Sagan Atom Cycle
On March 3rd, 1972, NASA launched Pioneer 10 and on April 6th, 1973, launched Pioneer 11. On the crafts, there's a plaque, on these plaques there is a pictoral example of humans and a measurement of earths location, relative to stars. But how do we tell the distance?
On September 5th, 1977, NASA launched Voyager 1 as an interstellar probe. On the craft there is a record made of gold. This record contains music, pictures, videos, animal sounds, and phrases in multiple languages. If discovered, the question was, how will an alien society understand any of this? On the back there are instructions and earth coordinates.
Carl Sagan had an answer. The most abbundent atom in the known universe is hydrogen. A time measurement that can be a distance measurement based on hydrogen atom transition cycles. From Earths coodinates to record player instructions, other than binary, hydrogen atom measurements could help convey the message.
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