I dreamt that I was involved in some sort of engineering project dedicated to energy conservation. It involved miles upon miles of plastic pipes. White in color, their walls were quite thin and soft, making them look like long, tubular balloons. The pressure in the pipes was vital for the operation of the entire system. For some reason that escapes me now, the pressure was to be regulated by tying the pipes into knots. One of my tasks was to find out by how much the pressure would be affected by each knot. I remember figuring out that a knot would decrease the volume of a pipe by the volume of a sphere the diameter of the pipe itself. In fact, I visualized two hemispheres touching at each knot. I was rather proud of this discovery, too. Only when I woke up it dawned on me that knots would block the pipes entirely, thus making the pressure in them perfectly irrelevant.