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Comment by userbinator | Hacker News Reader

Bureau agents acknowledge that it is unlikely that even modern bomb squads and technology could make much headway disarming Big John's improvised explosive without setting it off.

Any (3D?) imaging technology that would allow seeing inside the upper box with enough resolution to determine the wiring?

Also:

The inside surfaces of the boxes were lined with rubber sheeting, which were in turn lined with conductive foil. If something metal such as a drill bit or saw blade penetrated the outer metal casing and the rubber sheeting, it would close a circuit between the metal housing and the foil.

How about cutting tools made of non-conductive materials?

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Scrap from the foil and the metal housing is also conductive.

The best bet might have been to freeze the battery so it couldn't set off the blasting caps. Possibly by pouring liquid nitrogen into the top box through the panel with the switches.

Would liquid nitrogen trigger the float switch?

If you got enough liquid in there, yes, but I think it's really unlikely you'd get that far. Until you've cooled things down, the liquid you put in is going to boil off, which has a corresponding volume expansion of almost three orders of magnitude. Without good ventilation (which you're not going to get if you're not cutting into the box because of the contact switches) this is going to lead to an explosive pressure buildup in the box, which seems like a really bad idea under the circumstances. There are lots of other possible ways for it to go wrong, e.g. the wires could break under thermal stress, which might lead to bad things; the boiloff could disturb the pendulum in the tilt sensor; etc.

Yeah, and there was allegedly a pressure sensor in there too, which could trip it when the gas expands. Tricky.

Maybe they could have tried to deplete the battery somehow? This is all academic of course.

> Any (3D?) imaging technology that would allow seeing inside the upper box with enough resolution to determine the wiring?

Sure, which one? This is not CSI

They were X-raying it already, so if they did it from enough angles they would probably be able to do something like this:

https://en.wikipedia.org/wiki/Industrial_computed_tomography...

Should have included visible light/IR sensors inside the control box. Second-line defense against opening the box, first-line defense against x-raying the box.

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