I've been wondering a couple things: 1. How much energy would it take to evacuate* a 1 cubic meter volume at sea level and some convenient temperature? 2. If the structure containing the vacuum weighed, say, 1kg, how high up would it go? *arbitrarily close to a vacuum to avoid getting into quantum mechanical issues Using ideal assumptions is fine with me (e.g. no temperature gradients caused by heating from the ground, no wind, etc). As far as I can tell, the answer to the first question would be about 100 kilojoules. I came up with that by assuming the volume was like an accordion 1m^2, and had to be stretched to a length of 1m from an initial length of 0. Since the motion is resisted by the 100 kilopascal atmospheric pressure, and the distance is 1 meter, I get 100 kilojoules. I don't know what the answer to #2 is, but I would expect the answer to be less than 10km. I'll probably have follow-up questions after getting answers to these two.