this post was submitted on 02 Dec 2023
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[–] Hedgehog@lemmy.blahaj.zone 61 points 11 months ago* (last edited 11 months ago) (2 children)

Turns out it'd be a dissapointingly small sphere:

US annual defence budget = $800 billion

2% = $16 billion

Obsidian cost per kg = $5

Total kg in budget = 3.2 billion kg

Density of obsidian = 2.6 g/cm3 = 2600 kg/m3

Total volume of sphere = 3.2b/2600 = 1230769 m3

Volume of sphere = 4/3 π r^3

Radius = (3V/4π)^(1/3) = 66.48 m

The sphere would only stand at 133m tall, I propose we instead utilise the entire defence budget for a much more skyscraper like 490m tall orb

[–] lseif@sopuli.xyz 41 points 11 months ago

ignores engineering and construction cost. but we can assume that all people involved would work for free, because its a massive honour

[–] pokemaster787@ani.social 29 points 11 months ago

Well that's assuming it's completely solid and not hollow. Hollow would probably be pretty huge, although the structural rigidity might not be great. Maybe we make a giant obsidian 3D printer and print it at like 10-15% infill.