Page 163 of The Secret of Secrets

“Exactly—it’s not even a real thing. I invented it in my book as a way to talk about a technology that does not exist. It would be a futuristic, ultrathin, flexible filament made of biocompatible material that can carry both electronic and ionic signals. Essentially, an artificial neuron.”

“And artificial neurons are not possible to create?”

“No, we’re not even close. Last year, two guys in Sweden made international headlines by persuading a Venus flytrap to open and close by chemically stimulating a neuron. Just a single binary impulse—and yet it sent scientific shock waves around the world. That’s the state of the art, Robert, and it’s generations away from an artificial neuron.”

Langdon was already moving across the room toward the window of the biology lab he had seen several minutes earlier. “Theoretically speaking,” he said, “would you build artificial neurons…or grow them?”

She thought a moment. “A nanoelectric biofilament? Well, it would be a biological filament, so you’d have to grow them.”

Langdon stopped at the window and peered at the machine with hundreds of long glass vials and tubes. “In a liquid suspension, I imagine?”

“Yes. Fragile microstructures are always cultivated in suspension.”

“Then I think you should come over here,” he said, waving her to the window. “It looks like Threshold is growing something…and I’m guessing it’s not arugula.”

Chapter 103

Everett Finch burst through the compromised entrance of Crucifix Bastion and stormed down the hall into the glass-walled atrium. Where the hell is everyone?! Enraged to find no trace of Housemore or the embassy’s promised security detail, he pulled out his personal RFID key card and headed for the elevator.

As he crossed the room, the key card’s biometric sensors activated in his fingertips, but he stopped short, reminded that there was no possible way for Housemore—or anyone for that matter—to access the elevator down to Threshold.

She must be upstairs…or else she left the bastion for some reason?

He dialed Housemore’s line one last time.

As soon as Finch placed the call, a phone began chirping nearby. Odd. The sound seemed to be emanating from a couch against the far wall. Did Housemore lose her phone? At least it would explain why she hadn’t answered earlier.

Finch strode to the couch but saw no phone. The ringing had stopped, and he called again. Once more, a phone began to chirp. Is it beneath the couch?

Finch crouched down to look under the stylish furniture.

As he stared into the dark space, he knew instantly that Threshold was under attack.

Staring back at him were two dead eyes—the lifeless gaze of his field officer Susan Housemore.

In the frigid vault, The Golěm gazed at the powerful machine sitting before him. The device’s gleaming metal body was a bulbous ring of polished aluminum that occupied nearly the entire concrete chamber. Five meters across and one meter tall, the machine resembled a giant metal donut. The unusual donut shape—technically “toroidal,” according to The Golěm’s research this morning—was apparently the most efficient shape in which to wrap superconducting coils if one wanted to create a magnetic field capable of storing vast amounts of energy.

SMES, he thought. Superconducting magnetic energy storage.

This was the secret source of Threshold’s power.

The Golěm had learned this morning that energy fed into the toroidal magnetic field would race in loops indefinitely with no degradation and could be siphoned off as needed. The only prerequisite was to keep the superconducting coils cold.

Extremely cold.

The critical temperature for its coils was somewhere below negative-260 Celsius, and if the coils rose even slightly above this temperature, they lost superconductivity and began resisting the current. That resistance caused rapid heating of the coils, which in turn caused more resistance, and within seconds the feedback loop blossomed out of control…resulting in a dangerous event known as a quench.

To prevent quenching, the coils were continuously flushed in a bath of the coldest liquid on earth. Liquid helium.

He gazed past the SMES to the adjoining chamber, where, locked within a Mu-metal mesh cage, stood twelve austenitic, stainless-steel tanks of liquid helium. Each of the five-hundred-gallon, Cryofab flasks stood as tall as The Golěm and was equipped with a cryogenic bayonet and vacuum-jacketed piping that transported the cold liquid into the SMES to keep the superconductors cold.

Liquid helium, by most measurements, was harmless—nonexplosive, nonflammable, and nonpoisonous. Its sole dangerous quality was possessing the lowest boiling point of any substance known to man…a frigid negative-270 Celsius. This meant that if the helium was permitted to “warm up” above negative-270 Celsius—already near absolute zero—it immediately boiled and converted to helium gas.

The gas itself was also harmless, but the danger lay in the physics of the conversion process. Liquid helium’s conversion to gas was shockingly fast and violent…and, as it turned out, it was the entire reason Threshold had co-opted the R2-D2 vent in Folimanka Park.

When liquid helium converted to gas, its volume multiplied by a mind-boggling ratio of 1 to 750. This meant that the liquid helium in this vault, if released, would rapidly convert to enough gas to fill seven Olympic swimming pools.

In an unvented space, the new volume would have nowhere to go, and the pressure buildup would happen so fast that it would create a “pressure bomb”—a near-instantaneous, violent outward force expanding in all directions. In a desperate attempt to make room for itself, the gas would blow apart whatever constrained it, resulting in a shock wave much like that of a tactical nuclear weapon, tearing through everything in a given radius.