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Comment by avidiax | Hacker News Reader

People walk around with a loaded gun in their pants. They just (usually) carefully manage not to pull the trigger.

Would it be better to walk down the hall twice? Slightly, sure. Turns out it wouldn't have made a difference that we know of.

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Guns don't tend to go off just by the mere presence of another unexpected gun nearby, though.

They do tend to go off if people finger the trigger though.

Somehow I think it’s more likely people will fiddle with their loaded gun than with two halves of a nuclear bomb.

> I’d put this half in a pocket on this side and this half in a pocket on this side and walk down the hall.

I'm inclined to see that as uncomfortably close to fingering the trigger.

With one half in the pocket and the other in hand (while it's being placed into the "safe" other pocket) nothing prevents the latter from going unintendedly close the first.

Yep. Or you trip and fall, they spill out of your pockets, and someone helpfully fetches them for you.

What if two people walk down the hall doing the same thing in different directions? ... Oh I forgot my slide rule ... !#FLASH#! ... what was that!? Oh shit.

Half joking. Is the material and spatial separation of a lab coat enough to prevent a reaction between two lumps of plutonium of sufficient combined critical mass? It might be since it's so bad at penetrating anything solid, but I don't know.

Considering the original demon cores were held apart by a screw driver, the answer is technically yes.

It's still a horrifyingly unsafe thing to do.

https://en.wikipedia.org/wiki/Demon_core#/media/File:Ticklin...

The Hollywood version of events: https://www.youtube.com/watch?v=AQ0P7R9CfCY

Further reading:

https://www.science.org/content/article/near-disaster-federa...

Technically, it was the neutron reflecting sphere was was held apart by a screwdriver.

Remember the demon core thing happened more than once, too.

Good thinking.

One of the things modern "computing practices" taught us is the myriad of ways things can go wrong, they were probably a bit more naive at that time

It's Murphy's law squared

> It might be since it's so bad at penetrating anything solid

This isn't the case!

Plutonium 239 is relatively safe, merely an alpha emitter which is what you're talking about. But that isn't where the danger comes from. The danger comes from the Plutonium 240, which is present as a contaminant in all plutonium weapons cores. Plutonium 240 spontaneously undergoes fission, releasing neutron radiation which is very penetrating. If you bring two halves of a core together, neutrons from the spontaneous fusion of Pu-240 can cause a chain reaction; this is the reason gun-type bombs don't work with Plutonium cores; they give off too much neutron radiation and would react prematurely if you tried to build a Plutonium bomb like that.

Ah, so purely a matter of separation in the case of a lab coat.

> Is the material and spatial separation of a lab coat enough to prevent a reaction between two lumps of plutonium of sufficient combined critical mass?

Inverse-square law [0][1] applies...

[0] https://en.wikipedia.org/wiki/Inverse-square_law

[1] https://energyeducation.ca/encyclopedia/Inverse_square_law

This would be something out of an Gary Larson comic.

What if he trips over something? It's unnecessarily risky, just like the guy who killed himself while showing off separating cores with a screwdriver.

Imagine this person bumping into anther such idiot with pockets full of plutonium.

I pictured them leaving work and going to play billiards with it still in their pockets.

(Just letting my mind wander - I realise using plutonium as a cue ball is very unlikely)

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