Here’s what you’ll learn when you read this story:

• Scientists are using terahertz waves to study tiny structures in brain cells, called microtubules, that may be linked to consciousness.
• Early experiments suggest microtubules behave differently under anesthesia—when consciousness is clearly altered—but evidence remains inconclusive.
• Now, researchers are debating whether quantum effects in the brain are real, measurable, or simply theoretical.

If you’ve been in an airplanebefore, it’s probably happened to you: walking through an airport body scanner, a dreaded Beep! Beep! Beep! resounds, signaling that it caught some forgotten coin, key, or even a crumpled receipt that you mistakenly left in your pocket. That moment comes courtesy of millimeter waves, otherwise harmless high-frequency radio signals that bounce off your body to reveal hidden objects.

Terahertz (THz) waves are close relatives of millimeter waves, but they sit even higher on the electromagnetic spectrum, meaning they can read the subtle vibrational “fingerprints” of molecules without the damaging effects of x-rays. That makes them especially useful for studying soft, shifting structures like microtubules as they move inside living cells. But rather than use them to find loose change, scientists are aiming terahertz waves at the brain itself. Their mission? To see if microtubules—the cell’s tiny scaffolding tubes—flutter with quantum vibrations that vanish under anesthesia and rebound when consciousness returns.

Data from animal studies suggests this is the case. In 2024, researchers at the University of Maryland gave rats compounds that stabilize microtubules. They noticed that the animals took longer to lose consciousness under anesthesia—an indication that these protein tubes could play a role in awareness. Rather than using terahertz scanners, the team altered the microtubules directly to see how the brain responded.

But studying microtubules inside a living brain is far trickier—you can’t just tweak them with drugs and watch what happens in real time. Enter terahertz scanners.

Think of them as a new frontier, not a fait accompli: so far, terahertz tools have helped with prepared samples, like thin slices of tissue, where they pick up how molecules move and vibrate. The goal is to eventually use them to track those same tiny shifts inside the intact brain—without having to interfere with it. If upcoming studies show that terahertz waves can reliably detect this faint molecular activity inside the working brain, these scanners could become the first noninvasive window into the quantum heartbeat of awareness.

But is it really that simple? Skeptics point out the obvious: Anesthesia changes everything about brain activity. Maybe these signals are just noise or heat artifacts.

“These experiments are exciting in concept because they try to connect a measurable physical signal with a profound state change such as anesthesia,” says Lea Gassab, PhD, postdoctoral scholar at the University of Waterloo’s biology department. “For them to be convincing, though, they need to be reproducible, to exclude trivial effects like heating or scattering, and to show that the signal is genuinely linked to neural function and not just a side effect. At the moment, they raise interesting possibilities, but more evidence is required before they can be seen as proof.”

“When we see a striking experimental result, it is tempting to treat it as a victory or defeat for a theory,” echoes Onur Pusuluk, PhD, assistant professor at Kadir Has University. “But the first question should be: are the experiment and the theory really looking at the same thing?” He points to past cases in photosynthesis and smell research where early quantum effects were either misread or prematurely dismissed because molecules had been pulled out of their natural biological setting. “These stories remind us that science advances only when theory and experiment speak the same language about the same system.”

In February 2025, Gassab, Pusuluk, and an international team published a perspective in the peer-reviewed journal Entropy titled “Quantum Models of Consciousness from a Quantum Information Science Perspective.” This put three bold “quantum mind” ideas under the microscope. The first was the microtubule theory of Roger Penrose and Stuart Hameroff, which sees those tiny protein tubes inside neurons as possible quantum computers of the mind. The second was the electromagnetic field theory, which suggests the brain’s own electromagnetic field could bind neural activity together into a single stream of thought. And the third was Matthew Fisher’s Posner cluster idea, where phosphate molecules can join up into tiny tetrahedral cages—pyramid-like shapes—that may shield fragile quantum states long enough to influence memory. Gassab’s team ran simple spin models to stress-test them in the brain’s hot, noisy environment. The verdict? Posner clusters stand out as the best bet, while electromagnetic fields might help explain how distant brain regions sync up. The microtubules? Well, they still look a bit… speculative.

