“Any other possibilities on your list?” George asked.
“Just one,” said Alice. “The Snark might be a link to an intelligence located elsewhere. It might be the equivalent of a tiny radio receiver.”
“That requires structure, too,” said George, “but not as much. An optical fiber is considerably less complicated than a compact disc player. Or the musicians who made the music recorded on the CD.”
“But,” said Roger, “isn’t your Snark a bit, uh, short for an optical fiber link?”
George spread his hands. “Who can say? At any rate, I agree that a communications link hypothesis is more probable than your other alternatives, Alice. But is it for one-way communication or for two-way communication?”
Roger scowled. “Surely,” he said, “two-way communication is not a serious possibility. If the Snark was a link to an extraterrestrial intelligence, which I, for one, am not yet willing to concede, such an intelligence would have to be very far away. Hundreds of light-years, perhaps thousands or millions. Even if you did send a message that they were able to receive, you, and perhaps our whole civilization, would have died before the reply message came back. Remember your relativity, people. You can’t beat the speed of light!”
George looked directly at the theorist and grinned. “Roger, that’s all very logical, but I have a hunch you’re wrong. We have, as they say, a significant difference of opinion. So I’m willing to wager, say, five hundred dollars that two-way communication is possible using the Snark. You may accept my wager at whatever odds you consider to be fair and equitable. Interested?”
Roger looked flustered. “Uh, five hundred dollars? Let me, uh, think about that for a while, George,” he said. “Your intuitions have a certain reputation around here.”
“Two-way communication?” said Alice softly. “I hadn’t thought of that. How would you do it?”
“Well,” said George, “our Snark, by dumb luck, is already mounted in an almost ideal system. That lead-glass crystal is optically coupled to a photomultiplier light detector for receiving signals, and it has an onboard light-emitting diode system that makes light flashes in the scintillator for testing. We can use the LED system to transmit light pulses back to the Snark.”
“If you were going to send the Snark a message, Roger, what would you send?” Alice asked.
“Hmmm,” said Roger. “The conventional wisdom is that you should send back the same message you received. In this case, though, that might not be such a good idea. It could be interpreted as just a reflection. I’d say, send back a string of primes, perhaps at a different transmission rate, and don’t stop at prime number 144.
“But I think we must wait a bit before trying to communicate back. There are profound implications of that which need to be considered. I think there are even protocols established by the United Nations for communicating with alien species that should be observed.”
George turned to the theorist with a look of mock disappointment. “Do I take it then, Roger, old sport, that you don’t want to bet against me?”
37
GEORGE YAWNED AND LOOKED AT HIS WRISTWATCH. IT said JUNE 14, 2004, 06:55 A.M. After the excitement of the weekend, he was glad that he had remembered the appointment to use the microprobe.
The SSC’s superconducting metallurgy research laboratory was on the west campus, just across from the administration building. Wolfgang had arrived early and was already securing his prepared sample of two chips on the polished metal surface of the scanning microprobe stage when George arrived. They had received a brief lesson in how to use the device the previous Friday, and Wolfgang now had the system almost ready to go.
“Which chips are we testing first?” George asked. He considered the importance of this measurement. It could provide the key to their radiation damage problems, or it could be another blind alley. In either case, at 10 a.m. he would have to make a report on their progress. He hoped there would be something to report.
“One is from the new batch that just arrived from the chip foundry,” said Wolfgang, “and the other is one of our problem children. I thought we might learn something from a comparison.” George placed a loop of soft ductile indium wire on the lower vacuum flange and Wolfgang lowered the counter-weighted upper part of the apparatus down to meet it. Together they began to clamp down on the flanges, compressing the indium to form a metal-to-metal vacuum seal.
“Is the bad one the same chip we looked at with the STM?” George asked as he worked.
“Unfortunately, no,” said Wolfgang. “The STM probe did some surface damage to that one, and I thought it would be better to start fresh. However, this chip was mounted near the other in the pixel detector and shows exactly the same symptoms.” He moused START PUMPDOWN on the microprobe control computer’s screen. The roughing pump below the apparatus made a chugging sound as it removed air from the microprobe’s inner chamber.
As they waited for the vacuum to improve, George, still feeling the excitement of the weekend’s developments, began to tell Wolfgang about his recent Snark hunt. Wolfgang seemed interested at first and asked about the tracking and kinematics of the peculiar object. But when George began to describe the repetitive flashes and prime number sequences, Wolfgang’s attitude changed. He looked uncomfortable, as if George were describing something private and personal that he did not wish to hear about. Too bad, George thought, considering Wolfgang’s reaction. He had been hoping to recruit him to help with their Snark investigations.
Wolfgang got up, tapped the mechanical vacuum gauge unnecessarily, moused around the computer screen, and announced that the vacuum was now down below the top operating limit and the microprobe was ready. George nodded and Wolfgang started the imaging sequence. The scanning microprobe produced a beam of electrons that were scanned in a tiny raster pattern across the sample. The viewing screen of the device was scanned with the same raster and modulated in brightness by a current of scattered electrons received on one side of the device. The result was a startlingly realistic and sharply focused microscopic image of the scanned area.
The sharp image quality of the microprobe, however, was not the reason George and Wolfgang were using it. The scanned electron beam which the device used was unusually energetic, and when it struck individual atoms, it sometimes knocked out their inner-shell electrons, causing them to produce X rays with an energy characteristic of the producing atom. These X rays were detected by the device, and their energies used to color the microprobe image that appeared on the screen.
“Let’s find one of the destroyed FET gates on the bad chip,” said George.
Wolfgang moused a slide bar on the control screen, and the picture blurred, then stabilized. There was less magnification than the STM had provided, but the gate region was visible. Wolfgang found a gate where the characteristic hourglass shape had been distorted into two separated pink clumps. Around the ruined gate were clusters of green speckles.
“Green,” said George. “What does that mean?”
Wolfgang used the mouse to make a box around one of the larger speckles, then clicked on a control. A new window appeared. It showed the black points of the measured X-ray spectrum, a smooth variation ending in a series of spikes, overlaid in green with the matching reference spectrum that the computer had fitted to it. The graph label in the lower right of the window showed the green line of the fit with the symbol Cd.
“ ‘Cd,’ that’s cadmium,” said George. “What the hell would cadmium be doing on that chip?”
Wolfgang scanned other regions of the chip and found similar green speckles. He set a cut so the microprobe responded only to the cadmium X rays and backed off the magnification. A pattern became clear. Near the end of the chip where the tiny gold connection wires were attached there were concentrations of the material. He panned over to the new chip. No such areas were present. “It must have come from the manufacturing process used in that particular batch,” Wolfgang said.