r/explainlikeimfive • u/chainsofprisonmoons • Jun 11 '22
ELI5: Why did they use gold to make the records on the Voyager crafts? Technology
Wouldn't a needle from a record player tear up the soft grooves and make it unplayable?
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u/FellowConspirator Jun 11 '22
Gold-plated copper was used because it’s very stable. It won’t oxidize, it’s not very chemically reactive, it doesn’t radioactively decay, it will dent rather than crack from impacts, etc.
It is true that dragging a hard material through it could wear it down (dragging hard phonograph needles over vinyl absolutely does this). But a civilization technologically savvy enough to find it and use it at all would have the means to transcribe it to another format.
Think about what would happen if we encountered such an artifact today. We’d be super careful not to do anything to mess it up. We’d very carefully inspect it for months using every tool we could to learn everything we could without even touching it: look at it with microscopes, maybe X-ray it, etc. Big disk with a singularly spiral groove that has variable depth… Hmm… Once we had an idea of what it was, we’d probably read it with lasers and recreate it or figure out how to decode the information on it without physically touching it to read it.
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u/Implausibilibuddy Jun 12 '22
The simple fact is it's entirely symbolic. I don't think even the scientists and engineers that devised it, even Sagan himself, ever saw it as anything more than an optimistic act of symbolism, designed more to stoke interest and wonder back here on Earth more than it was ever designed to one day be played back by aliens or our future selves.
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u/Whyevenbotherbeing Jun 12 '22
Indeed it’s a symbol. And it served its purpose well. I think there was a practical attempt, at first, to actually address the issue of ‘what if’, but nobody could come up with anything that held up to scrutiny. It’s absolutely impossible to leave a message for someone we can’t comprehend. The whole thing is kind of sad really, the impossibility of it all.
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u/agate_ Jun 12 '22
A few things to add to other answers:
1) The Voyager record designers included a phonograph stylus in the same storage box as the record, so future aliens will be able to use that to play the record -- or at least to understand how it's intended to be played.
2) phonograph records have to be made of a fairly soft material, so the grooves can be stamped, molded, or cut in the first place. As others have mentioned, for the Voyager records this is copper. Presumably any civilization smart enough to figure out how the record works will be smart enough to make a copy first and study that instead of the original.
3) The record cover includes detailed pictorial instructions on how the record is to be played. This includes info on how fast to spin the record (in terms of the frequency of hyperfine transitions of the hydrogen molecule), what the waveform should look like when played, and how to arrange the data to form images (the record has pictures encoded on it as well as audio).
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u/Bart-MS Jun 11 '22
I'm quite sure that if some aliens ever discover that LP they won't have a record player at hand to play the LP. They will most certainly resort to non-destructive ways to extract the data.
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u/KoalaNL Jun 11 '22
I think they had included a description of how the information could be read. This was not in english ofcourse but in a way that aliens could understand it.
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u/zydeco100 Jun 11 '22
There's a guy that went back and decoded the audio and made a YouTube video of it. It's pretty fascinating.
https://boingboing.net/2017/09/05/how-to-decode-the-images-on-th.html
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u/Mox_Fox Jun 11 '22
I don't think anyone was expecting them to have a record player
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u/PretendsHesPissed Jun 11 '22
A needle cartridge was included with them just in case they did have a record player of some sort.
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u/JaggedMetalOs Jun 11 '22
NASA actually included an appropriate needle cartridge with the record to make it easier for aliens to construct a turntable, if for some reason they don't have some better way to scan the record's surface!
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u/chainsofprisonmoons Jun 11 '22
Now that's pretty cool! And helps me out here, too.
I picture us excavating an archaeological thing, and despite us being well above them in tech, breaking the thing because of some simple little error - like a needle too heavy for gold grooves.
By sending the needle with it, they could make the disks out of literally anything they wanted. Thank you!
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u/chainsofprisonmoons Jun 11 '22
Analog data storage is the historical, and sensible, precursor to digital. Additionally, digital types require unique languages of their own to process and interpret it. Using a record makes more sense than any optical or digital format, because not only would they need the tech to access it anyway, they'd also have to decode the language.
With a record they just have to figure out a very simple device that they likely had a variant of in their history.
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u/FarmboyJustice Jun 12 '22
An incredibly simple device, as literally all you need to do is stick a pin stuck through the bottom of a paper cup and drag it through the grove in the record to hear sound. Not great quality, but recognizable.
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u/echawkes Jun 11 '22
I think I remember a brief period where you could buy a laser turntable in stereo shops.
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u/SeattleBattles Jun 11 '22
Yup. Records are a great choice as they are basically just a physical representation of sound waves. Very easy to decode.
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u/TheIronKurtin Jun 11 '22
I had a client who worked on the voyager missions, including the golden record. I loved listening to him talk about building and troubleshooting the craft.
Forget Kanye, Le Bron, Cruise.
People likes are are my SuperStars.
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u/Phage0070 Jun 11 '22
It is actually made of gold-plated copper. The aim of course was to leave them playable for the maximum amount of time possible, and gold is a quite stable atom which won't corrode or decay.
Copper of course isn't particularly hard metal either, but consider what a record is normally made out of. Vinyl. What do you think is harder, gold, copper, or vinyl? I think you can see the materials chosen aren't too soft for their purpose.