Isn't this where multi currency systems come into play? Bimetalism, multimetalism?
I'd guess multiple systems as an exchange for each of the worlds current currencies would be able to establish a true exchange rate based on how bitcoins are being bought and spent between currencies. The results of that could be very scary and I'm not sure there would be enough bitcoins (or bank reserves) to support it once the arbitrage starts.
Not sure? No problem... cue empiricism!
Consider for example a few nations such as the Canucks, the Brits, the Martians, each with their own blockchain (CDN, UKB, MBC). Add a couple of major multigalactic corporations such as General Mining Corp and General Retirement Funds, also with their own blockchains (GMC and GRF). Maybe a multinational metanation would be useful too, like the (galactic/multi-galactic) United Nations with its own blockchain scrip (UNS).
We know what assets each of these entities owns, so if we know how many coins to divide its assets among we know how much of its assets each coin represents.
Naturally the Canucks like to denominate loans they make to others in CDN, so when a miner who is paying 1%/day to GMC on startup loans comes to the Canucks looking for refinancing at a lower interest rate they would like repayment to be in CDN. But there are a lot of mining corps out there, so a bunch of entrepeneurial developers, who, of course, favour devcoin (DVC), forms a new multigalactic corp, General Financial Corp to do the legwork of finding cheaper interest rates for busy intergalactic miners who are busy enough running their vast mining operations that they really don't have time to go hobnob with politicians, clans, governments and so on trying to suck up to one enough to talk them into giving a better interest rate loan to refinance those usurious startup loans the GMC and GRF corps gave to mining startups.
The GFC denominates its loans in devcoins, and that turns out to get them into a nasty situation, because no one knows exactly what assets the sum total of all devcoins actually represents, so markets instead of actual inventories of assets end up getting in on the devcoin valuation estimates everyone is trying to use.
General Financial Corp borrows a million GRF from the Canucks, but of course how much they owe is denominated in CDN, not in GRF. The conversion rate of CDN to GRF was looked up when they took the loan, to record how much CDN they owe the Canucks.
The usual situation for a mining startup was to get half their financing from GMC and half from GRF, so General Financial Corp converts some of its borrowed GRF wealth into GMC currency so they can offer to miners to refinance both their loans at once, getting them off the 1%/day (Earth day, not game day; one earth day is several game days) hook, offering them half a percent a day. (They did their bulk borrow from the Canucks at a quarter of a percent a day.)
Take a look at a table of asset values expressed in CDN at
http://galaxies.mygamesonline.org/digitalisassets.htmlTake a look also at the share values tables, wherein sGFC is the shares of the General Financial Corp.
Devcoin's value is very volatile because one never knows what the sum total assets of all devcoins in the aggregate add up to so one ends up doing fudging estimations like "I wonder how much bitcoin it would buy today on such and such a planet in such and such a galaxy", or "I wonder how many tons of deuterium it would buy in such and such a galaxy" instead of being able to figure aha there are this many coins each being in essence a share of a mutual fund that owns this list of assets, many of which have well known relatively nonvolatile values...
An important thing to notice in all this is the total number of devcoins owed to GFC is vastly, by orders of magnitude, larger than the total number of devcoins that will be minted in the next gosh knows how many years. These folks do not go to market to buy and sell things, they look at their conversion rates table. If the total assets of the Martians are five times the total assets of the Canadians then one Martian coin is worth five Canadian coins, if both happen to be (as they are) chains of 21 million coins each (or, in general, of the same number of coins each).
So when a miner wants to pay some of the devcoins he owes, he tells the folk he sells the stuff he mines to to please remit the payment to the General Financial Corp to be credited against the loan. Usually people buying mined stuff pay in GMC or GRF. The financial corp looks up the current conversion rate of GMC or GRF to devcoins, and credits against the loan accordingly.
Basically there is a difference between units of account and actual "specie" aka "coins". ("Cash"?) The quantities on the books of how much of what is owed to who is not limited to the number of "actually minted objects" to which the units of account refer.
I suspect it is not by sheer coincidence that the forex market is much larger than other markets; quite possibly it needs to be absolutely vast in order that mere material products being shipped around from owner to owner hardly makes a dent in the "ballast" of "units of account" that maybe somewhat help against volatility. (I keep wondering if financial "ballast" is in any way akin to the "ballast" of coils and/or capacitors used in some electrical applications...)
-MarkM-