[saltyfamiliar]

Sure, but if you want it to be _sound_ money, it has to backed by some kind of inherent scarcity or guarantee which implies work and energy expenditure. If you want to be able to store it on a flash drive and transfer it to a different continent with no intermediaries, that too will cost something. If it were 'fictional' enough to be free, it wouldn't be useful.

[dTal]

I don't think that's inherently true. What's required is trust that one hasn't fiddled the numbers, and scarcity of some token is just one way of accomplishing that. Here's a monetary system, not unlike bitcoin:

All transactions occur in the market square, at the Town Ledger. Everyone's balance is public, and every transaction is witnessed by everyone else lining up for their turn at the Ledger. Everyone keeps an eye on their balance and the balance of a few friends. The mayor locks up the Ledger at night of course, but discrepancies tend to get the mayor lynched so she keeps a very close eye on it.

The system started by tracking barters, but it got too confusing to track all the different things, so it was agreed to simply write down a number equivalent to the trade's value in chickens as determined by average exchange rate over all previous transactions - nothing special about chickens, they were just a very commonly traded good which made for well-defined exchange rates.

After a few chicken runs, the villagers agreed to abandon the chicken standard in favor of shiny meteorites that fell from the sky once every ten years. They were technically slightly inflationary, but people lost them from time to time as well so it kind of evened out. Anyway, there weren't many of them around; most transactions were in fractions of a shiny meteor-pebble. It was just a convenient reference.

And nobody had to mine anything.