A possible answer, they said, to the eerie silence—the failure to detect any extraterrestrial transmissions—was that there are in fact no other life-forms currently extant. But another possible answer, they contended, was that we’ve misunderstood interstellar etiquette. Perhaps aliens don’t speak until spoken to. They could well be aware of our presence, thanks to our decades of leaking signals out into space, but it might be incumbent upon us to make a gesture that indicates we are beings of goodwill.
Just passively listening, they said, is plain lazy: It implies that we prefer for others to do the heavy lifting of composing messages and beaming them with great power at specific stars. Worse than that, it also shows that we’re greedy, expecting others to give things to us. Any civilization we could contact, they pointed out, will almost certainly be more advanced than our own; the universe is almost fourteen billion years old, and we’ve only been a radio-capable species since 1895. Civilizations around other stars might well be thousands, millions, or even billions of years ahead of us. We could gain enormously in terms of knowledge through contact with them; they, on the other hand, would have relatively little to learn from us. Since we would have more to gain, they argued, perhaps it’s expected that we should invest more, by being the first to reach out.
But others had considered this to be dangerous naïveté. First, they said, the underlying assumption that any advanced civilization must be peaceful and altruistic could be wrong. And even if some were, surely, they said, it was possible that others were not. One possible explanation for the Fermi paradox—the fact that although our science suggests that the universe should be teeming with life, all SETI efforts have so far failed—was that there is a violent berserker race that makes it its business to wipe out any civilizations it detects. Whatever other races might still exist locally may have learned by observing this that remaining silent was crucial to survival.
Nonetheless, the METI advocates pushed forward with amendments to the SETI protocol that would allow and encourage direct and immediate proactive transmissions designed specifically to signal our presence to other civilizations. This prompted a rash of resignations from the international commissions involved in drafting the protocol. These self-styled dissidents felt that no overture toward contact should be made without wide-ranging international and interdisciplinary consultation and consensus.
The debate continued to rage here in 2030, but those favoring active SETI had crowed victory when it became clear that the advanced beings at 47 Ursae Majoris had done precisely what they’d proposed humanity should be doing: Those aliens had boldly and deliberately announced their presence to the universe.
Many of the players on both sides had changed since the argument had begun—some had retired, others had died, a couple had even switched positions—but, at last, the opponents of active SETI had gotten what they’d wanted all along: Rather than a few individuals behind closed doors deciding a matter that could have a profound impact on the entire planet, broad public discussions were now occurring. The METI dissidents were finally getting their day in court.
“Ursula,” Professor Sudeyko said, “we humans have a history of considering ourselves special, so forgive the vanity, but is it safe for us to assume that ours was the only world you sent the Reticulum to?”
Ursula clasped her two right arms together. “I’m afraid not. We identified eleven other systems that might have intelligent life. They each got sent copies.”
“Was there anything special about us?”
“Well,” she said, “your star system was the furthest one we sent the Reticulum to. My home system of 47 Ursae Majoris and yours of Sol are forty-six of your light-years apart. But we also sent the Reticulum to 20 Leonis Minoris, which is just twelve of your light-years from us; SV Leonis Minoris AB, just fifteen light-years away; 61 Ursae Majoris, sixteen light-years away; Groombridge 1830, seventeen light-years away—”
Sudeyko held up a hand—and Ursula was as good now at interpreting human gestures as Emily and others were at understanding alien ones. “Thank you,” he said. “And have any of these other systems sent you a reply?”
“The short answer,” said Ursula, “is ‘not yet.’ But, of course, that is a slippery concept in these matters. We made all of the transmissions over a period of three of our years, with the one to you, seeing as it had the farthest to go, being sent first. I have no idea if a reply has been received since that transmission.”
“So,” said Sudeyko, again facing the jury, “you don’t actually know if there were negative consequences to, if I may phrase it this way, shouting in the jungle?”
Emily and her team had spent months combing through the ever-growing data set from the array of radio telescopes. She’d joked to one of the other data-mining specialists that it was like looking for a needle in an infinitely expanding haystack.
If there had been a blindingly obvious signal, such as the first five prime numbers repeated in a very powerful broadcast, the real-time scanners would have caught it as it came in. So, if there was something buried in here, it was likely both a weak signal and a subtle one. Still, there are ways you can tell if something has information content—Zipf plots were one such tool—and other ways, such as Shannon entropy scores, for determining how complex the content is, even if you couldn’t decipher a word of it.
Emily knew the chances of finding anything were slim, but, nonetheless, she kept designing new techniques, tweaking algorithms, modifying filters, and—
—and there it was.
My God.
She’d found it.
She’d found Gordo.
And just like Gordo—just like sauropods, by far the largest land animals ever to exist—it was huge. Gigantic. Not just terabytes. Not petabytes. No: more even than that. Exabytes—quintillions of bytes. She double- and triple-checked, ran some more tests, and then checked again, just to be sure. There had, after all, been numerous false alarms related to SETI signals. The first pulsar discovered in 1967 was dubbed LGM-1 for “Little Green Men One,” because it appeared to be an extraterrestrial beacon, and, in 2015, a signal candidate from the Parkes Radio Observatory in Australia turned out to just be noise from the microwave oven in the lunchroom.
But, when Emily was totally sure, she picked up her phone and said, “Call Hannah Plaxton.”
“It’s after 2 a.m.,” the phone replied. “Are you sure you want to call so late?”
Emily was surprised at the time. Stilclass="underline" “She’s an astronomer. She’s used to being up at night.”
“She’s a radio astronomer,” replied the phone. “She works during the daytime.”
Well, the phone had her there. “All right. But if Hannah comes online overnight, wake me. And book me a flight for tomorrow morning to go see her.”
In 1980, Carl Sagan had popularized the idea of an Encyclopedia Galactica, opining that aliens might someday be so kind as to beam such a thing to us. Back then, Sagan probably considered the Encyclopedia Britannica the pinnacle of human knowledge, and not just because he was a contributor to it. But for all his forward thinking, Cosmic Carl was a product of his time; no encyclopedia could properly systematize all that humanity had learned, although the few remaining Wikipedians still gamely tried.
In 2009, SETI pioneer Seth Shostak started advocating that if humanity were to transmit anything to the stars, it might as well transmit everything, broadcasting the whole World Wide Web. The modern Web would take months to send via microwave, but the whole darn thing could be beamed to a specific target via optical broadband in less than a day.