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This 21-centimeter transition was chosen by the designers of the Pioneer plaques (https://en.wikipedia.org/wiki/Pioneer_plaque https://en.wikipedia.org/wiki/Pio
by mjd 1y ago
This 21-centimeter transition was chosen by the designers of the Pioneer plaques (https://en.wikipedia.org/wiki/Pioneer_plaque https://en.wikipedia.org/wiki/Pioneer_plaque) to explain to any alien readers how big we are. At top left is a cartoon of two hydrogen nuclei in opposite spin orientations, and a ruler in between them marked "1". Over on the far right you can see another ruler that measures the height of the female figure, marked with binary numeral "8" ("|---") to indicate that she is approximately 8×21 = 168 cm tall.
- arghwhat 1y agoIf only we could somehow share a physical entity of known dimensions to reference together with the drawing so that we did not need to use a physics riddle to indicate scale...
- mjd 1y agoWe did that too. There is a cartoon of Pioneer itself, drawn to the same scale.
- arghwhat 1y ago(I was sarcastically pointing to the plaque itself, a physical entity of a well known size to anyone capable of observing the drawing on it, unlike the space craft or physics riddles.)
- aylmao 1y agoUnsure what the tone of this message is, so I don't know if you're aware, but that's included too: > Behind the figures of the human beings, the silhouette of the Pioneer spacecraft is shown in the same scale so that the size of the human beings can be deduced by measuring the spacecraft. It's good to have redundancy, not just so someone interpreting the plaque can confirm their hypothesis, but also in case one of the messages fail. In this case, the spacecraft could break, but we can assume quantum transitions will always be observable. [1] https://en.wikipedia.org/wiki/Pioneer_plaque https://en.wikipedia.org/wiki/Pioneer_plaque
- arghwhat 1y agoI sarcastically referenced the plaque itself, which is a convenient disc of a known size to anyone observing the drawing, unlike the space craft or physics riddles. Using quantum transitions is quite ridiculous in my opinion due to requiring not only the observer to have a perfectly compatible understanding of physics (even a more advanced understanding might not be compatible - maybe they don't categorize elements by electrons, or even treat elemental particles as a quantifiable entity), combined with the sheer number of deductions required to understand what was meant with two circles and a few lines. I doubt we would ever have decoded this had we been the recipient rather than author, and that's with a perfectly compatible understanding of physics.
- spullara 1y agoDo you think that physics is somehow subjective? We absolutely would have decoded the message.
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- cuttothechase 1y agoOur understanding evolves, course corrects, spins off etc., we can use some static value as purported from the dark ages or by newtonian or later einstenian points of view. They all are measurably correct for the problems that they are trying to solve for the people who lived during those times. A million years from now would these values still be relevant or be considered as having the same value of importance or will they be replaced by even more finer and precise and contextually different values that could be more precise and more accurate etc.,
- arghwhat 1y agoIndeed. Say, maybe a civilization didn't start out with trying to build the world of particles of progressively finer size, but started directly with a model of fields, waves and charges and therefore never had a concept of a discrete elemental particle, and in turn a system built around that to categorize elements. Or to them, an atom is as large an arbitrary macro structure as proteins are to us, and so they would never consider two empty circles with a single line to represent something so big and chaotic. Or maybe they had the crazy idea of building everything of vibrating strings! Who knows what the abstractions and approximations would be when the foundation of it all isn't "getting hit on the head by an apple".
- linschn 1y agoThe plaque also provided a drawing of the probe itself next to the two human figured, at scale.
- pdabbadabba 1y agoYeah. It would be pretty funny if an alien reader of the plaque concluded that 1 refers to the actual length of the line between the two circle thingies and concluded, therefore, that we're only a few cm tall.
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- Pixelbrick 1y agoBanana!
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- RcouF1uZ4gsC 1y agoThey could have also used a 21cm length more directly for the male figure, but they did not.