Hi, first time posting here. I was watching a show about hydrogen/helium balloons and it got me thinking about buoyancy in atmospheric gasses (nitrogen) and what might work better than the common gasses and I considered that since the goal of a balloon is to reduce the internal mass relative to the mass of the medium why not just eliminate it entirely and use a vacuum? I understand ordinary balloon material would not work as it would simply be crushed by atmospheric pressure... so my question to you guys is can you think of any way to maintain a volume of vacuum or near-vacuum while still keeping the object light enough to provide more lift than a traditional helium balloon? If someone loves doing math you could come up with the equation to relate the volume of the vacuum with the lift capacity it would have if it could be maintained in the atmosphere... Now, I've seen video of a train car (the cylindrical ones that carry liquids) being completely crushed by nothing but atmospheric pressure due to very low internal pressure, so I know this container would have to be fairly robust and we likely are lacking the material to make this feasible, but what about materials that are on the horizon, like something made with carbon nanotubes maybe? Maybe with a reinforced internal structure like a honeycomb structure with thousands of pockets of vacuum? It would be great if we could create something like this with significant lift capacity to deliver space vehicles high into the atmosphere where they would "launch" from the floating platform or something, since that would be reusable ad infinitum it would reduce the cost to deliver a payload to LEO by a great deal I would imagine.