Reason: The total amount of gold is limited, and the dollar (in theory) is infinite (the Fed can print money or tighten money to reduce the circulation of dollars).
The reason for the rise and fall of the dollar is determined by the supply and demand of the dollar. Assume that the total amount of gold in the market is 10000g, and each gram is 1 USD, corresponding to10000 Yuan, which belongs to a balanced market, and the dollar and gold are11. At this time, the circulation of dollars has doubled. There are 20,000 dollars in the market, but gold is still only 10000 grams. In order to maintain the balance of 11,the price of gold will double, that is, 2 US dollars * 10000 grams of gold /20000 US dollars, and gold and US dollars are1.