Re: [math-fun] Mathematics of SETI protocols ?
Henry Baker <hbaker1@pipeline.com> wrote:
Tom Knight wrote:
I've always wondered why we think messages have to happen at time scales similar to ours.
Why couldn't a perfectly plausible alien civilization send messages at the rate of a bit per year, or a bit per century?
We have a very narrow view of what "short" or "long" time periods are.
Perhaps some aliens have been trying to communicate with use via ice ages -- e.g., 20,000 years per symbol -- or via sunspot cycles, and we just haven't been paying attention?
It seems unlikely that aliens who work that slowly would have had time to evolve already, given that the universe is only 13.8 billion years old. Of course they could send slowly even if it's not natural to them. QRSS (as radio amateurs call it) is a great way to send signals long distances with low powers. The slowest I've heard of is one bit per hour. A QRSS signal was successfully bounced off the moon despite having an absurdly low transmitter power of three milliwatts. Might aliens send quickly? Sure. Indeed, our 100 gigabit per second Ethernet would seem utterly inhuman to 19th century telegraphers, who averaged about 10 bits per second. A telegrapher patiently tapping away non-stop from the invention of the telegraph until the present would send less than a 100 gigabit Ethernet would send in a second. It would be possible to send at several speeds at once -- a self- similar fractal signal. If you're a real speed freak, see the YouTube video "Timelapse of the entire universe." 13.8 billion years compressed into 10 minutes. On that scale, dinosaurs evolved ten seconds ago and went extinct three seconds ago, the continents drift at hypersonic speeds, and civilization began less than half a millisecond ago.
Their (current) slow transmit speed might not be their fault. If they're located near to a very large black hole, their time gets slowed, way, way, down. Similarly, if they're moving near the speed of light -- to be expected from an advanced civilization -- even their gigabit ethernet will seem slow to us. At 08:12 PM 11/28/2018, Keith F. Lynch wrote:
Henry Baker <hbaker1@pipeline.com> wrote:
Tom Knight wrote:
I've always wondered why we think messages have to happen at time scales similar to ours.
Why couldn't a perfectly plausible alien civilization send messages at the rate of a bit per year, or a bit per century?
We have a very narrow view of what "short" or "long" time periods are.
Perhaps some aliens have been trying to communicate with use via ice ages -- e.g., 20,000 years per symbol -- or via sunspot cycles, and we just haven't been paying attention?
It seems unlikely that aliens who work that slowly would have had time to evolve already, given that the universe is only 13.8 billion years old.
Of course they could send slowly even if it's not natural to them. QRSS (as radio amateurs call it) is a great way to send signals long distances with low powers. The slowest I've heard of is one bit per hour. A QRSS signal was successfully bounced off the moon despite having an absurdly low transmitter power of three milliwatts.
Might aliens send quickly? Sure. Indeed, our 100 gigabit per second Ethernet would seem utterly inhuman to 19th century telegraphers, who averaged about 10 bits per second. A telegrapher patiently tapping away non-stop from the invention of the telegraph until the present would send less than a 100 gigabit Ethernet would send in a second.
It would be possible to send at several speeds at once -- a self- similar fractal signal.
If you're a real speed freak, see the YouTube video "Timelapse of the entire universe." 13.8 billion years compressed into 10 minutes. On that scale, dinosaurs evolved ten seconds ago and went extinct three seconds ago, the continents drift at hypersonic speeds, and civilization began less than half a millisecond ago.
participants (2)
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Henry Baker -
Keith F. Lynch