As much as Langdon tried to open his mind to retrocausality, he found it impossible to accept. “But time moving backward makes no sense! There must be some other explanation.”

  “There is, but you won’t like it much better,” Katherine said. “The other possibility is that all the nutjob ‘universal consciousness’ folks are correct…and the universe knows all things. In this view, the universe isn’t bound by linear time as humans perceive it. Instead, it operates as a timeless whole where past, present, and future coexist.”

  Langdon’s head was starting to hurt. “What about your book? You were talking about the replication crisis…and how it plagues PSI and noetics?”

  “Yes, it does, like no other field, and it’s unfair.” Katherine took a sip of her drink. “Consider the field of athletics. If an athlete has an amazing Olympic result and sets a world record—something that has never occurred before, and which nobody else can replicate—we don’t decide the television cameras played a trick, or the audience was hallucinating. We see it simply as a remarkable result. Just because you can’t perform the same thing twice, that doesn’t mean it didn’t happen.”

  “Fair point…but that’s sports. This is science. Repeatability is a key part of the scientific process.”

  “Yes, and I agree that repeatability is a reasonable burden of proof at the macroscopic level. But at the quantum level, things work differently, Robert. The quantum world is understood to be unpredictable. In fact, unpredictability is quite literally its most agreed-upon trait!”

  Another fair point, he realized.

  “The language of the quantum world,” she said, talking faster now, “is literally the language of unpredictability—probability waves, quantum fluctuations, uncertainty principles, probabilistic tunneling, chaos, quantum interference, decoherence, superpositions, dualities. All of this translates loosely to ‘We don’t know what’s going to happen because the classical rules of physics don’t apply!’ ”

  “Okay, so consciousness—”

  “Consciousness is not a flesh-and-blood organ in your body. Consciousness exists in the quantum realm. It is therefore extremely difficult to observe with any predictability or repeatability. You can use your consciousness to observe a bouncing ball, but when you use your consciousness to observe your consciousness…you get an endless feedback loop. It’s like trying to observe what color your own eyes are, without the use of a mirror. As intelligent or persistent as you are, you can’t possibly know, because you can’t observe your eyes with your eyes—any more than you can observe your consciousness with your consciousness.”

  “Interesting. And you make this point in your book?”

  “Yes, along with the argument that repeatability, as a burden of proof, is an unreasonably high bar when studying consciousness. It’s doing damage to the field and destroying careers.”

  Langdon wasn’t sure how to respond. It was a fascinating concept, but in light of what they’d been through today, he had expected something more controversial…or dangerous…to warrant the kind of attention she had drawn. “So, this is the backbone of…your discovery?”

  “Heavens no!” Katherine laughed loudly. “I was simply explaining why consciousness is such an elusive beast to hunt. My discovery is tangible. I found something amazing through a series of experiments.” She leaned toward him and smiled. “And by the way, yes, these experiments I was able to repeat.”

  In Random House Tower, the elevator pinged, and Jonas Faukman stepped out onto a collage of colored floor tiles. The seventh floor was like stepping into a parallel dimension, a place where he knew his tension would dissipate. Here were none of the orderly bookshelves, muted tones, and straight lines that defined the other floors at PRH. The seventh floor was a winding maze of brightly colored “work pods” decorated with cartoon art, inflatable palm trees, beanbag chairs, and stuffed animals.

  Children’s books: playful decor. Serious business.

  In addition to this division’s pleasantly whimsical setting, Faukman appreciated that there was nothing childish about its coffee machine—a Franke A1000 with FoamMaster technology—a far cry from the Nespresso pods on the other floors. Sometimes, late at night, Faukman would sneak in here with a manuscript, make a double espresso, and plop down in a beanbag chair to edit under the watchful eye of a giant Winnie-the-Pooh on one side of the lounge and the mischievous smile of seven-foot-tall Cat in the Hat on the other.

  Tonight, as the machine ground his coffee, Faukman breathed in the aroma, trying to ease his fears. The arrest of the operatives downstairs should have been a relief, but he felt no real contentment; the whereabouts of Robert and Katherine were still unknown, and he felt increasingly desperate to know they were safe.

  Alex Conan had already solved one vexing question:

  Who stole Katherine’s manuscript?

  But the startling answer now begged a second question.

  Why?

  Jonas Faukman had devised a plan to unravel that mystery.

  CHAPTER 73

  We need to hurry, Langdon thought as the limousine climbed the steep switchback curves traversing Chotek Gardens. The “Prague 6” neighborhood that housed the ambassadorial residence was a matter of minutes from here, and Langdon desperately wanted to know everything he could about Katherine’s book and her discovery. Before we face the ambassador, he thought, still uncertain whom to trust.

  Katherine continued. “In the nonlocal consciousness model, your brain is a kind of radio that receives consciousness, and like all radios it has countless stations bombarding it all the time. So you can immediately understand why a radio must have a tuning dial—a mechanism that enables it to choose which single frequency it would like to receive. The radio itself has the capacity to receive all stations, but without a way to filter the frequencies that flow in, it would play all those frequencies at once. The human brain works the same way; it has a complex series of filters to prevent the mind from being overloaded with too much sensory stimulus…so it can focus on only a small sliver of the universal consciousness.”

