Finance, it seems, is more complicated than physics. That may explain the popularity of metaphors borrowed from astronomy in financial discourse.

Take “dark matter”, last year’s buzzword to explain why the US has not seen a sharp deterioration in net investment income, in spite of persistently high current account deficits. The reason, dark matter proponents argued, lay in invisible US exports. Giving full credit for items such as the knowledge embedded in overseas subsidiaries of US companies would suggest a much rosier picture.