I bought the much talked-about book Capital in the 21st Century by economist Thomas Piketty but have not yet cracked open its 700-odd pages. His basic thesis apparently is that when r>g, where r is the rate of return on capital and g is the rate of growth of economies, that leads to greater wealth and income inequality. His book looks at the data over a long period and suggests ways to reduce the inequality. Of course, his prescriptions will not be popular among the elites in the US who see the inequality as reflecting the fact that they are so much more valuable to society than the 99%.
He has given a 15-minute TED talk followed by five minutes of questions where he outlines the argument and the data that supports it.