If a vehicle could continuously cool the air in front of it and heat the air behind it, the air in front should contract and the air behind expand, reducing the pressure in front of the vehilce and increasing it behind the vehicle. This should pull the vehicle into the cooler air at the front, and push the vehicle away from the hot air at the back, propelling the vehicle through the atmosphere without moving parts or any additional propulsion. (Let's assume for the moment a helium balloon type object, that just floats at a certain height, for simplicity). Another way: if a similar blimp-like vehicle could somehow draw air over its surface from front to back, using some inherent powered attributes of the (obviously special) surface, it should also be pulled through the air without any additional propulsion. It seems to me that these mechanisms might tend to overcome wind resistance, by using the propulsive energy (that might otherwise be used to drive say a front propellor) to directly move the air over the surface of the vehicle instead, applying the propulsive force at the very point where resistance develops, in an attempt to overcome or eliminate it. For example, let's say for example, that a film of oil could be moved over the surface continuously from front to back by some applied energy, then returned to the front of the device by being pumped through a tube from back to front. Or perhaps moving belts could more or less cover the surface of the vehicle (all travelling backwards, and somehow return in a loop to the front internally. Any friction between the external air and the oil or belts would tend to flow the air backwards and thus draw the vehicle forwards, apparently with reduced air drag over a more conventional method of propulsion. Any comments, thoughts, etc on whether the same amount of energy applied in this manner would result in much reduced frictional air drag or not? Since air drag is proportional to v squared for macroscopic objects at normal speeds, it maybe could save large amounts of energy if we could overcome this problem. Alternatively, we might be able to go faster for the same energy consumption :) This would apply to cars, planes, etc, not just blimps.