Once you start moving along such a curve, you are required to come back to precisely the point at which you started. (discovermagazine.com)
An observer standing outside, however, has what is seemingly the opposite problem: What happens along such a curve can not be uniquely predicted from the prior state of the universe. (discovermagazine.com)
Almost all recessions have been preceded by an inverted curve (with short term rates higher than long term), and such a curve usually points to lower rates in the future. (mortgage-x.com)