The Quiet Galaxy

Explanations · They are there and we cannot see them

Everyone listens and nobody transmits: if every civilisation makes the same cautious choice we have made, the galaxy is full of ears and empty of voices

Proposed by Alexander Zaitsev, 2006 fc smaller

Humanity has spent sixty years listening for signals from other civilisations and almost no effort sending any; the handful of deliberate messages ever transmitted were brief, from the 1974 Arecibo message of under three minutes to a 2008 transmission of about four and a half hours. The reasons are familiar: sending is expensive, the reply would take centuries, and some people think announcing ourselves is dangerous. If every civilisation reasons the same way, every one of them is sitting in silence waiting for someone else to speak first. The Russian radio astronomer Alexander Zaitsev called this the SETI paradox, after the usual name for the search (SETI, the search for extraterrestrial intelligence): a search that assumes others transmit, run by a species that does not. The silence would then be a coordination failure on a galactic scale.

Alexander Zaitsev was one of the few people who ever sent deliberate messages toward other stars. The messages went out from the large radar dish at Yevpatoria in Crimea in 1999, 2001, 2003 and 2008; he supervised the 1999 and 2003 transmissions, helped design the 2001 teenagers' message, and advised on the 2008 one. He was also the sharpest critic of the asymmetry at the heart of the search. In a 2006 paper he pointed out that the search for extraterrestrial intelligence rests on an assumption its own practitioners decline to satisfy: that somewhere out there a civilisation has decided to transmit, steadily and strongly, for long enough to be found. Humanity, which has the means, has chosen not to, for reasons that range from cost to caution to the view that the decision should not be made by a few astronomers. If those reasons are good, they are good for everyone, and a galaxy of civilisations each as sensible as ours would be entirely silent while every one of them listened.

The argument is a cousin of the dark forest and the zoo but needs neither fear nor policy. It needs only that transmitting is a cost with no return within any planner's horizon, which is simply true: a message to a star a thousand light-years away gets a reply, at best, two thousand years later. Institutions do not fund projects with two-thousand-year payoffs. Private individuals occasionally do, which is why the few messages that have been sent were sent by enthusiasts, and why they were short.

The bearing on the Drake Equation is on the share of intelligent civilisations that are detectable, which this view lowers for the whole class of civilisations that are at or near our own level: they do not transmit on purpose, and the accidental leakage from their broadcasting is weak and brief. It makes no claim about civilisations far older than ours, which might have other reasons or none.

The objections: leakage is not nothing, and a civilisation a few decades ahead of us might be loud by accident in ways we would catch, though Earth's own leakage is falling as broadcasting moves to cables and aimed beams; a civilisation that lasts a long time will eventually have members who transmit, since humanity already has; and the argument explains the absence of deliberate beacons but not the absence of settlement, which was Hart's point and which no choice about transmitting affects. Zaitsev's reply was practical: if the silence is a coordination problem, the way to find out is to transmit, and he did. The debate over whether humanity should, which goes by the name of active SETI or messaging to extraterrestrial intelligence, continues, and this explanation is one of the main arguments on the side of sending.

What it says about the equation

Every explanation is a claim about one or more of the seven pieces that are multiplied to give the number of detectable civilisations. This one bears on 1 piece:

The test: what would strengthen or weaken it

Would strengthen it: A detected civilisation found by its faint leakage rather than by a beacon, suggesting that nobody transmits on purpose; a survey of Earth's own detectability showing that our leakage would be invisible from the nearest stars, which would make the same true of others.

Would weaken it: Detection of a deliberate beacon; evidence that civilisations generally expand and settle other stars, which would make their silence in the radio bands beside the point; a strong case that long-lived civilisations eventually transmit.

These two lines are what the record is read against when a new paper or discovery is logged. A result of the kind named here, published with its evidence, is what would settle it; a press claim on its own settles nothing.

The last reading

Once a week the records are read against the news, each against the test above. Open a line to see what that week held. Every reading ever made of this record is on the reading page.

  • 2026-10-16 Nothing new By hand

    No new study of Earth's own detectability since the 2023 finding that mobile-tower leakage would be invisible within ten light-years, no deliberate beacon detected, and no new transmission from Earth announced.

How seriously it is taken

Widely acknowledged as a real asymmetry in the search, and one of the standing arguments in the debate over whether humanity should transmit; as an explanation of the silence it is considered partial, since it says nothing about settlement or about civilisations much older than ours.

The papers that bear on it

Books, films and other work that take it up

  • Fiasco 1986 Book · Stanisław Lem

Read next

Notes

Checked 2026-10-16. Borne out: Zaitsev, 'The SETI Paradox', arXiv:physics/0611283, submitted 2006-11-29; its abstract says people seek signals yet resist sending them, and that if this is typical the search is pointless (https://arxiv.org/abs/physics/0611283). The Yevpatoria dish (RT-70) sent Cosmic Call in 1999 and 2003 (https://en.wikipedia.org/wiki/Cosmic_Call), the Teen Age Message in August to September 2001 (https://en.wikipedia.org/wiki/Teen_Age_Message) and A Message From Earth on 2008-10-09 (https://www.universetoday.com/19335/messages-from-earth-beamed-to-alien-world). Corrected: the page said Zaitsev sent all four; sources say he supervised the 1999 and 2003 transmissions (https://en.wikipedia.org/wiki/Alexander_Zaitsev_(scientist)), proposed the structure of the 2001 message, and was a consultant on the 2008 one, so the body now says that. The claim that all deliberate messages ever sent add up to a few hours could not be confirmed and looks too low: the 2008 message alone lasted about four and a half hours and Cosmic Call 2 is listed at about 12 hours (Wikipedia, whose figures do not quite match its own stated bit rates). The summary now gives only the two durations that sources support: the 1974 Arecibo message under three minutes (https://en.wikipedia.org/wiki/Arecibo_message) and the 2008 message about four and a half hours. Not checked: that Zaitsev answered the silence problem by transmitting, which the last paragraph of the body states.

Think this page gets the explanation wrong, or misses an objection? Say so, or read how disagreement gets folded in. The record itself is data/explanations/everyone-listens-nobody-transmits.toml in the public repository. This page's address will never change; if the explanation is ever retired, the address will say what replaced it.