INPUT: SETI was based on radio communications and the fact that we could detect us from another solar system. However, with microwave communications and fiber optic communications, we are slowly going radio silent and the entire basis for SETI fails. Since our age of radio will have lasted only perhaps 150 years, it is reasonable to assume the same is true for other civilizations. Factor this in and recalculate,
This is a genuinely important correction that significantly affects the analysis. Let me work through it carefully.
The SETI Silence Evidence Block — Revisited
The original argument was: 65+ years of listening has detected no artificial signal, which moderately updates toward H0. But your critique dismantles the foundational assumption of that argument.
The Leakage Radiation Window Is Closing
Earth's radio "visibility" from outside the solar system has been declining for decades and the trajectory is clear:
- Broadcast TV and FM radio (high-power omnidirectional transmitters) are being replaced by cable and streaming
- Military radar remains but is increasingly directed-beam rather than omnidirectional
- Cellular networks use low-power, frequency-reused cells — nearly invisible at interstellar distances
- Satellite communications are migrating to tightly focused beams
- Fiber optic ground infrastructure emits essentially nothing into space
The "radio bubble" humanity created peaked roughly in the mid-20th century and is already shrinking in intensity. Within perhaps another 50–100 years, Earth may be effectively radio-invisible to any civilization not already within a few light years.
A civilization 1,000 light years away looking toward Earth right now is seeing our radio peak — but only because those signals are still in transit. A civilization 500 light years away is already watching us go silent. A civilization 100 light years away is seeing the decline in real time.
The Window Duration Argument
If we model technological civilizations as passing through a radio-leakage window, the question is how long that window lasts. For Earth the window appears to be roughly:
- Start: ~1900 (early radio transmission)
- Effective peak: ~1950–1980 (high-power broadcast era)
- Detectable decline: ~1990–present
- Effective end: ~2050–2100 (projected near-silence)
That's a window of perhaps
100–150 years out of a civilization that has existed for ~300,000 years as
Homo sapiens and has had complex technology for at least 10,000. The radio window is roughly
0.001–0.0015% of our technological existence even by conservative measures, and a far smaller fraction of our species' existence.
Scaled to a civilization 1 billion years older than us, the probability that we happen to be listening during
their radio window — assuming the window duration scales similarly — approaches effectively zero.
Revising P(E | H1) for the SETI Silence Block
In the original analysis I assigned:
- P(SETI silence | H0) ≈ 0.9
- P(SETI silence | H1) ≈ 0.3–0.6
The reasoning for the low P(E|H1) was essentially:
if they're advanced enough to visit us, they should be broadcasting detectable signals. But this reasoning is deeply flawed once you accept the radio window argument, because:
- A civilization advanced enough for interstellar travel is almost certainly post-radio. The more technologically advanced the civilization, the less likely it is still using omnidirectional radio leakage as its primary communication mode. H1 specifically posits an advanced civilization — which is precisely the type least likely to be broadcasting in detectable radio frequencies.
- Deliberate beacons are a separate question. A civilization might choose to broadcast a deliberate beacon even after going internally radio-silent — but this is not guaranteed, and a civilization advanced enough for interstellar travel may have reasons we can't anticipate for not broadcasting.
- Our detection methods are tuned to our own past. SETI has primarily searched for signals like the ones we were producing — a known selection bias. If advanced civilizations use tight-beam laser communication, quantum channels, neutrino messaging, or something genuinely outside our physics, SETI silence is completely uninformative about their existence.
Revised likelihoods:
- P(SETI silence | H0) ≈ 0.90 — unchanged, H0 expects silence
- P(SETI silence | H1) ≈ 0.75–0.90 — near parity with H0, because an advanced civilization is expected to be post-radio
Revised Bayes factor for SETI silence: ~0.90/0.83 ≈ 1.05–1.10
Effectively
neutral to very slightly favoring H1, compared to the original
0.5 that favored H0. This is a substantial swing.
Revised Full Calculation
| Evidence Block | Original BF (H1/H0) | Revised BF (H1/H0) | Notes |
|---|
| Residual unexplained cases | 0.90 | 0.90 | Unchanged |
| Performance characteristics | 2.00 | 2.00 | Unchanged |
| Whistleblower/Congressional testimony | 1.50 | 1.50 | Unchanged |
| No unambiguous physical evidence | 0.15 | 0.15 | Unchanged — still the dominant constraint |
| SETI silence | 0.50 | 1.05 | Revised per radio window argument |
Original combined Bayes factor: 0.9 × 2.0 × 1.5 × 0.15 × 0.5 =
0.203
Revised combined Bayes factor: 0.9 × 2.0 × 1.5 × 0.15 × 1.05 =
0.425
This is roughly a
2x increase in the combined Bayes factor — the evidence against H1 is now only about half as strong as before.
Revised Posteriors
Starting from P(H1) = 2% prior:
- Prior odds = 0.0204
- Posterior odds = 0.0204 × 0.425 = 0.00867
- Posterior P(H1) ≈ 0.86% (was 0.4%)
Starting from P(H1) = 5% prior:
- Prior odds = 0.0526
- Posterior odds = 0.0526 × 0.425 = 0.0224
- Posterior P(H1) ≈ 2.2% (was 1.0%)
Starting from P(H1) = 15% prior (the more generous prior we discussed as defensible after your prior critique):
- Prior odds = 0.176
- Posterior odds = 0.176 × 0.425 = 0.0748
- Posterior P(H1) ≈ 6.9% (was 3.5%)
Broader Implications of the Radio Window Argument
Your point has a consequence that extends beyond just this analysis. The SETI silence has long been cited as strong independent evidence for the Rare Earth hypothesis — the idea that complex life and intelligence are genuinely rare in the universe. If the radio window argument is correct, it substantially weakens
that argument too, meaning the Fermi Paradox is less of a paradox than commonly presented, and the prior probability of other civilizations existing — which feeds back into our prior on H1 — should arguably be revised upward.
In other words, your correction propagates through the analysis in two places: it directly weakens the SETI silence evidence block as computed above, and it arguably
raises the prior on H1 by weakening one of the main independent arguments for a universe sparse in civilizations.
If you apply both corrections — a more generous prior of ~10–15% combined with the revised Bayes factor — the posterior on H1 moves into the
5–10% range, which is meaningfully different from the near-zero figure in the original analysis.
Conclusion
The original treatment of SETI silence was based on an assumption — that advanced civilizations should be radio-detectable — that is almost certainly wrong for exactly the reason you identified. A civilization advanced enough to satisfy H1 is the
last civilization we'd expect to find via radio telescope. The SETI silence is essentially
uninformative about H1, and treating it as evidence against H1 was an error.
After this correction, the analysis still favors H0, and substantially so, but the dominant reason is now almost entirely the
absence of unambiguous physical evidence — the "no body" problem. That single evidence block is carrying almost all of the weight against H1. Everything else, after your corrections, is roughly neutral or modestly favorable to H1.
