Kiyotaki said:
How come we use currency, what if everything was free and done by charity workers?
aye you have been watching too much zeitgeist. Contrary to what zeitgeist or that one episode of south park suggested, our species does not and will not do well with communism, we do not have a hive structure mind archtype, controlled by a universally accepted ruler, were we can all work together to achieve a common goal, we, pre agriculture, were in free relatively law less bands, leisure was our way, working only 2 hours a day (approximately) to catch food (most of the time). Its in our nature with out incentive to be lazy.
Also we would not experience "grand scientific advancement" as zeitgeist suggests, in fact just the opposite, all due to incentive and resources available, by restricting resources and making money a resource, we are forced to find ways to cut down on resource consumption, and find new ways to efficientise, and make things cheaper, easier to produce and far less waste full to save money. DUE to scarcity we have to innovate!
Science benefits from capitalism (as long as its not free market capitalism (the other side of the spectrum the "far Right") due to governments being able to support scientific projects that benefits the country, and often, the world (see NASA, and inevitably chinas space program too)