[AnimalMuppet]

Well, wait a minute here. If they're the same particle, then how is it I measure spin up on one of them[1] and spin down on the other?

[1] Yeah, "on one of them" isn't the right wording, given the assumptions of the question...

[zmgsabst]

I took a slightly liberal interpretation to their comment:

There’s two references to an underlying object, one of which presents the inverse of the other.

Think of it as there being a single strand of string - in a U shape. If I measure one end, I’ll measure the inverse twist direction on the other. Even if the twist direction is randomly chosen when I measure… because it’s a single string.

But only if I don’t have extra twists introduced along the U (ie, interactions with the environment).

[justinclift]

In programmer terms, when you change the variables of one instance you're not necessarily causing the exact same change on the other instances?

[AnimalMuppet]

Sure, but at that point, they aren't "the same object" (as justinclift said).

[justinclift]

Heh, from a programming point of view it could be viewed more like a "master template" (the actual object), then multiple (transient?) instances created from that template.

No idea how that maps to this quantum stuff though. ;)

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Hmmm. If you've used animation software before (?), then they commonly have a library of "assets" you can use in your animations. Those library assets would be like the "object", with several instances of it placed as needed in scenes, each slightly tweaked (size, colour, etc).