Russian scientists (I think) managed to turn lead into gold accidentally, their nuclear reactors (or something like that) bombarded their lead containers with so much radiation that the lead lost two protons (Or around that, I don't exactly have a copy of the periodic table with me), and tuned it to gold.
Of course, the gold was un-usable due to the massive radiation it possessed, but hey, who needs a long life when you can spend your last few hours spreading your fatal radioactive genes onto the many women you'll buy with that nice, hard gold?
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That aside, I think we'd go to something like a favor or a trade and barter system. Or perhaps we would pay people in commodities, which are the only reasons we really get money in the first place after all.
Now, I would have to wonder how workers at corporations would be paid though, it's one thing to wonder about buying something, it's another to wonder how an office worker would get paid for working overtime, or something of the like.
For commodities to work, a really strict government would be needed, and theft would probably be a huge problem.
Trade and barter is just too disorganized, wouldn't work well at all.
And favors wouldn't work for corporations, not even close, would only work in a very small society.
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That being said, I don't think we'll lose money, we have a good thing going with paper currency. It obviously has no inherent value, but it lets us decide how we'll buy other things. Gold may lose value, everything may lose value, but cash and the concept of it lets you decide what you want in life by giving you the freedom to procure anything if you have enough money. It works.