In March you could buy a Bitcoin, one of a number of ‘cryptocurrencies’, for about US$1,200. Since then its value has increased more than tenfold to over US$15,000. So why the excitement? Is it yet another irrational speculative bubble driven by what John Maynard Keynes used to call ‘animal spirits’? Or is the excitement really about the de-centralised technology that underpins Bitcoin? Some argue that this technology, known as blockchain, is as revolutionary as the internet and will change how we bank, work, and live. On Newshour Extra this week, Owen Bennett Jones and his guest discuss whether Bitcoin and blockchain are leading us to a brave new world or towards another financial crash.