/sci/ - Science & Math

>>10242635
Go ahead, provide schematics for a system that can survive, economically send material back and work over the entire range of pressures you require. It sounds easy when you put it like that but the actual engineering required is not.
>>10242631
>balloon life jackets
No, its dense but it's not that dense. We're talking about significantly different scales here and cities are mostly empty space. Even if your balloon was somehow a vacuum (optimum lifting), you'd need to get it to expand to ~50 m3 and quick enough to matter. A helium tank large enough to do that would be huge - even if helium was magically weightless and you discarded the tanks as you emptied them, you'd need more than 5.5 of pic related (1.5m tall, 0.23m dia and each weighing 60kg). Not exactly something you could carry around.