You are right, money is not a recipt for gold anymore. It is just a bit of paper you must accept by law as a form of payment from someone.
When one country trades with another country, they dont send any gold or money between countrys, they just write up IOU's. in effect you are exporting to one country, expecting them to export back to you for payment, and the money is just the Tally on who owes who.
But you still need an agreed money to trade between countrys, the world use's the American dollar, so when you buy good from China Australia buys american dollars with its Australian dollars, then use's those American dollars to buy from china, and visa versa.
This is like what europe does with the euro.
The problem is, take america in trillions of debt, it can print its own money and still buy stuff because we all use american dollars.. when you start printing money, your money becomes worth less. which is a problem because other countrys (like china) who hold american debt dollars has those dollars devalued on them.. so america can make its debts cheaper.
The problem with this is no one then wants to hold those dollars as its being devalued on them.. so America then upts its interest rate to pay intrest on the dollars it owes people (in export value). But in the present case at the moment its sitting on 0% which is why china and russia and other countrys want to ditch the USD as world currancy.
So with Europe, if greece detaults and they wipe out all the money as gone.. they are effectivly printing money, devaluing their currancy.. this means the value of the currencie drops, and the interest rate needs to go up to give it more value.
This makes it harder for the people as import costs go up, and borrowing costs go up.