  That makes perfect sense, he thought. Our perception of light and sound is filtered. Langdon knew that most humans were unaware that they experienced only a small fraction of the practical frequency range and electromagnetic spectrum; the rest sailed by us, beyond our tuning dials.

  “Selective attention is a prime example of filtering by the brain,” Katherine said. “It’s called the ‘cocktail party effect.’ Picture yourself at a crowded party with your brain focused solely on the words coming from the person who is speaking to you—and then you get bored, and your focus switches effortlessly to a more interesting conversation halfway across the room. It’s what enables you to filter out background noise and not be overwhelmed by every voice within earshot.”

  Faculty meetings, Langdon thought, often catching himself tuning in to music outside on the quad while his colleagues debated the curriculum or scheduling.

  “Habituation is another kind of filtering,” Katherine said. “Repeated sensory input is blocked by your brain so effectively that you literally cannot hear the incessant hum of the air conditioner or feel the pair of glasses sitting on your nose. That filter is so powerful that we can search the house for glasses that are literally right before our eyes, or a phone clutched in our hand.”

  Langdon nodded. He had not felt the Mickey Mouse watch on his wrist for decades.

  The concept of “filtered reality,” he knew, was a recurring theme in ancient scripture. The Hindu Vedanta, which had inspired the great quantum physicists like Niels Bohr and Erwin Schrödinger, described the physical mind as a “limiting factor” that could perceive only a fraction of the universal consciousness known as Brahman. The Sufis defined “mind” as a veil that disguised the light of divine consciousness. The Kabbalists described the mind’s klipot as obscuring most of God’s light. And the Buddhists warned that the ego was a limiting lens that made us feel separate from the universe—uni-versum—literally “everything as one.”

  “And modern neuroscience,” Katherine continued, “has now identified the actual biological mechanism by which the brain filters out incoming data.” A faint smile crossed her lips. “It’s called GABA. Gamma-aminobutyric acid.”

  “Okay.” Langdon was reminded that most of Katherine’s postgraduate work had been on the brain’s neurochemistry.

  “GABA is a remarkable compound—a chemical messenger in your brain that plays a critical role in regulating brain activity. But probably not in the way you’d think. Specifically, GABA is an inhibitory agent.”

  “Meaning, it impedes brain activity?”

  “Exactly. It actually decreases neuronal firing and constrains the overall activity of neurons. In other words, GABA shuts off parts of the brain in an effort to filter out excessive input. In our most basic understanding of it, GABA filtering ensures the brain does not become overloaded with too much information. In the radio analogy, GABA is like the tuner that limits reception to a single frequency while blocking out dozens of others.”

  “Makes perfect sense so far…”

  “GABA really caught my eye a few years ago,” Katherine continued enthusiastically. “I read that the brain of a newborn baby has incredibly high levels of GABA, filtering out everything except what is directly in front of its face. Newborns are therefore virtually unaware of details across the room. The filters work like a set of training wheels, protecting the baby’s mind from too much stimulation as it develops. As we mature, our GABA levels slowly decrease, and we take in more of the world and gain wider understanding.”

  Fascinating, Langdon thought. He had always imagined a newborn’s tiny field of perception was because it couldn’t see very well.

  “So I started researching further,” Katherine said, “and learned that Tibetan monks also exhibit exceptionally high levels of GABA during meditation. The meditative trance apparently causes a surge of the inhibitory neurotransmitter, which shuts down nearly all neuronal firing, essentially preventing most of the outside world from entering their brains during deep-state meditation.”

  The elusive empty mind, Langdon thought, familiar with the goal of meditation but never having known the chemical process by which it was achieved. Literally blocking out the world…reverting to the purity of the newborn mind.

  “I suppose the results were not that shocking,” Katherine said, “but they gave me an idea—the concept of human consciousness being a signal…flowing into the brain through a series of gates.”

  “Gates that decide how much of the world to let in.”

  “Exactly, and it was about eighteen months ago, during my further research into GABA, that I stumbled across a neuroscience paper…written by Brigita Gessner.”

  Ah yes, Langdon thought, which sparked Katherine’s invitation to speak in Prague.

  “Gessner’s paper,” Katherine revealed, “was about an epilepsy chip she had invented that could thwart an oncoming seizure by triggering the brain’s natural GABA response, literally ‘calming’ the nerves. It made sense. As it turns out, epilepsy is a condition often related to dangerously low levels of GABA, which is the brain’s braking mechanism. With too little of it, your brain goes into overdrive, has runaway neuronal firing, and ultimately—”

  “A seizure.”

  “Yes,” she said, taking a quick sip of her Kofola. “The chaotic electrical storm of an epileptic seizure is the exact opposite of the focused blank mind of a monk in meditation; seizures are associated with a deficit of GABA…and meditation with an excess. I was familiar with all this previously, but her paper reminded me that epileptic seizures are often followed by a pleasurable refractory period known as postictal bliss—a peaceful, expanded state of consciousness, accompanied by bursts of connectedness, creativity, spiritual enlightenment, and out-of-body experiences.”

