Hi, I'm not a physicist or anything so my question here can be silly, please take it easy on me and tell me -if so- why wouldn't this work. My thought is as follows: We need a pipe, water, a vacuum vessel that can expand and contract by mechanical means, copper wires, and a magnet. First hold the pipe vertically and fill it with water, put the copper wires around the pipe in coils. Attach the magnet to the vacuum vessel, and put it in the pipe. Now, from basic physics, if the vaccum vessel has less density than the water it will flow, and if it has a higher one it will drown. Assuming when it's fully contracted it has higher density than water, it will drown and the magnet will move throgh the coil and produce current. Once it hits the bottom, the vessel expands, hence the density is lowered -greater volume means less density, right?-. Again assuming it has less density than water when it's fully contracted, then it will flow up and the magnet will move throgh the coil and produce current again. And it expandes again when it reaches the top, repeating the whole mechanism again. The longer the pipe the more electricity generated -since we have more wires cutting the magnetic field-, and at a certain length, this set is "supposed" to produce energy more than it consumes to expand and contract the vessel. I know, it might not be financially feasable, but I'm talking about the concept. And again, I'm not a physicist, so I may have made a completely silly mistake here. Your thoghts please.