[edynoid]

Don't know about the material science behind it. But from a purely physical point of view, the problem there is that void (= vacuum) does not have any pressure. So the frame would have to support itself against the atmospheric pressure instead of the gas doing it from the inside – that is a big technical challenge. The catastrophic failure scenario (hull breach) would be an implosive compression of the entire hull, which kinda sounds worse than a hydrogen-fuelled fire.

[haylel]

I read about this a lot a while ago, the main solution I came across was that in the diamond age when we get to that point in societal development. We'll be able to make tiny diamond bubbles with a vacuum inside, and they can be used to create airships and floating platforms. The airship doesn't have to be a single large vacuum diamond hull, but could also be made from many smaller diamonds which would help prevent a catastrophic failure. The diamond bubbles would be strong and light enough to hold the vacuum.

[beautifulfreak]

The wikipedia entry on "vacuum airships, as they're called," is nicely detailed. https://en.wikipedia.org/wiki/Vacuum_airship

[gibspaulding]

If I remember correctly, one of Edgar Rice Burroughs' Pelucidar books involves a vacuum airship as well. His was just made of some sort of future super strong unobtainium type matterial though.

[roenxi]

If luck was kind there might be a sweet spot making it possible to make a small lighter-than-air vaccume hull, and then add a lot of those to a craft. Something suspiciously like attaching a large number of balloons to a frame. Maybe some wonder material; carbon seems to do everything according to the headlines.

That'd solve the implosion problem since presumably all the little hulls wouldn't fail at once.