  Langdon recalled his experience earlier with Sasha, as well as the descriptions offered by history’s innumerable visionary epileptics.

  “And I suddenly found myself wondering,” Katherine said, “how an epileptic brain could so quickly transition from the storm of a seizure…to the peace of postictal bliss.”

  Langdon shrugged. “I’m guessing a natural spike in GABA levels…quiets the storm?”

  “Great guess—it was mine too—it’s called rebound inhibition, and it does indeed occur, but not immediately. As it turns out, something else happens first. The brain reboots. The whole system shuts down. And when it comes back online, it does so gradually…buying time for the brain to restore its GABA levels, reengage its filters, and shield the waking brain from too much input.”

  “Sounds like how we wake up in the morning…opening our eyes slowly to give our pupils time to constrict and filter out some of the morning light.”

  “Exactly! Except in this scenario, we never see the true morning light, because as we wake up, someone is simultaneously pulling thick curtains across our windows so we can’t see what’s really outside.”

  “And that someone, I’m guessing, is GABA?”

  “Precisely. GABA usually closes the curtains in time, before our eyes are open. But if the timing is off, and the curtains don’t close quickly enough—”

  “We catch a glimpse of the outside world.”

  “Yes,” she said with a smile. “And apparently it’s beautiful. Unfiltered reality. Postictal bliss. Pure consciousness.”

  Remarkable, he mused, wondering if some of history’s celebrated “flashes of genius” might be attributable to a timing glitch…a brief moment when the doorway to reality was mistakenly left ajar.

  “The more I thought about GABA,” Katherine said, “the more I realized that GABA was the key I’d been looking for…”

  “The key to…?”

  “The key to understanding consciousness!” she exclaimed. “Human beings have extraordinarily powerful minds, but we also have extraordinarily efficient filters to prevent an overload of input. GABA is the protective veil that prevents our brains from experiencing what we can’t handle. It limits how expansive your consciousness can be. This single chemical may be the reason why humans are not able to perceive reality as it truly is.”

  Langdon sat back on the plush limousine seat, absorbing the provocative idea. “You’re suggesting there’s a reality around us…that we can’t perceive?”

  “That’s exactly what I’m suggesting, Robert.” Her eyes flashed with excitement. “But that’s not even the half of it.”

  In the Old Jewish Cemetery, the sounds of the nearby bustling streets had faded from The Golěm’s perception…his mind now bathed in a welcome silence. On his knees, he absorbed the power of this hallowed ground…listening for the voice of his predecessor.

  With no true birthplace of his own, The Golěm called this place home, visiting from time to time when he needed strength.

  The first golem went mad…but I am stronger than that.

  His visits to this site always centered and replenished him, but today, he felt especially fortified. As he opened his eyes and stood to face the task before him, a light breeze whispered through the cemetery. The Golěm heard the voice of the original golem…a single word rustling in the bare branches overhead.

  Truth…

  He pictured the ancient letters on his forehead. The truth of his purpose in this realm was to protect a beautiful soul who lacked the strength to protect herself. The truth was that she would not be safe until The Golěm carried out his acts of retribution.

  “There are only two paths,” the wind whispered in the trees. “Truth or Death.”

  The Golěm had already made his choice.

  I choose both.

  CHAPTER 74

  The limousine was approaching the posh neighborhood of Bubeneč, and Langdon knew the ambassadorial residence was not far off. Transfixed by Katherine’s revelations, he was eager to hear the rest.

  There’s a reality around us that we can’t perceive?

  “The idea first dawned on me,” Katherine continued, “while I was researching the postictal experiences described by epileptics,” she explained. “I suddenly realized that their blissful experiences were remarkably similar to the accounts of another group.” She paused, her eyes alight. “Those who have died…and come back.”

  Near-death experiences, Langdon thought, realizing she was right. Following the trauma of near death or a seizure, both groups reported an untethering from the body, a deep connection to all things, and a profound sense of peace.

  “So I ran with that idea…and I devised an unusual experiment.” Katherine gave him a quiet smile. “And this is where things really got interesting. First, I located a terminally ill patient not too far from my lab—a retired neurologist himself—who agreed to undergo his death process while enclosed inside a new kind of imaging machine—a real-time magnetic resonance spectroscopy device. I explained that I would be able to watch his brain chemistry moment by moment as he died. He felt gratified by the chance to provide accurate data like we’ve never been able to measure previously. With his family and hospice staff gathered around on a lovely afternoon, he passed away while being scanned inside the massive machine.

  “Throughout the dying process,” Katherine continued, “I saw rapidly rising levels of key neurotransmitters—including adrenaline and endorphins, which function to subdue pain and help the physical body through the stress of the death process. In other words, a shutdown of the sensory systems. It followed logically that GABA levels would also increase—to filter out the death experience as the brain shut down.” Katherine smiled. “But that’s not what happened.”

  “No?”

  “What happened was the exact opposite! As he died, his GABA levels dropped precipitously! In his final moments, GABA levels approached zero, meaning all of his brain filters were gone. The entire death experience was flowing in—with nothing blocked out!”