which will be the economically strongest nation in the world after 30 years?  

india i believe.. it is already the 3rd largest in the world in PPP terms...

its hard to predict, sometimes figures dont work at all!

for country even without a good sewage system like cities in india, how could it be the no 1 in 30 years?
the same factor applies to china.

so the strongest still could be us, russia, china, japan, germany, india.

Ethics should be like Gilles Deleuze write: " big messy thoughts, with no concrete conclusions."She only have to learn to deal it in the future and that tinny things can be on our mind for long long years or forever.
The ethical question there is that she shouldnt steal whatever thing it is. She had to wait to have money or go to a library or try the work on the library till the owner offer her a copy.
If i was her, i wouldnt buy or steal that book. It would be loss of time read Marx.
We just learn how to be bitter with him. To learn something about society, politics and economy should read John Keynes