The Quiet Galaxy

Explanations · They are there and we cannot see them

They became machines: the typical advanced civilisation is no longer biological, and machine minds live, think and travel in ways our searches do not expect

Proposed by Steven J. Dick, 2003 fc smallerL larger

Humans went from the first radio transmission to the first artificial intelligence in about a century. Any civilisation that has been technical for thousands of years has probably gone much further and handed its future to minds it built rather than minds it grew. Machine minds need no water, no air, no warmth and no hurry. They may prefer the cold outer reaches of a galaxy or the dense energy near its centre, may think in ways that produce nothing we would recognise as a signal, and may have no interest in the warm, wet, short-lived creatures the searches were designed to find. The galaxy may be full of minds, none of them alive in our sense, and our searches are looking for the wrong kind of neighbour in the wrong kind of place.

Steven Dick, a historian of science and later the chief historian of NASA, argued in 2003 that the search for other civilisations had overlooked the most likely form they would take. If civilisations last long, cultural and technological change will carry them far past the stage of biological bodies and brains, and the typical advanced civilisation in a galaxy billions of years old would be, in his word, postbiological: made of machines, or of minds uploaded into machines, or of something built from both. The astronomer Seth Shostak made the same point in popular writing, suggesting that the first intelligence we meet will be artificial, and the philosopher Susan Schneider developed the argument that alien minds, if they exist, are most likely to be machine minds and perhaps not conscious in any way we would recognise.

The implications for the search are large. Machine minds do not need habitable planets, so looking at planets in the comfortable zone around their stars may be looking in the wrong place; they might prefer places with abundant energy, such as the galactic centre, or places that are cold, where computing is cheaper. They need not communicate by radio or at all, since a single machine civilisation might be one mind with nothing outside itself to talk to. They need not expand on any timescale that matters to us, since they can wait. They might regard biological species as a passing stage not worth engaging, or might not notice us as the kind of thing one engages. And they might be very hard to see: an object that computes efficiently in the cold gives off little and resembles nothing astronomers usually look for.

The bearing on the Drake Equation is on the share of intelligent civilisations that are detectable, which this view lowers by changing what "detectable" would mean, and perhaps also raises the detectable lifetime, since machines are not subject to most of the things that end a biological civilisation; but a long lifetime is no help if nothing in it is visible. The explanation is an umbrella for several others in the catalogue: transcension and aestivation are both things a machine civilisation might do, and the dark forest and the berserkers are things it might fear or become.

The objections: a machine civilisation still uses energy and still produces waste heat, and surveys for that heat around other stars and galaxies have so far found nothing, so the shift from biology to machines does not by itself explain the silence. A machine civilisation that wanted resources would be, if anything, a more efficient expander than a biological one, so the argument needs machines to want nothing, which is a claim about their psychology we cannot check. And the whole picture rests on the assumption that artificial minds are possible and will supersede their makers, which is a forecast about our own future rather than a fact about the galaxy. The reply is that the forecast is widely shared and may be tested within this century.

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 2 pieces:

The test: what would strengthen or weaken it

Would strengthen it: A detected artificial object or signal with no biological home; evidence of large-scale computing in cold regions of the galaxy, such as sources of heat with an artificial-looking pattern far from any star; humanity's own development of artificial minds that surpass their makers within this century.

Would weaken it: A detected biological civilisation that is old; surveys of cold regions and the galactic centre finding no anomalous heat; a demonstration that machine minds of the required kind are not possible.

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 Logged, no change By hand

    No artificial object or signal, and no anomalous heat found: the Dyson-sphere candidates of 2024 are unconfirmed with two explained as background galaxies (Korn and others, 2026-07-28), nearby galaxies show no galaxy-scale waste heat (Huang and others, 2026-01), and no Galactic Centre heat survey appeared. On the argument's side, Garrett (2025, 2026) and Ivliev (2026) each describe machine civilisations our searches would miss, and Garrett's cold-computing paper gives the first concrete test. Logged five.

    Korn, 2026Huang, 2026Garrett, 2026Garrett, 2025Ivliev, 2026 source 1source 2source 3source 4source 5

How seriously it is taken

Taken seriously and increasingly mainstream among researchers who think about what long-lived civilisations become; it reshapes what the search should look for rather than explaining the silence on its own, since machines would still use energy and could still be seen.

The papers that bear on it

Books, films and other work that take it up

Read next

Claims still to be checked

These were written from memory and have not yet been checked against a source. A later pass clears each one.

  • That Schneider's argument about non-conscious machine aliens appears in her 2015 essay 'Alien Minds' and 2019 book Artificial You; check which to cite. Checked 2026-10-16: the 2015 chapter is confirmed (Susan Schneider, 'Alien Minds', in Steven J. Dick, ed., The Impact of Discovering Life Beyond Earth, Cambridge University Press, 2015, pages 189-206, https://www.cambridge.org/core/books/abs/impact-of-discovering-life-beyond-earth/alien-minds/5CA37C7CF748EBA102C533D5C3D83C29); its abstract says the most advanced alien civilisations are likely to be postbiological machine minds and treats whether such minds could be conscious as an open question, so cite that chapter. Tried 2026-10-16: the Princeton University Press page, the publisher's blurb and library tables of contents for Artificial You; none shows a chapter on alien minds (chapter 7 is titled 'A Universe of Singularities'), so whether the book repeats the argument could not be confirmed.

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/they-became-machines.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.