# Tiny spheres of vacuum **URL:** \ **Category:** Factual Questions\ **Created:** [June 27, 2025, 4:38am UTC](https://boards.straightdope.com/t/tiny-spheres-of-vacuum/1020185 "2025-06-27T04:38:37Z")\ **Posts on this page:** 1\ **Showing post:** 9
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [June 27, 2025, 11:18am UTC](https://boards.straightdope.com/t/tiny-spheres-of-vacuum/1020185/9 "2025-06-27T11:18:01Z")
@Mangetout utterly nailed it in the first post and more succinctly here in the second. Those prior threads he cites go into great detail. Worth reading. There are others I think. Vacuum is only slightly lighter than hydrogen. But hydrogen at ambient pressure of your outside atmosphere at whatever altitude you want to cruise is incredibly powerful at supporting your sphere from the inside. Conversely vacuum provides zero support. You can make your hydrogen spheres out of the thinnest lightest imaginable plastic sheet, _if_ they’re filled with hydrogen (or any gas really) to the same pressure as outside. But if it’s vacuum inside and atmosphere outside, you need very stiff, relatively thick walls to keep the sphere from being crushed. The extra lightness of the vacuum doesn’t come close to repaying the extra heaviness of the container. It’s a losing game all the way around. More cites: > [@Have we been able to construct vacuum buoyant structures yet?](https://boards.straightdope.com/t/have-we-been-able-to-construct-vacuum-buoyant-structures-yet/787114): > > If you build a structure that is simultaneously light enough and rigid enough to stand up to atmospheric pressure, you could suck out all the air and make it float. Have we developed the engineering prowess to make something like this yet? If not, how close are we and what are major engineering constraints that still limit us? > [@Vacuum balloon ?](https://boards.straightdope.com/t/vacuum-balloon/241462): > > I have a feeling this is an obviously dumb question, but here goes anyway. A hypothetical experiment is set forth below. First obtain a very lightweight yet very strong carbon fiber sphere, such that it resembles a large tough plastic balloon. Said sphere, is about, one meter in diameter and hermetically sealed except for one small valve. Said shut-off valve is used for the following two experiments: A: The sphere is filled up with helium gas; the valve is then shut, whereupon the sphere acts… --- _[View the full topic](https://boards.straightdope.com/t/tiny-spheres-of-vacuum/1020185)._