system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can a piece of vinyl be carved in a way that perfectly mimics the sound of an individual person's voice?

I can sort of understand records mimicing the sound of instruments, but voices are so unique, how did we ever figure out the exact carving of a piece of vinyl that when you drag a needle across it, you'll get the same sound as x or y person's voice exactly?
gpt
The sound is what carves the vinyl. 

When recording, in the original technology, the sound vibrates a needle, which is dragged along the spinning disc to carve the grooves. When the record is put on a player, it spins and the needle is dragged across it. The needle is pushed along the ridges of the record, causing it to vibrate in exactly the same way as the one that carved it. That vibration goes up the needle as a sound, gets amplified, and there's your recorded sound. 

Sure, in theory, one could map exactly how a particular sound would cause the needle to move, and thus what exact shape of ridges would create that sound when it's played, but it's so complex to do something like that, it'd be easier to literally invent digital sound design and make the sound ypu want happen that way. Simpler to just tryst physics to take care of it for you. It's just a matter of running the same physical process in reverse. 

Side fact: it's actually kind of a big deal in physics that most of the laws of physics run exactly the same backwards as they do forwards. There are a few specific things that don't go like that, and that makes them really important in thermodynamics, relativity, quantum mechanics, etc.