One week later, she discovers something interesting:
"It emits alpha particles." Lang clears the center of the lab's largest table and unfurls a long, thin strip of paper across it. She flattens it with both her palms, then pins it down via several strategically positioned flasks and a sample of radioactive ore. The sheet contains a series of jagged lines in groups of tightly clustered spikes.
Hutchinson leans over the table and examines the markings. He scowls. "I thought radiation couldn't penetrate it."
"Yes and no. Regardless, it emits radiation. Several bursts over a minute. Professor Scranton's laboratory has a Geiger counter which I borrowed and modified for our purposes. Each 'peak' represents a burst. And that's not all. Look close."
Cabenwald examines the sheet along with Hutchinson, fishing in his pocket for his reading glasses. Meanwhile, Hutchinson sees what Lang has found. He makes a sharp, excited sound.
"What?" Cabenwald finally gets his spectacles on. He sweeps his eyes up and down the roll of paper. "What is it? I see nothing of note. It appears to be random."
"Here." Lang points out a small section. "See this? A series of evenly-distributed pulses, each containing an increasing number of peaks. It continues to grow for five more iterations before 'vanishing' into the noise. You see the same series again, here. And one more time, here."
"Very brief. Are you certain this is not a coincidence?"
"Oh, yes, she's certain." Hutchinson restlessly shifts from foot to foot. He can barely contain himself.
"How can you be so sure? I admit, a repetition of three is unusual, but — "
Hutchinson elbows him. "Count them, Gregory. Count the peaks in each grouping."
Cabenwald does so: "First one has two, next one has three. After that, five. Then, hm, seven, and — that one is — eleven — and, oh. Oh. Oh, my." His eyes widen.
Lang grins. "Primes. The first six."
"My God."
"There is one more matter," she tells them. "I previously concluded radiation could not penetrate it. That was on account of radiation not passing through it — but it only occurred to me today to test whether radiation was being deflected. It is not."
Now it's Hutchinson's turn to look puzzled — and Cabenwald's to brighten with excitement:
"It absorbs it. Perhaps even transmits it."
"Precisely. I suspect the pattern is a message — a message from where this object came. And I suspect we can use the same method to send something back."
Two weeks later, they have established a technique to transmit signals.
The hardest part proves to be the reliable production of alpha particles. For this, polonium is required; its scarcity (a consequence of its brief half-life) makes it prohibitively expensive. Hutchinson calls in favors from several wealthy friends to secure the necessary components.
The second challenge is the device itself — a contraption that can emit a timed burst of alpha particles in a single direction. For this, Lang and Cabenwald work together. They devise a lead-shielded mechanism that, when triggered, releases a ray of alpha particles from the tip of a small barrel.
The mechanism is automated. It is powered by two hand-made chemical batteries, and controlled via a punch-tape feed. The pattern on the punch-tape determines at what points the ray will fire. This design allows them to loop a pattern for as long as their supply of polonium lasts.
Given the content of the arriving message, they decide to respond by escalating the stakes: they transmit the first seven primes.
Immediately after their first loop completes, the modified Geiger counter stops moving.
Several seconds after that, it frantically starts to scribble.
"Good God," Cabenwald mutters. "How much is —"
"They're replying. Turn off the — " Before Lang can finish her sentence, Hutchinson has disconnected the Leclanché cells from their device. Now, all three are watching the strip of paper that emerges from the Geiger counter. It is covered in dense, tight clusters of peaks and mesas, with each cluster separated by an equally-spaced interval.
Hutchinson approaches and examines the strip. It spools through his fingers.
"Well?" Lang scoots toward him, searching the clusters for any clues as to their nature. "What is it?"
"I cannot tell. There's more than just peaks, now. These broad bands — periods where they kept emitting for a full second or longer. I don't know what these mean. Is it — "
The scribbling stops. Lang immediately checks the counter; everything is in working order. The message has completed.
"This is Morse code." Cabenwald steps over the strip of paper on the floor, then lifts and examines a segment of it. "When I was a young lad, I worked in the telegraph office at Penn Station. Learned to read Morse as easily as a plain English."
"They sent us a telegram?" Lang asks, puzzling over the idea. "What does it say?"
Cabenwald doesn't respond. Instead, he keeps reading. His expression is somber and contemplative.
"For Jehovah's sake, man! Don't keep us in suspense!" Hutchinson fumes. "What the blazes does it say?!"
"It says to stand by for a second transmission in precisely one hour. It shall exceed five million characters, and thus will take approximately two hundred and sixty days to complete."
The room is silent for quite some time.
"In that case," Hutchinson says, "I suspect that we will require an extra roll of paper."
