Recent content by Rayner

Would it be possible to use diffraction to focus the energy of sea waves, on the principle of the zone plate (https://en.wikipedia.org/wiki/Zone_plate) but reduced to 2 dimensions? This could be done by an array of wave-opaque objects such as floating breakwaters, particularly along coasts...

Many thanks Jeff and Fred I had previously assumed that the power to pump air to a diver, even in shallow water, would be far beyond what the diver could provide using his or her own muscle power alone. But I thought that if one could somehow part-use the energy in the exhaled air to help...

Would be grateful for a formula for the power required (theoretically) to move air down to a specified depth underwater. Metric if possible please. My calculations seem an order of magnitude too low.