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Comment by Kranar | Hacker News Reader

Definitely don't think that's true. Yes, Edward Teller did propose a design for a 10 gigaton device but the initial devices based on that design ended up being a dud, not working as intended and the project was abandoned in favor of more practical nuclear weapons. Maybe in theory such a device would be possible, but even at 10 gigatons it wouldn't come remotely close to cracking much of anything.

The largest confirmed explosion on earth was on the order of 1 teraton (1,000,000 megatons) caused by the Vredefort asteroid impact and that certainly left a crater but did not come close to cracking the planet forever. It left a crater 40km deep and 300km wide, which is absolutely enormous and mind boggling and if it happened today would certainly cause a mass extinction event, but the Earth would recover.

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>would certainly cause a mass extinction event

That's a bit bigger than Chicxulub. Someone estimated the heat from the re-entry of debris at 20kw/m2 for 7+ minutes, not close up, but far away. A random study on firefighting I just skimmed said that heat flux will destroy clothing in about 20 seconds and produce 3rd degree burns in another 20 or so. So, uh...ten times 40 seconds over practically the whole world would probably not be good.

The collision that produced the Moon is speculated to have left the surface of the Earth approximately as bright as the Sun for a while, so it could be worse, but there's hardly any difference for the forms of life we can relate to.

Anerobic organisms deep in the crust would have an easier time of it.

> but the Earth would recover.

The earth recovered its collision with the asteroid that eventually gave us the moon, yet the earth has actually been “taken apart forever” (since a significant fraction of its former mass now belongs to the moon).

I can’t find exactly what they said, but a weapon that size is the easiest to deliver because you just bury it in your own backyard. It’s so destructive it doesn’t matter if it explodes on your enemy or you.

So it's impossible to design such planetcracker weapons, even in principle? Since the possibility of such design is all I claim.

How big is big enough? There is no physical, engineering, or practical limit to how much worldly damage can be done with supers. The yields increase exponentially with linear increases in effort (stages / size).

The point isn't the exact number, it's the fact that it's so reasonable to attain no matter the number.

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