Suppose we have a resvoir full of water and a dam at one end ten meters high, We attach to the bottom of the dam a rubber pipe lets say 3 million kilometers long,we take the plug out of the end of the pipe and the pipe fills with water and eventualy water flows out of the pipe.Next we take the open end of the pipe and we lift it to a height of 15 meters, information about the change in pressure which should stop the flow of water travels back down the pipe at the speed of sound in water, taking a few days. So the question is whats going on does water continue to flow out of the open end of the pipe while conditions say that the water flow should stop,how does water entering the pipe at the dam end know that the flow at the other end should have stopped ?
Does the water continue to flow thereby violating the conservation of energy, or does the water flow stop suggesting that the information traveled faster than the speed of sound in water down the pipe?

Or we have a tap on the end of the pipe, we close the tap water is virtualy incompresable, a shock wave travels back along the pipe at the speed of sound, water is still entering the pipe because it doesnt know that the tap is closed.