There are borders where science and philosophy are not able to go beyond.
Some people don't like to look at those borders, they find it difficult to see that they exist.
Other people see those borders more clearly, but start fantasizing about their meaning and what is beyond. I don't think that that is a proper way.
The borders have a tendency to move, at least our view of those borders.
Today I read about a philosophical and science border as described by Bernard d'Espagnat.
http://www.newscientist.com/article/dn16769-concept-of-hypercosmic-god-w...
"Unlike classical physics, d'Espagnat explained, quantum mechanics cannot describe the world as it really is, it can merely make predictions for the outcomes of our observations. If we want to believe, as Einstein did, that there is a reality independent of our observations, then this reality can either be knowable, unknowable or veiled. D'Espagnat subscribes to the third view. Through science, he says, we can glimpse some basic structures of the reality beneath the veil, but much of it remains an infinite, eternal mystery."
...
"There must exist, beyond mere appearances … a 'veiled reality' that science does not describe but only glimpses uncertainly. In turn, contrary to those who claim that matter is the only reality, the possibility that other means, including spirituality, may also provide a window on ultimate reality cannot be ruled out, even by cogent scientific arguments."
That proves to me that it might be possible that science will never go beyond certain borders. History told us that those borders will be changed, but it seems probably that the border itself always will exist.
That leaves us with the question how to handle in present days. What we know now is that we can't understand reality as it is. Not in quantum physics, and not in human behavior.
The current economic crisis exposes another border in science. Some people predicted a crisis like this would happen. But there have always been people predicting crises and big problems. Sometimes they are right, sometimes not. If millions of people make predictions randomly, then some of those prediction will turn out to be right. That does not imply that their method was right and will predict the future better then the methods of all those other people.
We can make economic models, but their also seem to be a veiled reality under our models of our economics. We just don't know what the future will bring. It is beyond our powers (yet) to go there in detail.
That also leaves us with the question how to handle in the present.
Both scientific borders make a case for the usage of the word pu.
Pu means: "everything I don't know or understand at this moment".
What is beyond the veil of quantum mechanics is pu (for me and probably for you and mankind as well). What will happen to the economy tomorrow is also pu.
If you use pu, it shows you what you don't know at this moment, and it makes more clear what you do know.
The word pu might show us what we really understand and what not. It helps us to understand some of the crises we face to day. The crises that are caused by the arrogance of our all-able-to-understand and all-able-to-control mindset. Let's look honest what we don't know and let's learn to deal with that. That is what "pu" is about.