A Glass Dipped in Ocean

Where Is Everybody?

Eli: Before sunrise on April 8th, 1960, at Green Bank, West Virginia, Frank Drake turned an 85-foot radio antenna toward two nearby Sun-like stars, each about 12 light-years away. It was humanity's first scientific search for extraterrestrial intelligence. Drake called it Project Ozma.

Mara: And a listener has asked the question Drake was chasing that morning: are we alone in the universe, and if not, why haven't we heard from anyone?

Eli: Drake's bet was that the question could be tested with a radio dish instead of just argued over. What he heard, and what everyone's heard since, still hasn't settled it. Today's angle is decades of cosmic silence and the limits of the search.

Mara: And he was doing it when, in his own words, “Searching for intelligent life was considered bad science in those days.”

Eli: And Ozma heard only static. Drake later summed it up: “That was a disappointment.” But a year and a half on, he invited people back to the same observatory.

Mara: November 1961, Green Bank, the first meeting ever devoted to this. Before the guests arrive, Drake writes an equation on the blackboard. It's the agenda, written as maths. Start with how fast our galaxy makes stars, then how many have planets. Multiply by the fraction of planets where life arises, then where life turns intelligent, then where it builds radio we could detect. Last comes how long such a civilization keeps transmitting. Seven factors, and out comes the number of civilizations in the galaxy we could actually hear.

Eli: The guest list: a planetary astronomer, a biologist, a physicist, a radio engineer who invited himself.

Mara: And one guest learned mid-meeting he'd won a Nobel Prize. Respectable company for bad science.

Eli: That blackboard had an older shadow. Around 1950 at Los Alamos, Enrico Fermi walked to lunch with a few colleagues. One of them recalled a New Yorker cartoon from that spring: little green men carrying New York trash cans toward a flying saucer. Fermi joked it was a very reasonable theory, because it explained two things at once, the saucer reports and the vanishing trash cans. Then, at lunch, he asked, “But where is everybody?”

Mara: Accounts differ on the year, who was at the table, and his exact words.

Eli: The gist survives, though. One colleague remembered Fermi running the odds: Earthlike planets, life on them, humans from life, how long high technology lasts. That clash, high odds that someone's out there and no evidence of anyone, became known as the Fermi paradox. In 1975, Michael Hart argued that a civilization able to cross between stars could fill the entire galaxy in a few million years.

Mara: Which leaves an awkward gap, Eli.

The Unbroken Silence

Eli: And the listening went on. Then in August 1977, Ohio State's Big Ear radio telescope logged something from the direction of Sagittarius. Days later an astronomer going over the printout found it, circled the reading “6EQUJ5” and wrote “Wow!” beside it. The name stuck.

Mara: Those six characters recorded how strong the signal was.

Eli: And it never came back; nobody has detected it since. Seth Shostak of the SETI Institute puts the consequence bluntly: “In science, if you come up with an experimental result that cannot be replicated, then it's really impossible to say that you know what caused it.”

Mara: The Wow! is just the famous case. No search since has confirmed an artificial signal.

Eli: So, decades of nothing. Either nobody's home, or nobody's checked the right room yet.

Mara: One team went looking for a third option. In archived data from the Arecibo telescope, collected before it collapsed in 2020, they found similar signals, much weaker. Their proposal: a magnetar, a super-magnetized, extremely dense star, beams out concentrated microwave energy, almost like a laser. That flare hits a cold hydrogen cloud and amplifies it enough to look, from Earth, like a blip from a distant civilization.

Eli: Their lead said most suspected human radio interference, but this explains it pretty well.

Mara: Two telescopes, a good explanation, he said, and still a certain amount of doubt. Which is where that 1975 researcher drew his blunt conclusion: no settlers here, no traces of their engineering in our solar system, so no extraterrestrials. In 2000, Peter Ward and Donald Brownlee offered a different reason for the emptiness, rooted in our own planet. Their Rare Earth hypothesis says simple microbial life might be widespread, but a complex biosphere like ours needs such an exacting combination of factors that it's rare. Microbes, plenty; anything like us, scarce.

Eli: So a wet planet in a nice orbit isn't enough.

Mara: Not by their reckoning. For about 80 percent of the time since life appeared here, Earth had only bacteria. Animal-like life took roughly 4 billion years. And they count protection as a requirement: gas giants keeping debris out of the inner solar system, cutting the odds of big impacts and mass extinctions.

Eli: If that's typical, a habitable planet and one that can call out are very different places.

Filters and Billions of Worlds

Mara: An economist, Robin Hanson, turned that kind of waiting into a warning. In 1998 he wrote, “There is a ‘great filter’ along the path between simple dead stuff and explosive life.” Picture the Great Filter as one step, somewhere between chemistry and a star-spanning civilization, that almost nothing gets through. As Hanson saw it, nothing in the whole past universe has made it all the way.

