Submitter, you cannot discuss a currency's half-life without discussing inflation. In fact, a currency's half-life is nothing more than a fancy arbitrary value

Submitter, you cannot discuss a currency's half-life without discussing inflation. In fact, a currency's half-life is nothing more than a fancy arbitrary value determined from inflation: the time it takes for a currency to lower it's value by 50%. Also, economists do discuss it, specially within the scope of hyperinflation, but it so happens to not add much value to the discussion, if any at all.