为什么运动会要用金银铜三种金属作为奖牌的... ?

来自于古希腊诗人赫西奥德认为上古最美好的三个时代：
These metals designate the first three Ages of Man in Greek mythology: the Golden Age, when men lived among the gods, the Silver Age, where youth lasted a hundred years, and the Bronze Age, the era of heroes.
人类和神混居的黄金时代，青春不老的白银时代，英雄辈出的青铜时代 (有时英雄时代也可泛指所有这三个时代)
The custom of awarding the sequence of gold, silver, and bronze medals for the first three highest achievers dates from at least the 19th century, with the National Association of Amateur Athletes in the United States awarding such medals as early as 1884.
正式把这个序列用于颁奖来自于19世纪的美国业余运动员联合会，1884年他们首次按这个顺序给运动员颁奖。
This standard was adopted for Olympic competition at the 1904 Summer Olympics. At the 1896 event, silver was awarded to winners and bronze to runners-up, while at 1900 other prizes were given, not medals.
奥运会开始的时候奖牌也不是这个顺序，冠军拿银牌，亚军拿铜的，后来还给过别的玩意，到1904年才确定下来按现在金银铜的路数。1904年国际奥委会确立这个颁奖方式后后前两届的奖牌进行了追授。
参考wiki。