Eli: The unsettling part is not knowing which side of it we're on.

Mara: That's the hinge. If the hard step was early, say the origin of life, we're through it. If not, it lies ahead, and the pessimistic view, in Hanson's words, is that “the filter lies in our future, and we are doomed.” It could come from outside, an asteroid, or from within, all-out nuclear war, technological species reliably wiping themselves out before going interstellar.

Eli: A long way from one astronomer and a dish before dawn.

Mara: And when Drake chalked up his planet terms, nobody had found a single planet around another Sun-like star. Two Geneva astronomers did that in 1995. In 2009, NASA launched Kepler to hunt for Earth-like worlds. From the planets found so far, astronomers calculated that more than a fifth of Sun-like stars harbor habitable, Earthlike planets. Dimitar Sasselov reads it as a starting gun: “Now we know that exoplanets are common, and the search can begin in earnest.” Ward and Brownlee's reading still stands beside it: the right orbit is only the first of many unlikely conditions.

Eli: So modern exoplanet missions turned the early planetary variables of Drake's 1961 equation into measured astronomical realities. What's still unmeasured is whether anyone lives on them. Billions of candidate worlds, and not one confirmed transmission.

The Cosmic Haystack

Mara: So measure the silence itself. Picture the search as a haystack: every direction, every distance, every frequency, every moment, with a signal as the needle. That's the cosmic haystack problem. In 2018 Jason Wright and colleagues estimated how big that haystack is. In their units, it comes out around a six followed by 116 zeros, a number too big to picture, which is rather the point. Then they worked out how much of it every search so far had covered.

Eli: How much?

Mara: About four parts in ten billion. Jill Tarter had already pictured it in 2010: so little had been searched, it was like dipping a single glass into the ocean to see whether it contains fish.

Eli: So six decades of nothing.

Mara: And by the SETI Institute's count, only a few thousand stars have had a sensitive listen, over a small slice of frequencies. The search that was bad science in 1960 has barely begun.

Eli: The newer tools come back empty too, just more carefully. In 2025 researchers announced dimethyl sulfide, a compound ocean plankton make on Earth, in the atmosphere of K2-18 b, a planet circling another star. Other scientists quickly challenged it; the data didn't prove the gas was there. NASA says confirming life would take follow-up studies and several converging lines of evidence, with false positives ruled out.

Mara: A hint of life?

Eli: Then came 3I/ATLAS, an object from interstellar space. The SETI Institute's Allen Telescope Array was on it within a day of the announcement, listening for narrowband signals, sharp single-frequency tones nature isn't known to produce. It sifted through 211 signals of interest. None turned out artificial.

Mara: And an August 2026 review found no alien organism, fossil, biosignature or technosignature confirmed anywhere; humans are still the only civilization anyone's observed. The silence is real, Eli. So is how much of the sky nobody has listened to yet.

Alone or Unheard

Eli: So, the listener's question. Are we alone? Nobody knows, because no life beyond Earth has ever been verified. Drake's equation shows where the gap sits. Astronomers have pinned down its first three terms, the stars and planets, to some extent; the last four, life, intelligence, technology and lifespan, are still speculation. The mediocrity principle says that if Earth is typical, life on a suitable planet may be close to certain. But Earth is the only example there is.

Mara: And part of the silence already has an explanation: the haystack's barely touched.

Eli: Part of it. The rest hangs on Drake's last term, how long a civilization keeps transmitting. Adam Frank put it plainly: “We don't even know if it's possible to have a high-tech civilization that lasts more than a few centuries.” Woodruff Sullivan noted in 2016 that even a thousand civilizations in our galaxy, each lasting about as long as we've been around, roughly ten thousand years, would likely all be extinct already. That's the Great Filter, seen from the lifespan side.

Mara: How long anyone lasts, us included?

Eli: Then there are readings where someone's out there and quiet. Spreading through the galaxy may be too expensive. Earth may be deliberately isolated. Talking may be dangerous, so civilizations hide. In 1973 John Ball proposed “that they are deliberately avoiding interaction and that they have set aside the area in which we live as a zoo.”

Mara: For Jason Wright and Jill Tarter, the plainer reading: most of the ocean's untouched.

Eli: Drake started with two stars; now there are billions of planets, and a haystack barely touched. What would change the picture: a repeatable, narrowband signal, which one 2019 white paper said would make the interpretation “unambiguous and compelling.” A verified biosignature or fossil. A settled answer on the Wow! signal. Some measure of how long civilizations last, and whether the filter is behind us or still ahead.

Mara: A concept to dig into next is the Fermi paradox.

Eli: Follow science with us as astronomers probe whether anyone is out there.

Mara: Thanks for listening. I'm Mara.

Eli: And I'm Eli. Until next time.