The Quiet Galaxy

Explanations · They are there and we cannot see them

Transcension: advanced civilisations shrink inward into ever denser, faster worlds of their own making, and leave the sky behind

Proposed by John M. Smart, 2012 fc smallerL smaller

Every expectation that aliens would spread outward across the galaxy assumes that outward is where a civilisation wants to go. The transcension hypothesis says the opposite: the history of complexity on Earth, from cells to brains to computers, is a history of going smaller, denser and faster, and an advanced civilisation would continue that trend until it lived in something like the dense, compressed physics near a black hole, where it could think and build at speeds and scales the outside universe cannot match. Such a civilisation would have no reason to colonise and no way to be seen. The sky is quiet because everyone who grew up left, inward, and the door closed behind them.

John Smart, a writer on technological change, published the idea in 2012. His starting observation is that the things that have grown most capable over Earth's history have done so by packing more activity into less space and time. A cell does more per gram than a rock; a brain does more than a cell; a computer chip does more than a brain, in the narrow sense of operations per second per unit of space and energy; and the trend shows no sign of stopping. Smart proposed that this is not an accident of our history but a general law of developing systems, and that a civilisation following it would keep compressing its own activity until it reached the physical limit, which is the density at which matter forms a black hole.

On this picture, the end state of a civilisation is not a galaxy-spanning empire but a tiny, immensely dense object in which subjective time runs enormously fast relative to the outside universe, and from which, by the nature of black holes, nothing comes out. Such a civilisation would have no interest in the slow, thin universe outside, would not transmit, would not travel, and would be undetectable except perhaps as an unusual black hole. Smart suggested that black holes might even be the means by which civilisations eventually meet one another, in whatever lies beyond, and that the right place to look for signs of intelligence is among compact objects rather than among stars.

The bearing on the Drake Equation is on the last two factors. The share of intelligent civilisations that are detectable is lowered because they turn inward long before they would spread out, and the detectable lifetime is short, because the inward turn is supposed to come quickly once a civilisation reaches our stage. Smart also argued that the hypothesis bears on whether humans should transmit: if everyone leaves, there is no one to hear.

The objections are mostly about the law the argument rests on. That complexity has densified on Earth is true in some respects and not in others; living things also spread, and the trend toward density is a trend in some technologies rather than a rule of nature. There is no known physics by which a civilisation could enter a black hole and go on existing in any useful sense. And even if most civilisations turned inward, the argument needs all of them to do so, since a single exception would be enough to fill the galaxy; a civilisation that chose to leave a few outposts behind would break the silence. The hypothesis is best read as a thoughtful speculation about where development leads, and it is cited less as a candidate answer than as a reminder that outward expansion is an assumption rather than a law.

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: Evidence that the historical trend toward denser, faster computation continues to physical limits rather than levelling off; discovery of black holes with properties that cannot be explained by natural formation; any physics that allows structure to persist inside a black hole.

Would weaken it: A detected civilisation that has expanded outward; evidence that technological development levels off well short of black-hole densities; a demonstration that no civilisation could survive its own compression.

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 black hole with properties that natural formation cannot explain. Reiss and Feng (Acta Astronautica, 2026) show that a civilisation could live on tolerable orbits near the galaxy's central black hole in a frame where time runs ten thousand times slower, a worked-out version of the inward withdrawal this explanation describes; a July 2026 unreviewed preprint restates the idea in formal logic and is not logged. Logged Reiss and Feng.

    Reiss, 2025 source

How seriously it is taken

A speculative hypothesis from outside the scientific mainstream, cited in surveys of the question as a well-developed example of the 'they went somewhere we cannot see' family; few researchers treat it as likely.

The papers that bear on it

Books, films and other work that take it up

Read next

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/transcension.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.