Hyperfine Exploration, 2021
"The Pioneer plaques are a pair of gold-anodized aluminum plaques that were placed on board the 1972 Pioneer 10 and 1973 Pioneer 11 spacecraft, featuring a pictorial message, in case either Pioneer 10 or 11 is intercepted by intelligent extraterrestrial life. The plaques show the nude figures of a human male and female along with several symbols that are designed to provide information about the origin of the spacecraft."
These images explore a deconstructed Hyperfine Structure, which is a schematic diagram that can be found engraved onto a plaque aboard both Pioneer 10 and 11. It fascinated me throughout my last year of university, as I completed my dissertation on the design and creation of these interstellar messages.
This symbol represents a spin-flip transition of a hydrogen atom's electron. This electron spin-flip occurs at an energy frequency of about 1420.405 MHz. Light at this frequency has a vacuum wavelength of 21.106cm. The small dash underneath the horizontal line (hydrogen line) declares this value as the specified unit of length for the whole pioneer plaque. Every other diagram, the man, woman, sun and pulsars, spacecraft diagram and planetary diagrams all have measurements in binary that are converted using this 'key', the hydrogen line.
The designers of this message believed that hydrogen being the most abundant element in the universe (at an approximated 75% of all universal matter), would make it a steadfast candidate for extraterrestrial study, if such study occurs. Any civilisation with nascent scientific technology and understanding would most likely have intensely studied hydrogen, and discovered its electron spin-flip. They believed it could then be interpreted and understood, and that this interstellar postcard would then have its own sort of postcode, its own interstellar postcode.