It’s not that microtubules are useless: “They are interesting because they are highly ordered and dynamic polymers [long chains of repeating molecules] present throughout neurons. They are not only structural scaffolds but also interact with transport and signaling,” says Gassab. “Yet it takes more than a neat tube to make a mind. Their lattice-like geometry makes them attractive for studying collective physical phenomena, yet the evidence tying them to cognition or consciousness just isn’t there yet. Microtubules are good candidates to study quantum effects in biology, but any connection to brain behavior remains hypothetical and must be approached with caution,” she says. And you need to factor in that the brain is a warm, messy environment—more like a hydrothermal vent than a quantum computer.

Today, quantum computers need to be chilled near absolute zero to keep their fragile quantum states alive. The brain, meanwhile, hums along at 98.6°F—a noisy soup that seems like the last place for quantum tricks. MIT physicist Max Tegmark even crunched the numbers and found that any quantum effect in microtubules would unravel in about 10⁻¹³ seconds—basically instantly at body temperature.

“This makes coherence difficult to maintain [coherence is that fragile state where quantum waves march in lockstep instead of collapsing into noise],” says Gassab. “But we must remember that everything in the brain—proteins, electrons, ions, particles—is already quantum by nature,” she is quick to add. “The real question is whether biological structures can preserve these effects long enough to influence function. Nature is often surprising.” Even if they cannot, Pusuluk argues that quantum effects might still matter even if they disappear almost instantly. “People often assume that for quantum effects to matter in the brain, they must survive for a long time. But that isn’t necessarily true,” he says. In decoherence—the process by which fragile quantum states break down into ordinary, classical behavior—quantum links don’t simply vanish but can leave behind broader patterns of coordination. Pusuluk suggests that, in principle, those classical echoes could show up as synchronized rhythms between neurons, a hallmark often tied to conscious states.

For other physicists, though, microtubules might be part of the puzzle and terahertz scanners intriguing tools of the trade—but neither deserves the center stage.

“There are odd cases—like people with Alzheimer’s or dementia recalling memories from decades ago,” says Michael Pravica, PhD, a physicist at the University of Nevada, Las Vegas. “My grandfather in his 90s always recalled events from the 1920s. If microtubules are short-term storage, how do you explain that? I think it’s more about neural pathways creating holographic patterns. Memories form pathways—when illuminated, they recreate images, smells, or sounds. That’s holographic storage.”

Then, almost casually, he adds a metaphysical twist. “One question I can’t fully explain: When you go under anesthesia, brain activity drops. How does the brain restart? My theory is that the wave function may go into a gland—believed to be a gateway to other dimensions—and become quiescent until restarted. Microtubules may maintain some of that information and help restart the waves.”

Pravica doesn’t reject the idea of microtubules outright but frames them as supporting players. It’s just that he thinks we are missing the forest for the tree. “The brain is a medium, waves are the message, and consciousness is the wave pattern,” he says. Neurons and microtubules might matter as launch pads, but what counts are the waves they set in motion—and how they interfere.

That tension—between speculative leaps and grounded lab work—is palpable in the field of quantum physics. Even Gassab, who stresses reproducibility, keeps the door open. “Quantum approaches suggest that consciousness may not be fully explained if we see neurons only as classical circuits,” she says. “Some thinkers propose that consciousness could be something fundamental, like a quantum field. Personally, I think at this stage in time we should be open to all views.” This is why she and her peers study microtubules, Posner clusters, and other exotic ideas. “In reality there may be many candidates, and perhaps several are true or none are,” Gassab says.

Whether consciousness is just biology, a quantum trick in microtubules, a wave hologram, or something we haven’t yet discovered, admitted, or dared to imagine, one fact remains: The brain is still the most mysterious medium in the universe. “Even the word consciousness is not well defined,” Gassab says. “We do not yet understand this brain that can ask questions about itself. Our ability to reflect on our own thoughts is itself remarkable.” For now, the scanners can listen, and the theories can hum.