The quality debate about scientific merit aside, if the U.S. wants to remain "the best", then we need to incentivize the best scientists and researchers in other countries to come here and become U.S. citizens. A lot of famous physicists, mathematicians, and logicians have done this over the past 100 years. Unfortunately, the attractiveness of becoming a U.S. citizen is waning because (1) current U.S. policies on sci…
Also, here is a Wikipedia link to what GDP PPP (Gross Domestic Product Purchasing Power Parity) actually is [2]
[1] http://www.wolframalpha.com/input/?i=US,+China+GDP+PPP [2] https://simple.wikipedia.org/wiki/Purchasing_Power_Parity