It’s just a thought experiment, but maybe somebody finds it interesting.
What if coins would expire after a time, if not used?
I understand there’s not necessarily a need for reclaiming “lost coins” (or so I heard), and having to use them just to keep them alive is sure an inconvenience (not as much as it first sounds, but more on that in a bit.) Anyway, here’s the idea.
Let’s say, a coin expires 4 (1, 2, 5, 10, 20, …?) years after it was last used. In effect, if somebody wants to pay with a coin that they received more than 4 years ago, it’s not going to be accepted.
When a coin is divided, the parts will expire after half the time the full coin would, if a half is divided then its part after a quarter of the time, and so on.
For additional magic, the expiry time could depend on something that is tied to a coin’s market value. For example, if the available supply is high, the expiry time goes down, but if it’s low, the time goes up. If set properly, large value denominations (full coins, half coins, …) would live long enough to be convenient for savings, while smaller denominations (16th coins, 32nd coins, …) would serve as change.
A hidden benefit of such a system would be that smaller denominations (as they are more inconvenient with the constant need to renew them) would tend to be exchanged into larger ones (or quietly return to the ground), so “dust” would not accumulate.