potassium-40

An idea circulating online proposes defining a currency in terms of something that cannot be hoarded: a radioisotope. Under the scheme, anyone holding a stock of potassium-40 would have to keep spending effort enriching natural potassium to maintain their holdings, and accumulating too much would become physically unsafe. The proposal is framed as an alternative to gold or bitcoin-style assets that reward hoarding, though it appears to be a thought experiment rather than a serious plan.