Just occasionally a big idea makes waves across the world. HARDtalk speaks to French economist Thomas Piketty whose book, 'Capital in the 21st Century' has become an unlikely international bestseller. His thesis carries echoes of Karl Marx - modern capitalism, he believes, works in favour of entrenched wealth and exacerbates inequality. His research and conclusions have come under intense fire; has Thomas Piketty emerged unscathed? Show less