

The idea has long been controversial because the brain is warm, wet, and noisy, conditions generally considered hostile to fragile quantum states. Physicist Max Tegmark famously argued in 2000 that quantum coherence inside neurons would collapse far too quickly to matter for cognition.

However, researchers note that more recent laboratory experiments have produced intriguing results. Some studies have identified unusual quantum-optical behaviors in microtubules, including coherent oscillations and energy-transfer effects that persist longer than previously expected. Other experiments suggest anesthetic drugs may interfere with these microtubule dynamics, possibly supporting Orch OR’s claim that consciousness depends on quantum processes.

Still, researchers emphasize that nearly all of this evidence comes from simplified laboratory systems rather than living human brains.

“Current expositions of Orch OR tend to remain at the level of an intuition: if there are quantum processes, novel conscious states may arise, without stating a clear rule of derivation from quantum-state dynamics to the what-it-is-likeness of experience,” researchers write.

In other words, even if quantum effects exist inside neurons, scientists still have no explanation for why those effects should generate subjective awareness.

The second major theory examined in the review concerns nuclear spins and hypothetical structures known as Posner molecules. Proposed by physicist Matthew Fisher, the theory suggests that phosphorus atoms inside the brain may preserve quantum phase coherence long enough to influence neural processing.

Unlike electron-based quantum systems, nuclear spins are relatively immune to environmental noise, making them potentially more stable in biological tissue. The theory predicts that subtle differences between isotopes, atoms with different nuclear characteristics, could shape brain function or even consciousness itself.

Some experiments involving lithium and xenon isotopes have hinted at unusual spin-related biological effects. However, researchers stress that evidence remains sparse and heavily disputed.

Scientists have yet to directly observe long-lived quantum entanglement in Posner molecules inside living brains. Therefore, competing explanations rooted in conventional chemistry also remain plausible.

Ma and Wang describe the nuclear-spin hypothesis as scientifically intriguing but philosophically incomplete. Even if quantum spins influence neural activity, that alone would not explain why consciousness exists.

The third family of theories involves reports of large-scale “non-classical” signals detected using MRI scans. In 2022, research led by physicist Dirk Kerskens reported heartbeat-linked quantum-like signals in the brains of conscious participants. The findings generated immediate attention because they indicated the presence of macroscopic quantum effects across the entire brain.

However, critics quickly challenged the work, arguing that the observed signals could simply reflect conventional physiological artifacts associated with heartbeat and blood flow.

The new review notes that the controversy remains unresolved. Independent replications have not yet confirmed the findings, and the debate has become a case study in the difficulty of separating genuine quantum signals from ordinary biological noise.

Nevertheless, Ma and Wang maintain that these theories of quantum consciousness deserve serious scientific testing rather than outright dismissal.

Importantly, researchers praise the growing shift toward experimentally verifiable predictions. Unlike earlier eras of quantum consciousness speculation, modern researchers are increasingly proposing measurable hypotheses involving anesthesia, isotope substitutions, fluorescence signals, and cutting-edge imaging techniques.

That transition from abstract philosophy to laboratory science may represent the field’s biggest advance.

Researchers call for stricter scientific standards moving forward, including pre-registered studies, open data sharing, multi-center collaborations, and publication of null results. Because quantum consciousness claims are so extraordinary, they argue, the burden of proof must remain exceptionally high.

In their paper, Ma and Wang also repeatedly return to one key distinction: discovering quantum influences in the brain would not automatically solve the problem of consciousness itself.

Even if future experiments verify that neurons create quantum consciousness in some capacity, the central mystery of subjective experience could remain untouched.

“Quantum mechanisms, therefore, look, at the current stage, more like potential realizers of consciousness than like complete theories of consciousness,” researchers conclude.

That finding may frustrate anyone hoping for a definitive answer to the question of quantum consciousness. Yet, researchers propose that while no definitive answer exists, the field is slowly maturing from speculative theory into a more stringent scientific enterprise.

For now, the authors argue that caution and curiosity must coexist.

“In the explorations ahead, progress should be guided by the scientific method, advancing with a balance of curiosity and skepticism,” researchers write. “The riddle of consciousness remains profoundly complex: Quantum mechanics may be one piece of the puzzle, but a solution will likely require sustained multidisciplinary collaboration.”

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

In a new physics milestone, scientists report that a time crystal and an external system have been successfully linked for the first time.

The achievement, made by researchers at Aalto University’s Department of Applied Physics, marks the first demonstration of converting a time crystal—an unusual quantum system in which particles are in constant, repetitive motion in its ground state—into an optomechanical system.

A range of potential technological applications, including new high-precision sensors, quantum storage systems, and other innovative capabilities, could result from the research, led by Jere Mäkinen and detailed in a new paper appearing in Nature Communications.

A New First for Time Crystals

Conceptually similar to physical crystalline forms that occur in nature, time crystals were first proposed by Nobel Prize-winning physicist Frank Wilczek in 2012, who argued that comparable systems might also exist in time as well as in space.

Wilczek’s theory preceded the official experimental discovery of time crystals by just four years, which can be thought of as an unusual manifestation of matter whose motion repeats indefinitely.

In a recent study, Mäkinen, an Aalto University Academy Research Fellow, and his colleagues demonstrated that the properties of a time crystal could be altered, a feat never achieved before.

“Perpetual motion is possible in the quantum realm so long as it is not disturbed by external energy input, such as by observing it,” Mäkinen recently said. “That is why a time crystal had never before been connected to any external system.”

That is, until now.

“We did just that,” Mäkinen added, “and showed, also for the first time, that you can adjust the crystal’s properties using this method.”

Approaching Absolute Zero

Mäkinen and his team developed a system that used radio waves to propel magons—a variety of quasiparticles—into a superfluid made from a light, very stable isotope of helium known as Helium-3, which was chilled to temperatures approaching absolute zero.

Remarkably, the team found that after the radio-wave magnon “injector” was disabled, the magnons self-organized into a time crystal, which remained in motion for several minutes—an unusually long time for such systems—then eventually faded to a level the team said was no longer measurable.

During its weakening phase, the team also observed the time crystal interacting with a mechanical oscillator, in which changes in the device’s amplitude and frequency appeared to influence the time crystal’s interactions with it.

Into the Odd World of Opto-Mechanics

For Mäkinen and the team, the behavior they observed in the time crystal under such conditions was significant, in part because it aligned with phenomena in the field of optomechanics.

“We showed that changes in the time crystal’s frequency are completely analogous to optomechanical phenomena widely known in physics,” Mäkinen said. Such phenomena, Mäkinen says, are the same that scientists rely on for the detection of gravitational waves, for instance.

“By reducing the energy loss and increasing the frequency of that mechanical oscillator, our setup could be optimized to reach down near the border of the quantum realm,” Mäkinen added.

Fundamentally, Mäkinen says that the time crystal’s behavior with relation to optomechanical phenomena offers a promising pathway toward the control of time crystal behavior, which had previously been thought impossible. Such practical control systems for these odd states of matter could lead to applications that include quantum technologies and a range of other uses.

“Time crystals last for orders of magnitude longer than the quantum systems currently used in quantum computing,” Mäkinen said, adding that he and his colleagues hope their research may lead to ways they can be used to improve quantum computers by powering their memory systems.

“They could also be used as frequency combs, which are employed in extremely high-sensitivity measurement devices as frequency references,” Mäkinen added.

The team’s research was detailed in a new paper, “Continuous time crystal coupled to a mechanical mode as a cavity-optomechanics-like platform,” which appeared in Nature Communications.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.