英语句子结构,We need to recognize that the trickle-down promise of

英语句子结构,
We need to recognize that the trickle-down promise of conservative theorists has turned into a gravity-defying reality in which wealth has flowed upward disproportionately and,too often,undeservedly.
in which wealth has flowed upward disproportionately and,too often,undeservedly.修饰什么,为什么用in which?

in which
可以翻译成在„„里面
in which是介词加关系代词,引导定语从句