By measuring how long that pulse takes to return, it can place the distance to the point of reflection to within that level of accuracy enough to tell whether an aircraft's wing-flaps are up or down.
But it has shaved nearly a full percentage point off its estimate of growth next year a reflection that after the spurt of growth in the first quarter of this year, the economy has been weaker than expected.
The basic point that he would make was that the decline of unions wasn't a reflection of consumer choice, in the way that hot movies and popular toys are said to be.