OK, we can all see it: bitcoin looks a lot like a bubble. It stinks of irrational exuberance: it is incredibly volatile, and not only does its price continue to increase, but it is doing so at ever accelerating rates.

It took 1789 days for bitcoin to go from nothing to $US1000. Then 1271 days to get from $US1000 to $US2000, and just 13 days to jump from $US6000 to $US7000, its latest milestone.

Individuals are selling their houses and giving up their life savings to put everything into bitcoin, seemingly more out of speculation that its price will continue to rise than because of any serious belief in its intrinsic value.

Many of the characteristics of a classic bubble - the fact that everybody is talking about it, extreme predictions about its future price, and the parabolic price curve - appear to apply to bitcoin.