Evidence
fact ⇄ what kind of claim · live
2380 MHz, 450 kW, 10 bits/s, 10 Hz FSK, 167.9 s, once
16 Nov 1974 · the transmission record, used as written
MEASURED
The 1679 bits themselves, unedited
the transmitted artifact · 23 × 73 renders the figures
MEASURED
Written by Drake with Sagan and colleagues, as a demonstration
the published record on intent, quoted rather than interpreted
REPORTED
1961: 551 bits to the Green Bank attendees, one solver
Drake's cryptogram · Barney Oliver replied with a martini glass
REPORTED
Readable to ~93 ly, detectable to ~3,100 ly
textbook link budget · η 0.35, Tsys 25 K, 10 Hz bin, SNR 10 / 15
MODELLED
The wavefront is ~52 ly out; arrival ≈ 26,975 AD
one light year per year since November 1974 · arithmetic
MEASURED
Chilbolton 2001: an edited Arecibo message in a field
SETI Institute: no evidence of an other-than-earthly origin
REPORTED
Whether 167.9 seconds was a message or a monument is a reading
the bench computes the budget; the file stays open
READING
View
The send1974, in real time
The decodefold it yourself
The composeyour 1679 bits
The file1961-2020
…
The fold
17ragged
23the picture
41noise
73the other
Your message
Start from 1974edit a copy
Blank grid23 × 73, empty
▶ Transmit mine instead
Where to, and who is listening
Proxima4.2 ly
TRAPPIST40.7
Kepler-4521.8k
M1325k
Green Bank100 m
Arecibo305 m
FAST500 m
Playback & layers
Playback167.9 real seconds, sped up
Rate
1× real 8× 32×
Audiothe FSK at an audible pitch
Waterfallwhat a receiver would draw
Journey stripwhere the wavefront is
Bits in the beamthe ones and zeros, climbing
Section coloursdecode view
Section labelsdecode view
Readout · live from the link budget
Effective radiated
—
Beam width
—
SNR per bit at target
—
Readable to
—
Detectable to
—
Arrival
—
Earliest reply
—
…
What is measured vs modelled here
Measured: the 1679 bits, the transmitter's power and frequency, the 10 bits per second and the 10 Hz shift, the 167.9-second airtime, the wavefront's distance today. Reported: the design team and the stated intent, Drake's 1961 cryptogram and its single solver, Ryle's objection, the Chilbolton formation and the SETI Institute's response. Modelled: every reach number on this bench, from stated assumptions. Reading: whether a single 167.9-second pass at a target 25,000 light years away was a message or a monument.
The link budget, in full
Transmit gain from the aperture, G = η(πD/λ)² with η = 0.35 and D = 305 m at λ = 12.6 cm, giving 73.1 dBi and an EIRP of 9.1 TW. Received flux falls as 1/d². A receiver of effective area A sees S·A watts against a noise power kTsys B, with Tsys = 25 K and B = 10 Hz, the bit bandwidth. Reading the raster is taken as SNR 10 per bit; detecting the carrier is taken as coherent integration over the whole 167.9 s against a threshold of 15. Those four assumptions are the only free parameters, they are stated on the face of the instrument, and moving them moves the ranges as the square root, which is why no plausible receiver reaches M13.
Where this drawing takes liberties
The beam cone is drawn orders of magnitude wider than 1.7 arcminutes, or it would be invisible. The star field and M13's stars are procedural, not a catalogue. The audio plays the FSK at 660 and 880 Hz rather than 10 Hz apart at 2380 MHz, because ears. The journey strip is logarithmic. The bits, the transmitter numbers, the section contents and every quotation take no liberties.
▶ Story · 15 chapters
⟳ Reset