The americans eat the chickens, the chinese eat the feet. For some reason, the chinese have yet to develop a chicken with more than two feet, and the americans have yet to develop a taste for chicken feet.
The dollar is constantly going up and down against world currencies- if you look at the dollar versus euro for the last ten years, while the general trend has been for the dollar to fall against the euro, there have been some big peaks and valleys along the way.
In the last 5 years, its been as low as $1.20 and as high as $1.60 per euro- thats a 40 cent range, and all due to a wide variety of circumstances that Bernanke only wishes he could control.
http://www.oanda.com/currency/historical-rates/
It has not been, and probably will not be, a simple predictable single line downward- it jumps all over the place.
The chinese have been doing a better job of keeping the yuan relatively stable against the dollar, but only because they routinely will dump $20 or $50 Billion into the market, buying and selling to support their state determined exchange rate. The USA does not have this luxury, being a net deficit economy, not a net surplus like the chinese.
Currently, the US is a pretty small portion of the chinese economy- exports in general are somewhere around 20% of the chinese economy, and, of that, the USA is only about 20% of chinese exports.
So, in total, the US exports only represent about 5% or so of the chinese economy.
The US needs them a whole lot more than the Chinese needs the US market.
Especially since the crash has weaned a lot of chinese industries of US customers- thousands of factories that made things like toys and christmas decorations closed in the last 3 years- and the chinese economy still is growing at over 10% a year- so all those jobs have been absorbed making things for china, and for export to their other customers.
The US is becoming less and less relevant to the chinese.
The dollar is a safe international currency- and when we see events like the recent unrest in Libya, that is reinforced- in the last couple of weeks, the interest rate the USA must pay to borrow money has gone DOWN- because the "invisible hand" of the world market finds the USA to be an even safer place to invest in troubled times.
Interest rates on T Bills are a direct result of consumer confidence- Norwegian pension funds, Chinese banks, Saudi Princes, Japanese grandmas- all buy T Bills and US bonds, and all are buying MORE of them, and thus lowering the rates, when trouble stirs around the world.
This is not a theory or my ideology- its a simple observation of real world events.