Episode Details

It is often assumed that space expansion by intelligent actors would be clearly visible on a cosmic scale. I have previously outlined some reasons to doubt this assumption and to treat quiet cosmic expansion as a plausible explanation for the observed cosmic silence (see also Freitas, 1983; Fogg, 1987; Kent, 2011).

My aim in this essay is to present some additional considerations in favor of quiet cosmic expansion based on prudent cooperation and risks of ruin. Although these considerations are speculative, I believe they add further theoretical support to the plausibility of quiet cosmic expansion as an explanation of the Fermi paradox, and suggest that this picture should not be dismissed out of hand.

There is a broad spectrum of quiet expansionist hypotheses. My main focus here is on a cooperative version of quiet expansion, in which advanced civilizations avoid loud cosmic activity in part because they treat silence as a potentially prudent equilibrium or norm. Yet many of the considerations I review below also support quiet expansion more generally, including less cooperative or merely risk-averse versions of quiet expansion.

Outline of the cooperative silence hypothesis

The cooperative silence hypothesis explored here broadly involves the following premises:

• [...]

---

Outline:

(01:21) Outline of the cooperative silence hypothesis

(04:00) The quiet expansionist spectrum: From dark forest to cooperative silence

(06:22) Toy model

(09:01) Why quiet expansion is plausible

(09:33) A silent universe is evidence of what?

(11:42) Going loud would be evidence of what?

(12:30) Signaling strategic similarity

(13:27) Strong aversion to risks of ruin

(15:30) Avoiding irreversible signals and commitments

(16:23) Asymmetric error costs

(17:03) Long exploration

(18:34) Avoiding cosmic conflict

(22:39) Potentially limited gains from going loud

(25:02) Evidential cooperation in large worlds

(26:35) Selection effects

(29:27) Convergence is not required

(31:32) SIA supports cooperative convergence

(34:47) The observed evidence favors cooperative silence over dark forest

(35:38) Objections

(41:53) Practical implications

(46:52) Acknowledgments

(47:06) References

The original text contained 6 footnotes which were omitted from this narration.

---

First published:
September 25th, 2026

Source:
https://forum.effectivealtruism.org/posts/Tt3dTpkPjqQbAdSgL/the-cooperative-silence-hypothesis

---

Narrated by TYPE III AUDIO.

---

Images from the article:

---

Listen Now